🌸 ANATOMY & PHYSIOLOGY OF FEMALE REPRODUCTIVE SYSTEM

🌷 1. Overview / Introduction

The female reproductive system consists of external and internal organs responsible for ovulation, fertilization, pregnancy, childbirth, and hormone production.
It works in coordination with the endocrine system and follows a monthly cyclic hormonal rhythm.

🩺 2. INTERNAL REPRODUCTIVE ORGANS

🥚 A. Ovaries

🌟 Main Functions Highlighted

• 👉 Oogenesis – formation and maturation of ova.
• 👉 Hormone secretion – estrogen, progesterone, inhibin.
• 👉 Support menstrual cycle & pregnancy.

📍 Structure & Location

• Two almond-shaped glands located on the lateral pelvic wall.
• Attached to the uterus by the ovarian ligament.

⚙️ Physiology

• At birth: ~ 1–2 million primordial follicles.
• Puberty: ~ 3–4 lakh follicles remain.
• Each cycle → one dominant follicle matures → ovulation occurs around day 14.
• Corpus luteum forms → secretes progesterone to prepare endometrium.

🌸 B. Fallopian Tubes (Uterine Tubes / Oviducts)

🌟 Main Functions Highlighted

• 👉 Transport ova from ovary to uterus
• 👉 Site of fertilization (ampulla)
• 👉 Provide nutrient-rich environment for gametes

📍 Structure

Divided into 4 parts:

• Fimbriae – pick up ovum
• Infundibulum
• Ampulla – fertilization site
• Isthmus – narrow part near uterus

⚙️ Physiology

• Tubes lined with ciliated epithelium → sweeps ovum forward
• Peristaltic movements assist ovum transport
• Secretions nourish sperm & zygote

🌺 C. Uterus

A hollow, pear-shaped muscular organ essential for implantation, pregnancy, labor & menstruation.

🌟 Main Functions Highlighted

• 👉 Menstruation
• 👉 Implantation of fertilized ovum
• 👉 Nourishes & protects fetus
• 👉 Labor contractions via myometrium

📍 Parts

• Fundus – top dome
• Body (Corpus) – major portion
• Isthmus – between body & cervix
• Cervix – neck of uterus

🧱 Layers

• Perimetrium – outer
• Myometrium – muscular middle
• Endometrium – inner; undergoes cyclic changes

⚙️ Physiology

• Endometrium thickens under estrogen & progesterone
• If no pregnancy → menstruation occurs
• During pregnancy → uterus enlarges, contracts at term

🌹 D. Cervix

🌟 Main Functions Highlighted

• 👉 Acts as gateway between uterus & vagina
• 👉 Produces cervical mucus (changes with cycle)
• 👉 Protects ascending infection
• 👉 Dilates during labor

📍 Anatomy

• Two openings: internal os & external os
• Lined by columnar epithelium in canal; squamous epithelium externally

⚙️ Physiology

• Estrogen → thin, watery mucus (fertile)
• Progesterone → thick mucus (non-fertile)
• Supports sperm passage during ovulation

🌷 E. Vagina

A muscular canal connecting cervix to the external genitalia.

🌟 Main Functions Highlighted

• 👉 Birth canal
• 👉 Outlet for menstrual flow
• 👉 Receives penis during intercourse
• 👉 Maintains acidic pH to prevent infection

📍 Structure

• 7–10 cm muscular tube
• Lined by stratified squamous epithelium
• Lubrication mainly from cervical mucus & Bartholin glands

⚙️ Physiology

• Acidic pH (3.5–4.5) due to lactobacilli
• Ensures microbial protection
• Becomes stretchy during delivery

🌼 3. EXTERNAL REPRODUCTIVE ORGANS (Vulva)

💠 A. Mons Pubis

• Fatty tissue over pubic symphysis
• Provides cushioning during intercourse

💠 B. Labia Majora

• Two large skin folds
• Protects internal genital structures

💠 C. Labia Minora

• Thin folds inside labia majora
• Rich in sebaceous glands
• Protects vaginal & urethral openings

💠 D. Clitoris

• Highly sensitive erectile tissue
• Equivalent to male penis
• Important for sexual arousal

💠 E. Vestibule

• Area containing openings of urethra, vagina, Bartholin glands

🌸 4. SUPPORTING STRUCTURES

🧵 A. Ligaments

🌟 Main Functions Highlighted

• 👉 Hold the uterus in position
• 👉 Prevent prolapse

Includes:

• Broad ligament
• Round ligament
• Uterosacral ligament
• Cardinal (transverse cervical) ligament

🩸 B. Blood Supply

• Uterine artery (branch of internal iliac artery)
• Ovarian artery (from abdominal aorta)
  Blood return through corresponding veins.

🧠 C. Nerve Supply

• Autonomic nerves (sympathetic & parasympathetic) regulate
  👉 uterine contraction
  👉 vaginal lubrication

🌺 5. PHYSIOLOGY OF MENSTRUAL CYCLE

🌟 Main Points

• Cycle length: 28 days (average)
• Controlled by hypothalamus–pituitary–ovarian axis

🌀 Phases

• Follicular phase → estrogen dominant, endometrial growth
• Ovulation → LH surge around day 14
• Luteal phase → progesterone dominant, prepares uterus
• Menstruation → shedding of endometrium

🌼 6. HORMONAL REGULATION

🌟 Key Hormones

• GnRH → from hypothalamus
• FSH → follicle growth
• LH → ovulation & corpus luteum
• Estrogen → secondary sexual characteristics, endometrial proliferation
• Progesterone → pregnancy maintenance, endometrial maturation

🌹 7. SECONDARY SEXUAL CHARACTERISTICS

Develop at puberty due to estrogen:

• Breast development
• Broadening of hips
• Growth of pubic/axillary hair
• Fat deposition pattern

🌸 8. REPRODUCTIVE PHYSIOLOGY

🌟 Important Highlights

Labor regulated by oxytocin + prostaglandins

Fertilization occurs in the ampulla

Implantation occurs in the uterine fundus/body

Pregnancy hormones maintain endometrium

Uterus enlarges up to 5–6 times due to pregnancy

🌸 FEMALE PELVIS

The female pelvis is a bony ring located in the lower part of the trunk. It provides support, protection, and forms the birth canal in females. Compared to the male pelvis, it is broader and designed for pregnancy and childbirth.

🦴 1. Definition of Pelvis

The pelvis is a basin-shaped bony structure formed by the two hip bones, sacrum, and coccyx.
In females, its architecture is adapted for reproduction, support of abdominal organs, and locomotion.

🧬 2. Bones Forming the Female Pelvis

The pelvis consists of four bones:

• 🦴 Two hip bones (Innominate bones)
• 🦴 One sacrum
• 🦴 One coccyx

Each hip bone has three fused parts:

• Ilium (upper flared part)
• Ischium (posterior–inferior part where body weight falls in sitting)
• Pubis (anterior portion forming pubic arch)

🧩 3. Divisions of the Pelvis

The pelvis is divided into two major parts:

🔹 a) False Pelvis (Greater Pelvis)

• Located above the pelvic brim
• Broad, shallow
• Supports abdominal organs like intestines
• Not part of the birth canal

🔹 b) True Pelvis (Lesser Pelvis)

• Located below the pelvic brim
• Narrow, deep
• Forms the bony birth canal
• Very important in obstetrics

🌼 4. Boundaries of True Pelvis

The true pelvis has three important obstetric areas:

⭐ a) Pelvic Inlet

• Also called Brim
• Upper opening of true pelvis
• Shape: Transversely oval

⭐ b) Pelvic Cavity

• Curved canal
• Smooth, round walls
• Size is crucial for fetal descent

⭐ c) Pelvic Outlet

• Lower opening of true pelvis
• Diamond-shaped
• Bound anteriorly by pubic arch
• Bound posteriorly by coccyx

🧠 5. Pelvic Diameters (Obstetric Importance)

Though we are avoiding tables, learn these key diameters descriptively:

⭐ Pelvic Inlet Diameters

• Anteroposterior diameter: Distance from sacral promontory → upper border of pubic symphysis
• Transverse diameter: Widest distance between farthest points of pelvic brim
• Oblique diameter: From sacroiliac joint to opposite iliopectineal eminence

⭐ Pelvic Cavity Diameters

• Almost round
• Uniform diameters

⭐ Pelvic Outlet Diameters

• Anteroposterior diameter increases during labour due to coccyx mobility
• Transverse diameter: Between ischial tuberosities (important for normal vaginal delivery)

👩‍🍼 6. Characteristics of Female Pelvis (Important for Obstetrics)

The female pelvis is:

• 🟣 Wider and shorter
• 🟣 Broader iliac blades
• 🟣 Oblique diameters equal
• 🟣 Pelvic inlet is transversely oval
• 🟣 Pubic arch is wide (greater than 80°)
• 🟣 Sacrum is shorter, wider, and more curved
• 🟣 Ischial spines less prominent – allows easy fetal descent

These special features help accommodate the fetus during delivery.

🧠 7. Types of Female Pelvis (Caldwell-Moloy Classification)

🔹 1. Gynecoid Pelvis (Ideal for childbirth)

• Round inlet
• Wide pubic arch
• Non-prominent ischial spines
• Best for normal vaginal delivery

🔹 2. Android Pelvis (Male type)

• Heart-shaped inlet
• Narrow pubic arch
• Prominent ischial spines
• May cause obstructed labour

🔹 3. Anthropoid Pelvis

• Oval inlet (AP diameter > transverse)
• Favorable for occipito-posterior positions
• Vaginal delivery usually possible

🔹 4. Platypelloid Pelvis

• Transversely wide
• AP diameter short
• Difficult engagement of head
• Vaginal delivery less common

🧩 8. Soft Tissues of the Pelvis

These structures complete the birth canal:

⭐ a) Pelvic Floor (Pelvic Diaphragm)

• Formed by levator ani and coccygeus muscles
• Supports pelvic organs
• Provides tone needed during pregnancy and labour

⭐ b) Cervix & Lower Uterine Segment

• Form part of the soft birth canal
• Dilatation and effacement occur during labour

⭐ c) Vagina

• Distensible muscular canal
• Adjusts during fetal passage

🧬 9. Functions of the Female Pelvis

• 🧘‍♀️ Support for pelvic and abdominal organs
• 🤰 Anchorage for uterus during pregnancy
• 👶 Forms the bony birth canal
• 🚶 Provides stability during walking
• 🦴 Protects internal reproductive organs
• 💪 Gives attachment to important muscles

🌹 10. Clinical/Obstetric Importance

• Shape and size of pelvis decide mode of delivery
• Narrow pelvis may lead to:
  • 🚨 Cephalopelvic disproportion
  • 🚨 Obstructed labour
  • 🚨 Need for C-section
• Assessment done by pelvimetry (clinical or radiological)

🩺 ⭐ Definition of Fetal Development

👉 Fetal development means the growth and maturation of the embryo into a fetus, starting from fertilization until birth (40 weeks).
👉 It involves cell division, tissue differentiation, organ formation, growth, maturation, and functional development.

🧪 I. STAGES OF PRENATAL DEVELOPMENT

1️⃣ Germinal Stage (0–2 weeks)

🌱 Begins with fertilization → zygote formation
🌱 Rapid cell division → morula → blastocyst
🌱 Implantation occurs in the uterus around day 6–7
🌱 Development of amniotic cavity and yolk sac starts
👉 Critical stage: failure of implantation causes early abortion

2️⃣ Embryonic Stage (3–8 weeks)

🧬 Most critical stage — organogenesis begins
🧬 Risk of congenital anomalies highest
🧬 Formation of germ layers:

• Ectoderm → skin, CNS, PNS, eyes
• Mesoderm → bones, muscles, CVS, kidneys
• Endoderm → respiratory & digestive systems

✨ Major developments:

• Week 3: Primitive heart tube beats ❤️
• Week 4: Neural tube closes, limb buds appear
• Week 5–6: Eye & ear formation, brain development
• Week 7–8: Face forms, fingers appear, major organs outlined

👉 After 8 weeks → embryo is now called a fetus

🤰 II. FETAL PERIOD (9–40 WEEKS)

📌 Characterized by growth, maturation, organ function development

🌼 THIRD MONTH (9–12 weeks)

✨ Face well-formed
✨ Eyelids fused
✨ External genitalia differentiate (sex identification begins)
✨ Fingernails, toenails start
✨ Kidneys produce urine
✨ Heartbeat detected by Doppler (10–12 weeks)

🌿 FOURTH MONTH (13–16 weeks)

🦴 Skeleton ossification
👶 Baby is more active
👁️ Eyes & ears move into correct position
🍽️ GI tract starts peristalsis
✨ Lanugo appears lightly

🌙 FIFTH MONTH (17–20 weeks)

🌬️ Quickening felt by mother (first fetal movements)
🦵 Limbs stronger
🌸 Lanugo (fine hair) fully present
❄️ Vernix caseosa starts forming
👂 Fetus responds to sound

🌞 SIXTH MONTH (21–24 weeks)

🫁 Alveoli formation begins
🧠 Rapid brain growth
🔊 Fetus hears outside sounds
✨ Skin is thin, reddish
👣 Fingerprints formed
⚠️ Age of viability starts around 24 weeks (with NICU support)

🌧️ SEVENTH MONTH (25–28 weeks)

🫁 Surfactant production begins
👁️ Eyes open & close
🌡️ Body temperature regulation improving
🫀 Rhythmic breathing movements
🎧 Can respond to voices, music

🌺 EIGHTH MONTH (29–32 weeks)

🐳 Rapid weight gain
🧠 CNS mature enough to control breathing to some extent
🦵 Baby frequently changes position
👀 Pupillary reflex present
🍽️ Iron stored in liver

🌕 NINTH MONTH (33–36 weeks)

🟣 Increased fat deposition
🟣 Strong movements
🟣 Skin becomes smooth
🟣 Fetus gains ½ pound per week
🟣 Lungs more mature

🌟 TENTH MONTH (37–40 weeks) — Full Term

👶 Baby fully developed
⬆️ Subcutaneous fat present
🫁 Lungs fully functional
🧠 Brain continues to grow rapidly
📏 Average length: 50 cm
⚖️ Average weight: 3–3.5 kg

SUMMARY

⭐ Organogenesis = 3–8 weeks
⭐ Sex identifiable = 12 weeks
⭐ Quickening = 18–20 weeks
⭐ Age of viability = 24 weeks
⭐ Surfactant production = 28 weeks
⭐ Maximum weight gain = last 2 months
⭐ Full term = 37–40 weeks

🌈 IMPORTANT STRUCTURES DEVELOPED DURING FETAL LIFE

🫁 Respiratory System

• Alveoli: 24 weeks
• Surfactant: 28–32 weeks
• Functional lungs: 36–38 weeks

🫀 Cardiovascular System

• Heartbeat: 3–4 weeks
• Murmurs detectable
• Fetal circulation via ductus venosus, ductus arteriosus, foramen ovale

🧠 Nervous System

• Neural tube closes: 4 weeks
• Brain folds develop by 12–20 weeks
• Myelination increases from 28 weeks onward

🍽️ Gastrointestinal System

• Swallows amniotic fluid
• Meconium production begins (16 weeks)

🦴 Musculoskeletal

• Ossification from 12 weeks
• Movements felt 18–20 weeks