• Structure of male reproductive organs

Structure of Male Reproductive Organs

The male reproductive system is designed to produce, maintain, and transport sperm and semen, as well as to produce male sex hormones. It consists of external organs and internal organs, each with specific functions.

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1. External Male Reproductive Organs

a. Penis

• Structure:
  • Composed of three cylindrical bodies of erectile tissue:
    1. Corpora Cavernosa (2): Paired structures on the dorsal side.
    2. Corpus Spongiosum: Surrounds the urethra and extends to form the glans penis.
  • Glans Penis: Enlarged, sensitive distal end of the penis.
  • Prepuce (Foreskin): Fold of skin covering the glans (removed in circumcision).
• Function:
  • Delivers sperm into the female reproductive tract.
  • Plays a role in urination.

b. Scrotum

• Structure:
  • A pouch of skin, connective tissue, and muscle that houses the testes.
  • Contains the dartos muscle (smooth muscle) and cremaster muscle (skeletal muscle), which regulate testicular temperature.
• Function:
  • Maintains an optimal temperature (2–3°C below body temperature) for spermatogenesis.

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2. Internal Male Reproductive Organs

a. Testes (Testicles)

• Structure:
  • Oval-shaped glands enclosed by the tunica albuginea (fibrous capsule).
  • Divided into lobules containing:
    • Seminiferous Tubules: Site of sperm production (spermatogenesis).
    • Interstitial Cells (Leydig Cells): Produce testosterone.
• Function:
  • Produce sperm and secrete testosterone.

b. Epididymis

• Structure:
  • A tightly coiled tube located on the posterior side of each testis.
  • Divided into three regions: head, body, and tail.
• Function:
  • Stores and matures sperm.

c. Vas Deferens (Ductus Deferens)

• Structure:
  • A muscular tube extending from the epididymis to the ejaculatory duct.
• Function:
  • Transports mature sperm during ejaculation.

d. Ejaculatory Ducts

• Structure:
  • Formed by the union of the vas deferens and the duct from the seminal vesicles.
  • Opens into the urethra.
• Function:
  • Mixes sperm with seminal fluid and transports it to the urethra.

e. Urethra

• Structure:
  • A tube that runs from the bladder through the penis.
  • Divided into:
    1. Prostatic Urethra: Passes through the prostate.
    2. Membranous Urethra: Short segment passing through the pelvic floor.
    3. Spongy Urethra: Runs through the corpus spongiosum and exits at the glans.
• Function:
  • Transports semen and urine to the external environment.

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3. Accessory Glands

a. Seminal Vesicles

• Structure:
  • Paired glands located posterior to the bladder.
• Function:
  • Produce seminal fluid, which contains fructose to nourish sperm and substances to enhance sperm motility.

b. Prostate Gland

• Structure:
  • Walnut-shaped gland located inferior to the bladder, surrounding the prostatic urethra.
• Function:
  • Secretes a slightly acidic fluid that activates sperm.

c. Bulbourethral Glands (Cowper’s Glands)

• Structure:
  • Pea-sized glands located below the prostate.
• Function:
  • Produce a mucus-like secretion that lubricates the urethra and neutralizes acidity.

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Summary Table: Male Reproductive Organs

Organ	Location	Function
Penis	External	Copulation and urination.
Scrotum	External	Regulates temperature for spermatogenesis.
Testes	Inside scrotum	Produce sperm and testosterone.
Epididymis	Behind testes	Matures and stores sperm.
Vas Deferens	Pelvic cavity	Transports sperm during ejaculation.
Ejaculatory Ducts	Prostate area	Mix sperm with seminal fluid.
Urethra	Penis	Passage for semen and urine.
Seminal Vesicles	Posterior to bladder	Produce seminal fluid for sperm nourishment.
Prostate Gland	Below bladder	Secretes fluid to activate sperm.
Bulbourethral Glands	Below prostate	Lubricates and neutralizes the urethra.

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Diagrammatic Representation

A labeled diagram typically shows:

• External organs: Penis, scrotum.
• Internal organs: Testes, epididymis, vas deferens, seminal vesicles, prostate, bulbourethral glands, and urethra.

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• Structure of female reproductive organs

Structure of Female Reproductive Organs

The female reproductive system is designed for ovulation, fertilization, gestation, childbirth, and hormonal regulation. It includes external organs (genitalia) and internal organs, each with specific roles.

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1. External Female Reproductive Organs

a. Vulva

• Components:
  1. Mons Pubis:
     • Fatty tissue covered by skin and pubic hair, located over the pubic bone.
  2. Labia Majora:
     • Large, outer folds of skin enclosing and protecting the other external organs.
  3. Labia Minora:
     • Smaller, inner folds of skin surrounding the vaginal and urethral openings.
  4. Clitoris:
     • A small, erectile structure highly sensitive to stimulation.
  5. Vestibule:
     • The area between the labia minora containing:
       • Vaginal opening: Entrance to the vagina.
       • Urethral opening: Passage for urine.
       • Bartholin’s Glands: Secrete mucus for lubrication.
• Function:
  • Protects internal genitalia and facilitates sexual arousal and lubrication.

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2. Internal Female Reproductive Organs

a. Ovaries

• Structure:
  • Paired, oval-shaped organs located on either side of the uterus.
  • Enclosed by a thin capsule (tunica albuginea) and contain follicles at various stages of development.
• Function:
  • Produce ova (eggs) through oogenesis.
  • Secrete hormones like estrogen and progesterone.

b. Fallopian Tubes (Oviducts)

• Structure:
  • Muscular tubes (~10–12 cm long) connecting the ovaries to the uterus.
  • Regions:
    1. Fimbriae: Finger-like projections near the ovary that capture the ovum.
    2. Infundibulum: Funnel-shaped portion near the ovary.
    3. Ampulla: Widest part, where fertilization typically occurs.
    4. Isthmus: Narrow section connecting to the uterus.
• Function:
  • Transport the ovum from the ovary to the uterus.
  • Serve as the site for fertilization.

c. Uterus

• Structure:
  • Hollow, muscular, pear-shaped organ located in the pelvis.
  • Divisions:
    1. Fundus: Rounded upper portion.
    2. Body: Central part.
    3. Cervix: Narrow, lower portion opening into the vagina.
  • Wall Layers:
    • Perimetrium: Outer connective tissue layer.
    • Myometrium: Thick, muscular middle layer.
    • Endometrium: Inner mucosal layer that undergoes cyclic changes (menstrual cycle).
• Function:
  • Supports and nourishes a fertilized egg during pregnancy.
  • Contracts during childbirth to deliver the baby.

d. Vagina

• Structure:
  • A fibromuscular canal (~7–10 cm long) extending from the cervix to the vaginal opening.
  • Lined with a mucous membrane that facilitates stretching and lubrication.
• Function:
  • Receives sperm during intercourse.
  • Serves as the birth canal during delivery.
  • Acts as the exit for menstrual flow.

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3. Accessory Structures

a. Mammary Glands (Breasts)

• Structure:
  • Composed of glandular tissue, adipose tissue, and connective tissue.
  • Contains lobes divided into smaller lobules, which contain milk-producing alveoli.
  • Milk is transported through lactiferous ducts to the nipple.
• Function:
  • Produce and secrete milk (lactation) to nourish the newborn.

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Summary Table: Female Reproductive Organs

Organ	Location	Function
Ovaries	Pelvic cavity	Produce ova and secrete sex hormones.
Fallopian Tubes	Between ovaries and uterus	Transport ova; site of fertilization.
Uterus	Pelvic cavity	Supports embryo/fetus during pregnancy.
Cervix	Lower part of the uterus	Allows menstrual flow and directs sperm into the uterus.
Vagina	Extends from cervix to vulva	Passage for intercourse, childbirth, and menstruation.
Mammary Glands	Chest (over pectoral muscles)	Produce milk for breastfeeding.
Labia and Clitoris	External genitalia	Protection, sexual arousal, and lubrication.

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Clinical Relevance

1. Disorders of the Ovaries:
   • Polycystic Ovary Syndrome (PCOS): Hormonal imbalance affecting ovulation.
   • Ovarian Cysts: Fluid-filled sacs on the ovaries.
2. Fallopian Tube Disorders:
   • Ectopic Pregnancy: Fertilized egg implants in the tube instead of the uterus.
3. Uterine Conditions:
   • Endometriosis: Growth of endometrial tissue outside the uterus.
   • Fibroids: Benign tumors in the myometrium.
4. Cervical Conditions:
   • Cervical Cancer: Linked to HPV infection.
5. Vaginal Disorders:
   • Vaginitis: Inflammation or infection of the vagina.

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• Structure of breast

Structure of the Breast

The breast (mammary gland) is a specialized structure in females designed for lactation, the process of producing and secreting milk. It is located on the anterior thoracic wall overlying the pectoralis major muscle and is composed of glandular, connective, and fatty tissues.

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Anatomical Structure of the Breast

1. External Features

1. Nipple:
   • A conical or cylindrical projection located at the center of the breast.
   • Contains openings of lactiferous ducts, which deliver milk to the exterior.
   • Surrounded by smooth muscle fibers that contract during suckling.
2. Areola:
   • Circular pigmented area surrounding the nipple.
   • Contains sebaceous glands (Montgomery glands), which secrete an oily substance to lubricate the nipple and prevent cracking during breastfeeding.

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2. Internal Structure

1. Glandular Tissue:
   • Functional part of the breast, responsible for milk production.
   • Composed of lobes (15–20 per breast), which are arranged radially around the nipple.
   • Each lobe contains smaller lobules, which consist of milk-producing units called alveoli.
2. Lactiferous Ducts:
   • Milk from alveoli is transported through small ducts that merge to form lactiferous ducts.
   • These ducts open at the nipple.
3. Lactiferous Sinuses:
   • Enlarged portions of the lactiferous ducts near the nipple that act as milk reservoirs.

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3. Connective and Fatty Tissue

1. Cooper’s Ligaments (Suspensory Ligaments):
   • Bands of connective tissue that provide structural support by anchoring the breast to the underlying chest wall.
   • Maintain the shape and position of the breast.
2. Fat Tissue:
   • Surrounds the glandular tissue and determines the size and shape of the breast.
   • Does not play a direct role in milk production.

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4. Blood Supply

• Arterial Supply:
  • Mainly from the internal thoracic artery, lateral thoracic artery, and thoracoacromial artery.
• Venous Drainage:
  • Veins form a network that drains into the axillary vein and internal thoracic vein.

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5. Lymphatic System

• Lymphatic drainage is crucial for immune defense and is clinically important in the spread of breast cancer.
• Major lymph nodes:
  • Axillary Lymph Nodes: Main drainage site.
  • Internal Mammary Nodes: Located along the internal thoracic artery.
  • Supraclavicular Nodes: Secondary drainage.

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6. Nerve Supply

• Innervated by the intercostal nerves (T4–T6), which provide sensory and autonomic input.

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Histology of the Breast

1. Alveoli:
   • Functional units where milk is produced.
   • Lined by cuboidal epithelial cells surrounded by myoepithelial cells (contractile cells that help expel milk).
2. Ducts:
   • Lined by a double layer of epithelial cells:
     • Inner luminal epithelial cells.
     • Outer myoepithelial cells.
3. Connective Tissue:
   • Surrounds the ducts and alveoli, providing structural integrity.

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Functional Aspects of the Breast

1. Milk Production (Lactation):
   • Stimulated by prolactin from the anterior pituitary.
   • Alveoli produce milk, which is stored in the lactiferous sinuses.
2. Milk Ejection:
   • Stimulated by oxytocin from the posterior pituitary during suckling.
   • Myoepithelial cells contract to expel milk through the ducts.

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Clinical Relevance

1. Breast Cancer:
   • Common malignancy in women.
   • Often spreads through the lymphatic system, particularly the axillary nodes.
   • Regular self-examination and mammography are essential for early detection.
2. Mastitis:
   • Inflammation of the breast, often associated with breastfeeding.
3. Gynecomastia:
   • Enlargement of male breast tissue, often due to hormonal imbalances.
4. Fibrocystic Breast Disease:
   • Benign condition characterized by lumps and cysts in the breast.

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Summary Table: Structure of the Breast

Component	Location	Function
Nipple	Center of the breast	Delivers milk through lactiferous ducts.
Areola	Surrounding the nipple	Lubricates the nipple (Montgomery glands).
Lobes and Lobules	Within the glandular tissue	Produce milk in alveoli.
Lactiferous Ducts	Connect lobules to the nipple	Transport milk.
Lactiferous Sinuses	Just below the nipple	Milk reservoirs.
Cooper’s Ligaments	Throughout the breast	Provide structural support.
Fat Tissue	Around glandular tissue	Determines breast size and shape.
Blood Vessels	Supplied by thoracic and axillary arteries	Provide nutrients and oxygen.
Lymph Nodes	Axillary, internal mammary, supraclavicular	Drain lymph; important in cancer spread.

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