EMBRYOLOGY AND FETAL DEVELOPMENT
EMBRYOLOGY AND FETAL DEVELOPMENT
A) Oogenesis
Oogenesis is the process in which the development of mature ovum (female reproductive cell) takes place.
Oogenesis is a process that starts during the development of the embryo itself.
Primordial germ cells develop when an embryo develops in a pregnant woman.
In female gonads, germ cells undergo a rapid mitotic division (a type of division in which two daughter cells with the same number and type of chromosomes are produced by the division of the parent cell) and then convert into oogonia.
The majority of these oogonia divide continuously, some of which enter the prophase of the first meiotic division called primary oocytes. They are covered by flat cells called primordial follicles that are present in the cortex of the ovary.
At birth, there are no meiotic divisions and all oogonia that have completed the prophase of the first meiotic division are replaced by primary oocytes that remain in the resting stage (dictyotene stage), a stage between prophase and metaphase.
The total number of primary oocytes at birth is estimated to be approximately 2 million.
Primary oocytes do not complete the first meiotic division until puberty. At puberty, about 40,000 primary oocytes are left behind, the rest being atretic. About 400 of these ovulate during the entire reproductive period.
Then, maturation of oocytes takes place. Now, the number of chromosomes is reduced to half.
Before the start of the first meiotic division, the primary oocyte doubles its DNA by replication, so they have double the amount of normal protein content.
It consists of 22 pairs of autosomes that determine body characteristics and one pair of sex chromosomes such as XX.
The first stage of maturation occurs with full maturation of the ovarian follicles before ovulation. And final maturation takes place only after fertilization.
Then, the primary oocyte undergoes the first meiotic division that gives rise to the secondary oocyte and a polar body. Both are of unequal size. The secondary oocyte has a haploid number of chromosomes (23, X) but almost all cytoplasm and the polar body also contains half the chromosomes (23, X) but with less cytoplasm.
Ovulation occurs immediately after secondary oocyte formation.
The secondary oocyte completes the second meiotic division (homotypical) only after fertilization by sperms in the fallopian tube.
It results in two unequal cells each containing 23 chromosomes (23 X) with a large one called the mature ovum and a smaller one called the second polar body.
In the absence of fertilization, secondary oocytes do not complete the second meiotic division and degenerate.
•> Chart Presentation of Oogenesis
Oogenesis
↓
Germ cells
↓Mitosis
Oogonia
(Oogonia)
↓
Primary Oocytes( 46 , XX)
↓
Arrested first meiotic division (up to puberty)
↓
Maturation of Graafian follicle
↓
Completion of first meiotic division
↓
——————————– ↓ ↓
Secondary 1st
Oocytes polar
(23, X) body
( 23,X )
↓
Ovulation
↓
↓ ↓
Not fertilized
Fertilized ↓
↓ Complete
Degeneration Sec
Under meiotic
24 Division
↓ ↓
Female Sec
Pronucleus polar
(23,x) body
( 23,x) Spermatogenesis
Spermatogenesis
The development of spermatid from the primordial male germ cell and its subsequent differentiation into spermatozoa is called spermatogenesis. That is, the development and maturation of sperm is called spermatogenesis.
Before puberty, primordial germ cells develop into spermatogonia through the process of mitosis and then remain in the seminiferous tubules.
Spermatogonia then differentiate into primary spermatocyte (46,XY / diploid) through the process of mitosis. which remains for a long time in the profession of the first meiotic division.
Each spermatocyte contains 22 pairs of autosomes and one pair of sex chromosomes such as XY.
With the completion of the first meiotic division, the formation of two secondary spermatocytes (haploid) occurs. And it contains equal number of cytoplasm and haploid number of chromosomes. Like,
23 X, or 23 Y.
Immediately after the second meiotic division, four spermatids (without tail sperm cells) are formed. It contains chromosomes in haploid number viz.,
Two 23 X, two 23 Y.
After the formation of spermatid, morphological changes occur without further cell division which convert into spermatozoa.
This process is called spermatogenesis.
In male, it takes approximately 61 days to develop from spermatogonium to mature spermatozoa.
•> Chart presentation of spermatogenesis
Spermatogenesis
↓
Germ cell
↓Mitosis
Primary spermatocyte
( 46, XY )
↓
Fast meotic
division
↓
Secondary spermatocytes
↓
‐‐—————-
↓ ↓
23,X 23,Y
| |
↓ ↓ ↓ ↓
23, 23, 23 23
X X Y Y
\ | | /
↓
Spermatids
↓
Morphological changes
To Spermatozoa (Spermatogenesis)
Ovulation:
Ovulation i.e. the process of release of secondary Oocytes from mature Graafian follicle is called Ovulation.
The process of development and release of mature ovum is called ovulation.
Generally, women have a menstrual cycle of 28 days and ovulation usually occurs in the mid period of the menstrual cycle. That is, ovulation occurs on the 14th day.
The process of ovulation starts during the menarche i.e. the first menstrual cycle of a woman and this process stops with the menopause period itself. That is, the process of ovulation lasts from menarche to menopause period.
Normally only one secondary oocyte is released from one ovary.
Gametogenesis:
The maturation of two specialized cells like spermatozoa in male and ovum in female before forming a unit called zygote is called gametogenesis.
•> Ovum:
The ovum is the largest cell of the female body.
And the smallest cell is the platelet cell.
The size of the ovum is 120-150 μm.
The lifespan of an ovum is 12 to 24 hours.
Ovum formation takes place in 6-8 days.
Ovam Ma,
Nucleus, cytoplasm,
First polar body,
Zona pellucida (hyaluronic acid),
Corona radiata
There are such patches.
•> Sperm:
Sperm is the smallest cell in the male body.
The largest cell in the brain is the neuron.
The size of sperm is about 50 μm.
Its life span is 48 to 72 hours.
The formation time of spam is about 61 days.
Sperm na pats ma
head,
nucleus,
Acrosomes
(Hyaluronic Enzyme),
neck,
Mitochondria (power house) are located in the middle layer.
And there is also a trail of tail.
Fertilization:
Fertilization is a process in which the male reproductive cell spermatozoa fuses with the female reproductive cell ovum in the emmulla part of the fallopian tube and fertilization takes place leading to the formation of a zygote. Fertilization is mostly timed around ovulation
occurs in
An ovum is released from the ovary of the female reproductive system and this mature ovum is captured by the fimbriae of the fallopian tube. Then the ovum is transported to the ampulla part of the fallopian tube by the peristalsis movement of the fallopian tube and the ciliary muscles present in it. And it lasts from 12 to 24 hours.
During this time, the cervix secretes alkaline mucus due to the effect of estrogen which attracts sperm. During intercouse, about 60 to 120 million sperm are deposited in the posterior fornix of the vagina.
Many of which enter the fallopian tube by the cervical action and their propellant action, while the remaining sperm are destroyed by the acidic medium of the vagina.
A sperm cell can survive in the cervix for 48 to 72 hours if ovulation has not occurred.
These sperm cells are transported from the cervical area and transferred to the fallopian tube during this journey many sperm cells are destroyed and only thousands of sperm reach the fallopian tube and reach the ovum in the ampulla.
When the sperm reaches the ovum, the sperm has to form its own environment. That is, the sperm needs an alkaline environment. And if there is an acidic environment, the sperm is destroyed.
But, the environment outside the ovum is acidic due to hyaluronic acid.
Now, in order to convert this acidic environment into an alkaline environment, there is an acrosome layer at the tip of the sperm head, which contains the hyaluronic enzyme that has an alkaline environment. It secretes around the ovum.
Thus, the hyaluronic enzyme released from thousands of sperm simultaneously destroys the corona radiata (outer layer of the ovum). It then softens the zonapellucida layer so that the sperm can penetrate the zonapellucida and enter the ovum.
Oelema is present on all sides of the zona pellucida. But only one sperm can enter an egg.
Among them, the most mature and developed sperm penetrate through the zona pellucida layer.
Then the zona pellucida layer becomes bone, which is called zona hardening.
Cortical granules are deposited to fill the ulema penetrated by the sperm and fill the penetrated area. The ovum then becomes sealed. Due to this, other sperm cannot enter, and the tail of the sperm remains outside. goes
Now, the fusion of the sperm entering the ovum and the nucleus of the ovum is called fertilization and then due to this fertilization the formation of the zygote takes place
Implantation:
Implantation is the process in which the zygote is engaged in the development of the zygote from the fallopian tube into the endometrium of the uterine cavity.
The process of implantation starts from 4 to 5 days after the formation of the zygote and is completed by 11 days.
After the formation of the zygote, the zygote remains in the fallopian tube for four days and then implants in the uterine cavity. During these four days, division of cells takes place and along with the development of the intra-uterine wall, due to which the implanting egg can get a proper environment for its development.
Zygote with 46 chromosomes with zona pellucida cover undergoes first mitotic cell division in 2 cell stage by cleavage within 24-30 hours called blastomere.
After formation of zygote, within 40 to 50 hours, two cell division to four cell division takes place.
Then within 72 hours after zygote formation, 4 cell divisions to 8 cell divisions take place.
Then 16 cell divisions take place in 96 hours after zygote formation. After the cell divides, it forms a bunch-like structure called a morula. The morula is covered by the zona pellucida layer.
All these stages are completed in four days i.e. implantation starts from the 5th day and is completed by the 11th day.
During these four days cell division takes place and also the endometrium layer of the uterus also develops due to which the implanting egg can get a properly favorable environment for its growth and development.
After the formation of the zygote, the zygote remains in the fallopian tube for four days, after which the journey of the zygote starts on day 4 to 5 and reaches the uterus by day 11.
After the formulation of morula, there is collection of fluid in its cell due to which the size of the cell also enlarges which is called blastocyst.
After the formation of the blastocyst, all the cells have their own individual mucus covering.
Now when each cell develops its own individual mucus covering, the zona pellucida layer starts to disappear, this process is called zona hatching.
Now after the zona pellucida layer of the blastocyst disappears, some cells of the blastocyst form the outer layer and some cells collect in a site within the outer layer.
So the outer cell layer is called the outer cell mass and the collection of cells collected at a site within the outer cell layer is called the inner cell mass.
Outermost of the inner cell mass is a single layer of cells called the trophoblast.
When the blastocyst enters the uterus, it remains free for two to three days, after which the trophoblast part remains on the inner cell mass, then it sticks to the sticky endometrium, then it secretes an enzyme that eats away the epithelium there. The blastocyst implants in the endometrium which is also called nidation (embedding) which is usually completed by day 11 after fertilization.
Implantation occurs mostly in the posterior uterine wall but sometimes in the anterior wall of the fundus.
From this outer trophoblast the placenta and chorion and the inner cell mass form the placenta, amnion and umbilical cord.
Post implantation changes in uterus
Decidua:
Endometrium in pregnancy is called decidua.
As the secretion of estrogen increases, the thickness increases 4 times and the size of the blood vessels increases due to progesterone. It becomes a soft, vascular and spongy bed, in which the fertilized ovum implants. After birth the deciduas are shed except for the zona basalis.
Latin v. decidus
Mince falling off.
Area of Decidua:
There are three areas of decidua.
1) Decidua basalis:
The lower implantation site of the embryo is called the decidua basalis. which is immediately above the myometrium. which remains unchanged. It contributes to the placenta.
In parparia, it forms neoendometrium.
2) Decidua capsularis:
The superficial layer covering the rest of the embryo is called the decidua capsularis.
Decidua capsularis upsi ne decidua during fetal growth
parietalis
joins together.
3) Decidua
Parietalis or Deciduas Vera :
The lining of decidua in uterine cavity is called decidus vera.
Layers of Decidua:
There are three layers of decidua.
1) Basal layer:
This layer lies immediately above the uterine muscles. It is formed from the base of the endometrial glands and does not undergo changes. When the placenta separates, the base of the gland remains and the new endometrium is formed from it.
2) Spongy layer:
This spongy layer lies above the basal layer. It has dilated glands and enlarged blood vessels.
Chorionic villi invade this layer to form the placenta. A fibrous layer is formed in the dip part of this layer. It is called perforation layer or layer of Nitabuch. From this point the placenta separates from the uterine wall.
3) Compact layer:
This is the surface layer of the decidua. It is located near the KVT where the neck of the glands is densely packed with decidual cells.
Decidual cells are large and contain glycogen.
Function of Decidua:
Provides good space for implantation of blastocyst.
Provides nutrition to the ovum in the initial stage.
Prevents dip penetration of trophoblast.
Contributes to the formation of the basal plate of the placenta.
Development of Fertilized Ovum:
After the blastocyte is embedded in the endometrium, a layer of outer trophoblast is formed over the area.
Then three layers are formed.
1) Outer syncytiotrophoblast (syncytium):
Syncytiotrophoblasts erode the walls of blood vessels. And maternal blood makes nutrients for the embryo to develop.
2) Inner Cytotrophoblast:
Cytotrophoblast is a single layer of cells. Produces human chorionic gonadotrophin (HCG), which informs the corpus luteum that there is a pregnancy.
The corpus luteum continuously produces estrogen and progesterone.
Progesterone thickens the consistency of the deciduas, so menstruation does not occur. High levels of estrogen prevent the production of FSH.
3) Primitive mesenchyme or mesoderm:
The third layer mesoderm develops with its mammary as chorionic vesicles called the chorion. It forms the body stalk and umbilical cord. Then the embryo is connected to the chorion.
•> Finger like buds of trophoblast occur on the outer surface of the embedded blastocyte. It is called chorionic villus.
Types of chorionic villi are as follows.
1) Primary market:
A solid trophoblastic layer is formed on day 12 of fertilization.
2) Secondary distribution:
By day 16, a mesenchymal lining is formed with proliferation.
3) Tertiary distribution:
On day 21, blood vessels form with secondary proliferation.
The branches of the branching of the wall on the side of the uterine wall form the chorion frondosum and form the placenta. The chorion disappears due to the atrophy of the wall on the side of the uterine cavity.
The placenta and chorion are formed from blasts from the trophoblast while the inner cell mass forms from the placenta.
It has three layers:
1) Ectoderm
2) Mesoderm
3) Endoderm
1) Ectoderm:
Nervous system and skin are formed from ectoderm.
2) Mesoderm:
Heart, blood vessels, liver, pancreas, bone, muscles and some internal organs are formed from mesoderm.
3) Endoderm:
Mucous membrane and glands are formed from ectoderm.
In short:
blastocyte
↓
↓ ↓
trophoblast inner cell
↓ Mass
—————— ↓
↓ ↓
Play Kori
Santa Yon
•> Inner cell mass
↓
↓ ↓ ↓
Fits amnion ambe
Lick
Coda
Embryo:
This stage of organ development is the developing offspring up to 8 weeks after implantation called the embryo.
8 Offspring from wick to term is called fitus.
A fertilized egg goes through three stages of development by the time it hatches.
1) The Stage of Zygote (Before Implantation)
2) The Stage of Embryo (Early in Pregnancy)
3) The Stage of Fits (Later in Pregnancy)
The growing organism from 2nd to 8th week is called embryo.
During this period it develops from tiny cell clusters to 1 inch in length. During this time the play center develops between the embryo and the uterus.
The embryo is connected to the placenta by the umbilical cord.
The placenta acts as a filter and barrier. Through it, the embryo takes food and oxygen from the woman’s blood and removes Co2 and other waste products. These two blood systems are completely separate.
In the 1st month of life the human embryo is like any other animal but in the 2nd month it assumes human features. Like Face, Mouth, Legs, Fingers, Toes and Sexual Organs are undifferentiated (same for male and female).
When it is fully identified as clearly human, it leaves the embryo stage and enters the fitus stage.
Post Fertilization Events:
0 hour -> Fertilization,
24 hours -> 2 cell stage of zygote (blastomere),
42 hours -> 4 cell stage of zygote,
72 hours -> 12 cell stage of zygote,
96 hours -> 96 cell stage.Morula enters uterine cavity.
5th Day-> Blastocyst.
7th day-> implantation.
11th day -> implantation is complete.
12 th Day-> Primary Vili.
16th Day-> Secondary Vili.
21 St Day -> Tertiary Vili.
21-22nd Day-> Fital Heart, Fito Placental Circulation.
21- 40 day -> Chorion frondosum.
45 – 50 days -> cotyledons.
71-267 Day->fital stage
Development of Fits (According to Vic)
4 Vicks->
Ovum diameter 2 cm,
Embryo length 1 cm.
Covered from April.
Head, tail and lip buds develop.
8 Vicks->
Ovum-diameter 5 cm,
Fits length 2.5 cm.
Nose, external nose, fingers and toes develop.
And the head above the chest
is bent.
12 Vicks->
Ovum diameter 7.5 cm.
Fits length 8 cm.
The placenta forms, the cord twists, more features appear in the external ears,
Closed eyelids and nails.
16 Vicks->
Fits length 18 cm.
Eyes closed, skin red and transparent, external genital area recognizable.
20 development->
Feet length 25 cm.
Hair and lanugo (fine hair on the skin).
24 Vicks->
Fits length 30 centimeters cm.
Eyelids become detached, eyebrows and ilesis are seen.
28 Vicks->
Fits length 35 cm.
Weight – 1250 gm.
The skin begins to become a red, lanugo-covered subcutaneous fat,
The testes descend and the fitus becomes viable.
32 Vicks->
Fits length is 40 cm.
Weight is 1500 gm.
The nails reach the end of the finger and the skin appears less red.
Subcutaneous fat increases,
The cassia of the bride is present and the wrinkles are less visible.
36 Vicks->
Fits length 45 cm,
Weight-2500 gm.
Skin is pink, increased vernix, few lanugo, subcutaneous fat increases.
40 Vicks->
Feet Length 50 Cm.
Weight 3500 gm.
Skin becomes pink, lanugo disappears, vernix diminishes. Subcutaneous fat increases. Skull bone and testes come into the scrotum.
According to Trimester:
1) First Trimester (First Three Months):
The embryo from the fertilized ovum undergoes the following changes:
All organs are formed and heart starts beating in 21 to 22 days.
After the embryonic period, fitters are less at risk from drugs and infections.
Facial features form, brain develops rapidly and the head becomes larger than the body giving a human appearance.
External sex organs are visible but the sex cannot be identified.
Neck is tidy, nail beds start, nose, mouth, eyelids visible and tooth birds form.
A small amount of urine is released from the rudimentary kidney into the amniotic sac.
There is movement of part of limbus but not strong.
Fits length is about 2.9 inches and weight is 14 gms.
2) Second Trimester (4 months, 5 months to 6 months):
A fetal heart sound is heard through a stethoscope, ice closes and body growth increases.
Vernix Cassiosa protects delicate skin. The skin is wrinkled, transparent and pink.
Sex can be differentiated.
Small baby, uterus moves frilly.
Skeletal calcified.
Average crown sump length is 20 cm and weight is 568 gm.
3) Third Trimester (7 months, 8 months to 9 months)
Skin is pinkish white, strong sucking reflex, and ice can open and close.
Skull forms, hair appears.
The skull bone forms, at the closure of the suture line.
•Lightning.
Length-48-53 Cms,
Weight is 3000 gm.
Placenta:
Introduction
Placenta is a mass like structure. It usually develops in the anterior or posterior side of the upper uterine segment from two sources namely the fetal component chorion frondozum and the maternal component decidua basalis.
The placenta is connected to the fetus through the umbilical cord and the pregnancy is maintained. The placenta supports the life of the embryo by providing oxygen and food to the embryo and removing toxic materials.
Definition
The placenta has a “discoid shape” due to its septum.
It is “hemochorionic” because its chorion comes into direct contact with maternal blood, and it is “deciduous” because the placenta sheds off after birth.
Placenta origin
The placenta originates from the trophoblastic layer of the fertilized ovum.
The patient is closely linked to the mother’s circulation to properly perform functions that the fetus is unable to perform during intrauterine life.
The survival of the fetus depends on the integrity and efficiency of the placenta.
Attachment of placenta
The placenta is attached to the uterine wall of the mother and is the bond between the mother and the fetus.
Placenta at Fultma
At most the placenta is a disc-like spongy, fibrous structure that is flat and round or oval in shape. The placenta is thick in the center and thin at the edges.
Diameter and thickness of placenta
1)Average weight of placenta a:=
500 grams
2) Ratio between fetus and placenta := 1/6( 3kg / 500 gm).
3) Diameter of placenta a:= 15-20 cm.
4)Surface area of placenta:= 243 sq cm
(square centimeter).
5) Volume of placenta A:= 500 ml.
6) Placenta is thick in the center while thin at the edges.
Center Path of Placenta:=
2.5 to 3 cm.
Peripheral tract of placenta :=
1 to 1.5 cm
The umbilical cord connects the fetus to the placenta with an umbilical vein and
There are two umbilical arteries.
Part of placenta
The placenta has two surfaces.
1) Fetal surface (80%),
2) Maternal surface (20%)
1) Fetal surface (80%):
The fetal surface is smooth, sinuous and transparent, covered by a smooth and glistening amnion.
In which the umbilical cord is connected at the center.
Umbilical vessels are seen on this surface.
The fittal surface is bright red in color.
2) Maternal Surface (20%):
Maternal surface is “rough and spongy”.
It is dull red in color.
The maternal surface is divided into 15 to 30 cotyledons separated by sulci.
A small calcified infract appears on the maternal surface.
Structure of placenta
The placenta consists of two plates. The chorionic plate lies inward and is covered by the amniotic membrane. The umbilical cord is attached to this plate. On the maternal side there is a basal plate.
The intervillous space lies between the chorionic plate (fetal site) and the basal plate (maternal site).
In this intervillous space, the stem cell and its branches are located and the maternal blood is located in this space.
1) Amniotic membrane
Amniotic membrane is a single layer of cubical epithelium and connective tissues. And the amniotic membrane is loosely attached to the chorionic plate.
It has no part in placenta formation.
2) Chorionic plate
The chorionic plate is the seat of connective tissue. It contains branches of umbilical vessels. The chorionic plate is covered by the amniotic membrane at the fetal site.
Stem cells arise from the chorionic plate that forms the inner boundary of the choriodecidual space.
3) Basal plate.
The basal plate is formed from cytoblasts, syncytoblasts, and decidua basalis.
It is a compact and spongy layer.
A basal plate is present nearer the maternal surface.
The uterine artery and vein enter the intervillous space from the basal plate.
The basal plate forms the boundary at the maternal surface.
4) Intervillous space
It has chorionic plate on the inner side and basal plate on the outer side. There is a connection of two plates around.
Internally all sides are lined with syncytotrophoblasts and filled with slow flowing maternal blood.
In this intervillous space are the stem cells and their branches.
5) Stem branching
Stem cells arise from the chorionic plate and extend to the basal plate.
Primary, secondary and tertiary divisions are formed in progressive development.
The functional unit of the placenta is the fetal cotyledon or placentome. It is formed from major primary stem villus.
These major stem villi pass through the intervillous space and anchor in the basal plate. The functional subunit is called the lobule, which is formed from the tertiary villi.
There are about 60 stem cells in the human placenta. Hence each cotylodon (total :=15-20) has three to four major stem branches. Some villi anchor the placenta and some remain free in the intervalsal space called nutritive villi. The blood vessels in the villi do not connect with each other.
Circulation through the presenta
There are two types of circulation in the placenta.
1) Phyto Placental Circulation,
2) Uteroplacental circulation
1) Phyto Placental Circulation,
Two umbilical arteries in the phytoplacental circulation bring impure blood from the placenta and enter the chorionic plate, each supplying 1/2 of the placenta.
The arteries break into small branches and enter the stem of the chorionic villi, which divide into primary, secondary, and tertiary vessels. Maternal and fetal blood flow side by side in opposite directions.
Fetal blood flow is 400 ml/minute which is mainly due to the pumping action of the fetal heart rate. Blood from the umbilical artery delivers carbon dioxide to the placenta and absorbs oxygen and returns to the fetus through the umbilical vein.
2) Uteroplacental Circulation (Maternal Circulation)
In the uteroplacental circulation, uterine arteries and veins enter the intervillous space through the basal plate and transmit blood and nutrients from the mother to the intervillous space.
Function of placenta
1) Respiratory function
The fetus receives oxygen and excretes carbon dioxide through the placenta.
Just as oxygen from the mother’s blood passes into the fetal blood, carbon dioxide in the fetus is transmitted to the maternal blood through the placenta.
2) Nutritive function
All types of nutrients such as amino acids, glucose, vitamins, minerals, lipids, water and electrolytes are transmitted from the mother to the fitters.
Food taken in the maternal diet reaches the placental side where it is converted into simple form, then the placenta selects the substances required by the fetus and transmits them to the fetus.
3) Storage function
Placenta stores glucose, iron and vitamins. And the placenta provides it when the fetus needs it.
4) Excretory function
The waste product in the fetus is transmitted to the placenta.
5) Protection
Placental membrane has limited barrier function. Some of the antibodies passed from the mother to the fetus provide immunity to the baby for up to three months after birth.
6) Immunological function
Antigens from the fetus and placenta act as foreign to the mother. However, graft rejection does not occur because the placenta provides immunological protection against rejection.
7) Hormonal function
steroid hormones
estrogen,
Progesterone.
Protein hormones
HCG (Human Chorionic Gonadotrophin),
HPL (Human Placental Lactogen),
relaxin,
PAPPA (Pregnancy Associated Plasma Protein:= A).
•>HCG (Human Chorionic Gonadotrophin),
HCG (human chorionic gonadotrophin) is produced from the cytotrophoblastic layer of the chorionic villi.
HCG (human chorionic gonadotrophin) is high during 7 to 10 weeks of pregnancy then decreases as the pregnancy progresses it maintains the corpus luteum.
HCG (human chorionic gonadotrophin) is used in pregnancy tests because it is excreted in the mother’s urine.
HCG (human chorionic gonadotrophin) is detected in blood on day 7 and urine on day 9 after fertilization, which indicates a positive pregnancy test.
••> HPL (Human Placental Lactogen)
HPL (Human Placental Lactogen) is produced from the placenta and is involved in the lactogenic and metabolic processes of pregnancy. When the level of human chorionic gonadotropin trophin decreases, the level of human placental lactogen (HPL) increases and it continues in throwout pregnancy.
Human placental lactogen (HPL) works as an anti-insulin that increases blood glucose levels and helps supply glucose to the fetus.
••>Relaxin
Relaxin is produced by decidual cells. And it softens the cervix and helps the pelvic ligaments and symphysis pubis to relax the labor process.
••>PAPPA (Pregnancy Associated Plasma Protein:= A)
Pregnancy Associated Plasma Protein:= A works as an immunosuppressant and works to maintain pregnancy.
••> Estrogen
Estrogen is produced by the placenta in a throwout pregnancy. It is essential for welling of the phytoplacenta.
Estrogen increases during labor which helps release oxytocin which causes increased uterine contractions.
••> Progesterone
Progesterone is produced from the synovial layer of the placenta which works as a tocolytic agent and prevents uterine contractions as well as works as an immunosuppressant to help maintain the pregnancy.
Placental Abnormalities:
1) Placenta saccenturiata
2) Placenta spuria
3) Wellmentous placenta
4)Beteldor placenta
5) Placenta Membranacea
6) Placenta marginata
7) Placenta circumvallate
8) Placenta accreta
9) Placenta increta
10) Placenta percreta
11) Large placenta
12) Bipertite placenta
13)Tripartite placenta
14) Placenta fenestrata
15) Placenta previa
16) Abruptio placenta
1) Placenta saccenturiata:
Placenta secanturiata occurs when one or more of the placenta has extra lobes that are connected to the main placenta by blood vessels.
These extra lobes are not directly attached to the main placenta but are connected by a membrane.
These lobes are distant from the main placental mass, so there is a possibility that this secanturia lobe may be left in the uterus during expulsion of the placenta. Due to this, the condition of severe postpartum hemorrhage (PPH) can occur.
2) Placenta Spuria:
Placenta spuria, also known as “false placenta” or “accessory placenta”, is a condition of the placenta where there are one or more small, extra lobes of placental tissue separate from the main placenta.
which are located at different distances from the main placental margin. And the lobes do not have communicating blood vessels.
3) Wellmentous placenta:
In this, the umbilical cord is usually attached to the membrane one to three inches from the placenta.
This means that the blood vessels of the umbilical cord have to travel far (placental membrane) to get nutrients from the placenta, and they have to travel without the protection of Wharton’s jelly.
Without easy access to nutrients from the placenta, the fetus develops more slowly.
Without the protection of Wharton’s jelly, the exposed blood vessels from the umbilical cord are more prone to rupture and bleeding.
It can cause APH (Antepartum Haemorrhage) during artificial or spontaneous rupture of membranes.
4)Beteldor Placenta:
In beteldor placenta the cord is attached to the margin of the placenta i.e. the umbilical cord is not in the center of the placenta.
If associated with low implantation of the placenta, vaginal delivery may lead to cord compression leading to fetal anoxia or death.
5) Placenta Membranacea:
It results from the failure of the decidua capsularis to come into contact with the cornea.
It has a very thin and large placenta that occupies no large area on the wall of the uterus.
In this, retained placenta is more likely to occur and manual removal becomes difficult
6) Placenta marginata:
Placenta marginata consists of a layer of double-folded amnion and chorion at the periphery of the placenta, forming a Whitish ring-like structure.
When this whitish ring coincides with the placental margin, it is known as placenta marginata.
7) Placenta circumvallate:
In this condition, an opaque ring (opaque ring) is seen on the surface of the fit of the placenta. It is formed by the posterior doublet of the chorion and amnion and may result in a membrane that forms near the center of the placenta, usually at the edge of the placenta.
8) Placenta accreta:
Placenta accreta is abnormal attachment of the placenta to the uterine wall.
In other words, the placenta is attached to the myometrium.
9) Placenta increta:
Placenta increta develops into the deep layer of the myometrium in the placenta.
10) Placenta Percreta:
In placenta percreta, the placenta develops up to the perimetrium layer of the uterus.
11) Large placenta (more than 500 g):
A large placenta, often referred to as placental hypertrophy, is a condition where the placenta is significantly larger than is typical for the stage of pregnancy. It is associated with various maternal or fetal conditions such as maternal syphilis, diabetes mellitus, etc.
12)Bipartita placenta (dimidiata/bilobed):
bipartita (dimidiata)
In this condition, there is incomplete separation of the placenta into two separate lobes.
The umbilical vessels extend from one lobe to the other before uniting to form the umbilical cord.
13)Tripartite placenta:
In tripartite placenta the placenta is divided into three distinct parts i.e. there are three complete lobes of the placenta.
14) Placenta fenestrata:
Placenta fenestrata is a rare condition in which the central portion of the discoid placenta is missing. Rarely, actual in the placenta.
There may be a hole, but more often the defect involves villous tissue, and the chorionic plate remains intact.
It causes division of the placenta into two lobes. This is a rare condition.
15) Placenta Previa:
When the placenta partially or completely implants near or above the internal os of the lower segment of the uterus it is called “placenta previa”. 1/3 of cases of antepartum hemorrhage are due to placenta previa.
16) Abruptio Placenta:
Abruptio placenta is a form of antepartum hemorrhage (APH) in which a normally situated placenta prematurely separates from the uterine wall. And this causes bleeding which is called abruptio placenta.
Amniotic Fluid (Liquor Amni):
Definition:
Amniotic fluid is “the faint, slightly alkaline, colorless and watery contents of the amniotic sac in which the embryo-phytes grow.”
Amniotic fluid, or liquor amni, is the fluid in the amniotic sac that covers the developing fetus during pregnancy. And it is essential for the development and protection of the fetus.
It is believed to be a secretion of amniotic cells. Maturation and transudates of the placenta and maternal vessels, as well as the cord placenta and decidua, are thought to increase the quantity of amniotic fluid.
Origin:
Its origin is not clearly understood. Its origin is due to mixed maternal and fetal conditions.
Development:
The origin of the amniotic cavity and its lining membrane, the amnion, occurs with the development of the inner cell mass. Amniotic fluid is contained in the amniotic sac. which surrounds the fetus and is produced from the cells of the amnion. Transudates from fetal vessels in the placenta, placenta and maternal vessels from the deciduas. In the latter half of pregnancy its volume increases due to fetal urine. Fluid slowly fills the amniotic cavity and then fills the entire cavity.
Circulation:
The water in the amniotic fluid is completely changed and replaced every three hours. Because clearance of radioactive sodium occurs directly in the amniotic cavity.
The presence of lanugo and epithelium scales in the meconium indicates that the fluid is swallowed by the fetus and some passes through the intestine into the plasma.
Physical Characteristic:
1)Early Pregnancy:
Amniotic fluid is clear.
2) Mid pregnancy:
More bile pigments make it yellow.
3) Late Pregnancy:
Colorless as bilirubin becomes negligible,
Particulate matter, i.e. vernix caseosa and desquamated epidermis appear as white floccules.
Volume:
Amniotic fluid is detected during 8 weeks of pregnancy.
10 Vicks := 30 ml
12 Vicks:= 50 ml
20 Vicks:= 300 ml
30 Vicks:= 600 ml
36 – 38 Vicks:= 1000 ml
38 – 40 Vicks (at term):=600 – 800 ml
43 Vicks:= 200 ml.
Composition:
1) Early Pregnancy:
Amniotic fluid is similar to maternal plasma with less protein.
2) Late Pregnancy:
Amniotic fluid mixes with fetal urine, and desquamation occurs from the fetal skin.
Composition of Amniotic Fluid at Term:
1) Water:= 98 – 99%
2) Solid:= (Organic and Inorganic Cells):=1-2 %.
a)Organic:
i) Including protein (‘α’ fetoprotein) -0.25 gm%
ii) Uric acid – 4 mg%
iii) Creatinine – 1.8 mg.
iv) Glucose – 20 mg%
v) Lipids
vi) Phospholipids
vii) Bilirubin (trace)
viii) Hormones (prolactin)
ix)Vitamins
x) Prostaglandins.
B) inorganic
Electrolytes (Na, K, CI).
C) Sales
1). nucleated
2). Obtained from fetal skin, buccal mucosa, respiratory mucosa, bladder and umbilical cord are enucleated.
3).During mid-pregnancy, it contains large eosinophilic nucleated cells.
4).During late pregnancy, large enucleated cells and nucleated cells are seen in fetal skin.
Color
Early in pregnancy, it is colorless but near term it becomes a pale straw color due to the presence of exfoliated lanugo and epidermal cells from the fetus’s skin.
It may appear dirty due to the presence of vernix caseosa.
Abnormal color can be as follows:
1) Meconium Stained Green Color:
Present in conditions of fetal distress.
Thick if accompanied by the presence of flakes indicates chronic fetal distress.
2)Golden Color:
Due to Rh incompatibility
3) Greenish Yellow Color:
Due to post maturity
4) Dark Red Color:
Due to accidental haemorrhage
5) Dark Brown Color (Tobacco Color):
I.U.D (due to intra-uterine fetal death).
Functions:
The main function is to provide protection to the feet.
During pregnancy:
1) Amniotic fluid acts as a shock absorber and protects the fetus from external injuries.
2) It also works to maintain the temperature.
3) Amniotic fluid distends the amniotic sac. Hence the fitus provides space for growth and free movements. Also prevents adhesion between fetal parts and amniotic sac.
4) Nutritive value is negligible but provides adequate water supply to fitus.
During Labour:
Helps in dilatation of cervix.
Prevents blockage of placental circulation during uterine contractions.
It works to protect the placenta and placenta during uterine contractions.
Flushes the birth canal during the end of the first stage of labor and protects the fetus from its aseptic and bactericidal action. Also prevents ascending infection in the uterine cavity.
Clinical Importance
Through the study of amniotic fluid, information about the well-being of the fetus and maternity is obtained.
Intra-amniotic instillation is used as an abortion method using chemicals.
Aids in the assessment of fetal malformations, i.e. during 16-18 weeks, chromosomally defective babies can be identified by cell culture of amniotic fluid obtained by amniocentesis, e.g. Down’s syndrome. Enzyme deficiency is cultured. And amniotic fluid can identify metabolic errors in fits.
High levels of alpha-fetoprotein (AFP) in the amniotic fluid can lead to what is known as an open neural tube defect (anencephaly).
A low or high volume of amniotic fluid index (AFI) is assessed.
Rupture of the membrane and drainage of the liquid also helps in the induction of labour.
Umbilical cord:
Umbilical cord is also called “funish”.
“The funis or umbilical cord forms the connecting link between the fetus and the placenta”. through which fetal blood flows to and from the placenta.
The umbilical cord is connected between the fetus and the placenta, so the umbilical cord helps in providing blood flow to the fetus.
The umbilical cord extends from the fetal umbilical cord to the fetal surface of the placenta.
development
It develops from a stalk of a body of mesodermal tissue stretching between the disc of the fetus and the chorion.
Characteristic:
1) The length range of umbilical cord is 30 – 90 cm.
but,
Its average length is 55 cm.
2) Color := Bluish like white.
3) Diameter := 1-2.5 cm.
4)It is spirally twisted from left to right (40 twists).
5) Wharton’s jelly is located above the umbilical cord to provide protection to the cord.
6) Its thickness is not uniform but the cord has nodes or swelling at places. This swelling is due to dilatation of umbilical vessels or local collection of Wharton’s jelly. This swaying is also called false note.
7) Initially, two arteries and two veins form. Artery nu fitus has a connection with the internal iliac artery.
They carry venous blood (deoxygenated blood) from the fetus to the placenta.
Of the two umbilical veins that develop, the right vein disappears by the 16th week (fourth month), leaving one vein carrying oxygenated blood from the placenta to the fetus.
8) Umbilical arteries do not have an internal elastic lamina but have a well-developed muscular coat. This helps to effectively close the artery due to reflex spasm immediately after the birth of the baby.
Structure of Umbilical Cord:
1) Covering epithelium,
2) Wharton Jelly,
3) Blood vessels,
4) umbilical vesicle (yolk sac) and its vitelline duct no remnant (remnant),
5)Allantois,
6) Obliterated extra embryonic coelom
••>
1) Covering Epithelium:
Initially the umbilical cord is formed by a single layer of simple epithelium cells, but eventually a single layer of stratified epithelium forms.
2) Wharton Jelly:
It is composed of a gelatinous fluid formed from extra-embryonic mesodermal cells that is rich in polysaccharides and protects the umbilical vessels.
3) Blood Vessels:
Initially, two arteries and two veins form. The artery of the fitus has a connection with the internal iliac artery.
They carry venous blood (deoxygenated blood) from the fetus to the placenta.
Of the two umbilical veins that develop, the right vein disappears by the 16th week (fourth month), leaving one vein carrying oxygenated blood from the placenta to the fetus.
4) Umbilical Vesicle (Yolk Sac)
And no remnant of his vitelline duct:
The remainder of the yolk sac is attached to the placenta by the cord. It is seen there as a small yellow body or rarely.
Its proximal part persists as Meckel’s diverticulum.
5)Allantois:
A blind tubular structure is rarely seen near the femoral end. which reside within the fitus as continuous ureters and bladder.
6) Obliterated extra embryonic coelom:
In the initial period, the intraembryonic column is continuous with the extraembryonic column.
A congenital umbilical hernia or exomphelos remains if the condition persists.
Function:
It works as a life line between the placenta and fetus. It provides oxygen and nutrients to the fetus and transports the waste products of the fetus to the placenta.
The umbilical cord exchanges fluid and electrolytes between the umbilical vessels and the amniotic fluid.
About 400 ml/min of blood flow through the cord stabilizes the softness of the cord.
There are no pain receptors in the umbilical cord so there is no pain while cutting the cord i.e. it is painless.
Abnormalities of Umbilical Cord:
“Cord abnormalities involve marked variations of the umbilical cord which include anatomical and physiological alterations in the umbilical cord such as abnormal length, occlusion etc. which may lead to disturbance in the phyto-placental circulation.”
Abnormalities of umbilical cord are as follows:
1) Short code
2) Long Cord
3) True Knot
4) False Knot
5) Loop of Cord (Cord Nu Loop)
6) True cyst of cord (True cyst of cord)
7) False cyst (false cyst)
8) Single umbilical artery
•>
1) Short code:
Commonly umbilical cord length is 30 to 90 cm but in condition of short cord the length of umbilical cord is less than 30 cm (12 inches) which is called short cord.
1) There can be no chords (accordia).
2) Breech presentation favors a short cord.
3) It causes abruptio placenta and uterine inversion.
Effects: May restrict fetal movement, cause cord compression, or cause complications during delivery.
2) Long Cord:
Long cord is a condition in which the length of the umbilical cord is more than 100 cm (40 inches).
It can be as long as 300 cm.
Effects:
A long cord can also develop knots and loops.
A long cord can also lead to the risk of cord accidents like cord prolapse.
A long cold can cover the neck of the fetus which can also lead to the condition of fetal distress.
3) True Knot:
The actual note formed in the umbilical cord by the mother moving around the fitus is called the true note.
True notes occur in 1% and are rare.
It is common in monoamniotic twins.
Perinatal loss increases threefold.
Implications: Cord compression can occur, potentially affecting blood flow and oxygen supply to the fetus.
4) False Knot:
Occurs due to tumors and developmental variations in vessels.
It is usually seen due to accumulation of Wharton jelly.
It features chords that resemble a note but is usually caused by normal variations in chord structure.
Effect: It is usually benign but can be mistaken for a true note.
5) Loop of cord
(loop of cord):
This is a condition in which the umbilical cord forms loops around the neck of the fetus.
Which are generally of three types:
1) A loop (loop) of cord around the neck of the fetus (21%).
2) Two loops of cord around the neck of the fetus (3.5%).
3) Three loops of cord around the neck of the fitus (0.2%).
Effects: May cause cord compression, affect fetal heart rate, and potentially complicate delivery.
6) True cyst of cord (True cyst of cord):
Caused by vestiges of vesicle or allantois.
A true cyst is a fluid-filled cyst that is lined by epithelium and lies within the umbilical cord.
Effects: May be benign but requires monitoring for possible association with fetal anomalies.
7) False Cyst (False Cyst):
Wharton’s jelly forms due to liquefaction.
Implications: False cysts of the umbilical cord are usually benign. Which gets resolved by itself. It does not cause any major fetal anomalies.
8) Single Umbilical Artery:
A single umbilical artery (SUA) is a condition where only one artery is present in the cord instead of the usual two umbilical arteries.
It occurs in up to 1% of cases. It is more common in twins and diabetic mothers.
It occurs due to congenital anomalies of the fetus.
A single umbilical artery increases the chances of abortion, prematurity, dysmaturity and perinatal mortality.
Fetal circulation
Fetal circulation is a unique circulatory system that is present in the developing fetus. When the fetus is in the womb (uterus), it is formed to fulfill the need of oxygen and nutrients.
Separate fetal circulation in embryos starts during the 16th post-fertilization day.
The fetal heart starts beating on the 21st day after fertilization. Also, the fetus in utero receives oxygen and nutrients from the placenta because its lungs and alimentary track are functional, so fetal circulation is the circulation through which the fetus receives oxygen and nutrients from the placenta for its survival.
Features of fetal circulation
1) Umbilical Code:
The umbilical cord contains two umbilical arteries and one umbilical vein.
Umbilical artery:
The umbilical artery transfers fetal waste products and deoxygenated blood from the fetus to the placenta.
Umbilical vein:
Umbilical vein
It transfers oxygenated blood and nutrients from the placenta to the feet.
2) Placenta:
The placenta acts as an interface between the circulatory system of the mother and the fetus.
The placenta works to exchange nutrients, oxygen and waste products between maternal blood and fetal blood.
As the placenta delivers oxygen and nutrients to the fetus through the umbilical vein and receives the deoxygenated blood and waste products of the fetus through the umbilical artery in the placenta.
3) Ductus Venous (vein to vein):
The ductus venosus is the conduit through which oxygenated blood passes from the umbilical vein to the inferior vena cava, bypassing the liver and digestive organs.
Because of this, oxygenated blood can reach the brain and heart of a fit in an adequate amount.
4) Foramen ovale (oval opening):
The foramen ovale is a fetal cardiac structure that is a small opening in the septum between the right atrium and the left atrium of the heart that acts as a conduit between the right atrium and the left atrium.
Due to this opening (sunt), the blood in the right atrium is shifted to the left atrium bypassing the fetal lungs.
This finding is important because the lungs of the fetus are functional during intrauterine life and are filled with fluid due to which the fetal lungs are not able to do their work properly.
5) Ductus arteriosus (artery to artery):
The ductus arteriosus is a vital vascular connection that is the communication (shunt) between the pulmonary artery and the aorta.
Due to this ductus arteriosus sunt, blood from the right ventricles bypasses the lungs and flows into the systemic circulation through the sunt.
Vital Circulation:
Oxygen diffuses from the maternal blood into the choriodecidual space (placenta), thus the placental wall and vessels unite to form the umbilical vein.
The umbilical vein from the placenta travels through the umbilical cord to the fetus.
The umbilical vein passes through the umbilical wall to form two branches of the umbilical vein.
A branch of the umbilical vein joins with the portal vein of the liver of the fetus and provides nutrients and oxygen to the liver of the fetus. Blood is collected from the liver through the hepatic vein and enters the inferior vena cava.
The 2nd branch of the umbilical vein is the main vessel called the ductus venosus. It directly connects to the inferior Venakawa.
Oxygenated blood in the umbilical vein mixes with deoxygenated blood from the lower leg and trunk in the inferior vena cava.
But Sirius does not significantly affect the oxygen content of the ductus venosus.
Blood now enters the right atrium through the inferior vena cava.
Then the blood in the right atrium goes to the left atrium through the foramen ovale, which is between the right atrium and the left atrium.
Then the blood in the left atrium goes into the left ventricle through the mitral valve.
Blood then exits the heart through the aorta in the left ventricle.
The coronary vessels of the aorta (coronary artery, brachiocephalic trunk (right common carotid artery, right subclavian artery, left common carotid artery, left subclavian artery)) supply blood to the branches of the heart and head.
Blood from the head and neck enters the right atrium through the superior vena cava and crosses the inferior vena cava into the right ventricle through the tricuspid valve.
Most of the blood from the right ventricle through the pulmonary artery bypasses the lungs (since the lungs are inactive) and passes through the descending aorta through the ductus arteriosus (no sunt between the pulmonary artery and the aorta) to supply blood to the abdominal organs and the lower lens.
The descending aorta then forms the right and left internal iliac arteries.
The right and left internal iliac arteries again divide into two hypogastric arteries.
The hypogastric artery enters the umbilical cord to form two umbilical arteries.
These two umbilical arteries bring deoxygenated blood back to the placenta.
Fit blood circulates fast and is constantly renewed.
Mean cardiac output in fit is 350 ml/kg/min.
Fetus Skull:
Introduction:
The shape of the fetal skull is ovoid or egg shaped. The fetal skull is the skeletal structure of the unborn baby. Certain changes are seen in the fetal skull during delivery.
The fetal skull provides shape for the brain and facial features to grow.
The femoral skull is made up of many bones, such as the frontal bone, parietal bone, temporal bone, and occipital bone along with other smaller bones such as the sphenoid and ethmoid bones. These bones are connected to each other by flexible joints called sutures. Which helps the child in head compression and slight movement during birth. There are also two soft fontanelles within the fetal skull which fuse after birth.
Fitus’ skull is somewhat compressible and is composed primarily of thin, flexible tabular (flat) bone that forms the vault.
It is anchored to the rigid and incompressible bone at the base of the bone.
Area of the femoral skull:
Fitus skull is divided into several zones of obstetrical importance. It is mainly divided into three parts.
such as,
1) Vertex
2) Bro
3) Face
•>
1) Vertex:
It is a quadrangular area
It is bound by:
a) Anteriorly (front):
through bregma and coronal sutures.
b) Posteriorly (back):
by the lambda and lambdoid sutures.
C)Laterally (Sidema):
by lines passing through the parietal eminence.
2) Bro:
It is the area bounded on one side by the anterior fontanel and coronal sutures and on the other side by the root of the nose and the supraorbital ridges (stripes) on both sides.
3)Face:
It is the area bounded on one side by the root of the nose and supraorbital ridges and on the other by the junction of the floor of the mouth with the neck.
Region of Skull:
The femoral skull is generally divided into six regions:
1) Vault
2) Base
3) Face
4) Vertex
5)Occiput
6)Sinciput or Bro
•>
1) Vault:
The vault is formed by the two parietal bones, the upper part of the occipital bone, the temporal bone and the frontal bone, it is the uppermost non-compressible part of the skull with a large dome shape.
•> Bones of Vault:
The skull vault contains the following bones:
a) Two frontal bones:
The frontal bones are located in the front of the skull. It is called forehead or sinciput.
Its center is called the frontal eminence. The frontal bone is separated by the frontal suture
b) Two parietal bones:
Between the frontal bone and the occipital bone, the parietal bones lie on either side of the skull. It forms the superior and lateral aspects of the skull.
The two parietal bones of the skull are separated from each other by a sagittal suture running from front to back.
C) Two temporal bones:
The temporal bone lies below the parietal bone at both sites of the skull. It consists of inner and middle ear
d) An occipital bone:
The occipital bone is located at the back side of the head forming the occiput region. which is part of the base of the skull. It contains the foramen magnum that protects the center of the spinal cord as it exits the skull.
Occipital protuberance
is called
2) Base:
It is the lowest part that provides protection to the vital center in the medulla. It is composed of firmly united bone.
3)Face:
It is the area bounded on one side by the root of the nose and the supraorbital ridges and on the other by the junction of the floor of the mouth with the neck.
4)Vertex:
There is an area bounded anteriorly by the anterior fontanel, laterally by the two parietal eminences, and posteriorly by the posterior fontanelles.
5) Occiput:
It is the area from the posterior fontanel to the foramen magnum.
6) Cinciput or Brow:
It is bounded anteriorly by the orbital region and posteriorly by the coronal suture and is composed mainly of frontal bone.
Landmarks of Fittal Skull:
1)Occiput,
2) lambs,
3) Vertex,
4)Priter Eminence,
5) In Bragg,
6) Cinciput,
7) Glabella,
8) Nason,
9) Mentum
Sutures and Fontanelle:
The flat bones of the vault are held together by a non-ossified membrane attached to the margins of the bone. These are called sutures and fontanelles. The area in front of the anterior fontanel and corresponding to the area of the brow is called the synciput.
Sutures:
Sutures are cranial joints and are formed when two bones meet. They are made of fibrous tissue that allows mobility between the cranial bones. There are usually four sutures in the vault.
1) Sagittal or longitudinal suture
2) Coronal suture
3) Frontal suture
4) Lambdoid suture
•>1) Sagittal or longitudinal suture:
The sagittal suture lies between the two parietal bones.
2) Coronal suture:
The coronal suture is between the frontal and parietal bones on either side of the head.
3) Frontal suture:
The frontal suture is located between the two frontal bones.
4) Lambdoid suture:
There are two lambdoid sutures. Each suture is on both sides of the head on the upper margin of the parietal bone and the occipital bone. Its sep is like the Greek letter lambda ( λ ).
Importance:
Sutures help in overlapping and molding the bones during labor, which is important when the head passes through the pelvis during labor.
Palpating the sagittal sutures during internal examination in labor gives an idea of the degree of engagement, internal rotation and molding of the head.
Fontanelles:
Between the skull bones there is a wide gap between two sutures called fontanelles.
Fontanelles are non-ossified membrane spaces formed by the joining of two sutures.
There are six main types of sutures.
such as,
1) two anterolateral or sphenoid fontanels,
(between parietal, temporal and frontal bones)
2) two posterolateral
or or mastoid bone (between the parietal, temporal and occipital bones),
3) An anterior fontanelle
4) A posterior fontanel
Thus, there are a total of six fontanelles.
Two of them are Fontanelles namely, 1) Anterior Fontanelle/Frontal or Bregma and
2) Posterior fontanel/occipital or lambda is important in obstetrics.
•>1) Anterior fontanel/frontal or (bregma):
Anterior/frontal or bregma suture A, •Anteriorly:= frontal sutures
•Posteriorly:= sagittal sutures and
•At both sites:= Coronal sutures are formed by the joining of four sutures into the anterior fontanel or Bragg.
Its shape is like a diamond (🔹).
Its anterior-posterior diameter:= 4 cm and transverse diameter:= 2.5 cm.
The time for ossification (close) of the anterior fontanel is 16 – 18 months
Importance:
Palpation of the head during internal examination reveals the degree of flexion of the head.
Molding of the head can be done.
Helps in brain growth.
Palpation of the floor gives an idea of the intracranial status.
Example: Depression in dehydration and elevated intracranial tension.
Occasionally, the superior longitudinal sinus is used for blood collection and exchange transfusion.
•The lateral angle of the anterior fontanelle is rarely used to collect CSF from the lateral ventricle.
2) Posterior Fontanel/Occipital or (Lambda):
Posterior Fontanelle The joining of anteriorly sagittal suture and lambda sutures on both sides forms the posterior fontanel or longus.
It is of triangular shape ( 🔺️ ).
Its size is 1.2 × 1.2 cm.
Its ossification time is one and a half months (6-8 weeks).
•> Diameter of femoral skull:
Anterior posterior diameter
1) Suboccipito Bagmatic:=
9.5 CM,
From the lower part of the nape of the neck to the center part of the bregma (anterior fontanel).
2)Suboccipito frontal:= 10 CM
From below the nape of the neck to the anterior end of the anterior fontanel or to the center part of the syncytium.
3) Occipito Frontal:= 11.5 CM
From the occipital eminence to the root of the nose i.e. to the glabella.
4)Mentovertical:= 14 CM
Mentovertical diameter from the midpoint of the chin to the highest point of the sagittal suture.
5) SUBMENTO VERTICAL:= 11.5 CM
Submentum vertical diameter from the junction of the floor of the mouth to the highest point of the sagittal suture.
6) Submento Pragmatic:= 9.5 CM
Submento bregma from the junction of the floor of the mouth to the center of the lyre bregma (anterior fontanel).
Transverse diameter
1) Biparietal diameter:= 9.5 CM
Biparietal diameter is the diameter between the two parietal eminences.
2) Supra subparietal diameter:= 8.5 CM
From below the parietal eminence on one side to above the parietal eminence on the opposite side.
3) Bitemporal diameter:= 8.2 CM
Distance between anterior-inferior end of both coronal sutures.
4)Bimastoid diameter:= 7.5 CM
The distance between the tips of both mastoid processes.
Molding:
As the fetus passes through the birth canal, resistance from the birth passage in the head of the fetus causes alteration (changes) in the shape of the head of the fetus is called “molding”.
During normal delivery, Fitus’s skull usually changes by 4 mm, so there is no problem in the brain.
The bones of a newborn baby’s skull are soft and flexible, with gaps between the bone plates. The space between the plates of the bones of the skull is called the cranial suture. The anterior and posterior fontanels have two gaps that are particularly large. These tender spots are felt on touching the top of the baby’s head.
During head-first delivery, pressure on the head due to the narrowing birth canal (vagina and pelvic bones) can cause the head to mold into a rectangular shape.
This gap or space allows the baby’s head to change shape depending on the amount and length of pressure, the skull bones may even overlap. This gap or space allows the brain to grow within the bones of the skull. As the brain reaches its full size, they will close.
Mechanism:
Compression in the engaging diameter of the head increases the length of its right angle diameter.
Ex:= Engaging suboccipito bragmatic diameter in well flexed head in anterior vertex presentation compresses its right angle mento-vertical diameter increases.
During this process the parietal bone overlaps the adjacent bones such as the occipital bone at the back, the frontal bone at the front and the temporal bone at the side. The right parietal bone in the vertex overrides the left parietal bone. The molding disappears within a few hours after birth.
Grading:
Grade:= 1 (Bones touch each other but do not overlap).
Grade:= 2 (bones overlap but separate easily).
Grade:=3 (Bone is fixed overlapping).
Importance:
The shape of the molding can give an idea of the position of the fetal head in the pelvis.
Note: Severe intracranial disturbance in the head due to excessive fitting head molding may lead to rupture of the tentorium cerebelli or subdural hemorrhage.
Caput Sucadenium:
Accumulation of serosangenous fluid in the layers of the scalp causing edematous swelling is called caput sukkadenium. It is caused by the pressure of girdle of contact. It is either a bony pelvis, a dilating cervix or a vulval ring. Capt Sucadenium is also seen at birth. Swelling is boggy. And it crosses the suture line which disappears in 24-36 hours, mostly after membrane rupture.
Cephalohematoma:
A cephalohematoma is a condition in which a collection of blood occurs under the pericranium and flat bones of the head that cover the skull bones, usually unilaterally and over the parietal bones.
It is caused by rupture of a small emissary vein from the skull and may be associated with a fracture of the skull bone. This can occur due to forceps delivery but can also be seen after normal labor. Ventous application does not increase the incidence of cephalohematoma. It is never present at birth but develops slowly after 12-24 hours.
This swelling is limited by lines of sutures in the pericranium of the skull which are fixed to the margin of the bone, soft, fluctuant and incompressible.
It grows and disappears on its own after a few weeks i.e. approximately 6 weeks.
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