Reproductive System: Male and Female Anatomy

Male Reproductive System

Testes

Feature	Description
Location	Scrotum (extr-abdominal, 37°C)
Size	4 × 3 × 2 cm
Weight	10-15 g each
Coverings	Tunica vaginalis, tunica albuginea, tunica vasculosa
Septa divide	~250 lobules (each with 1-4 seminiferous tubules)
Blood supply	Testicular arteries (from aorta), pampiniform plexus (venous)

Seminiferous tubules:

Cell	Function
Spermatogonia	Stem cells (spermatogenesis)
Sertoli cells	Support, nourishment, blood-testis barrier, inhibin, AMH
Primary/secondary spermatocytes	Meiosis
Spermatids	Spermiogenesis (maturation)

Interstitial (Leydig) cells: Testosterone production (LH-stimulated)

Epididymis

Part	Length	Function
Head (caput)	~6 cm	Sperm entry, maturation
Body (corpus)	~6 cm	Sperm transport
Tail (cauda)	~6 cm	Sperm storage

Vas Deferens (Ductus Deferens)

Feature	Description
Length	~45 cm
Course	Epididymis → spermatic cord → inguinal canal → pelvis → behind bladder
Termination	Ejaculatory duct (with seminal vesicle duct)

Spermatic Cord

Content	Structure
Vas deferens	Muscular duct
Testicular artery	From aorta
Cremasteric artery	From inferior epigastric
Artery to vas deferens	From superior vesical
Pampiniform plexus	Veins
Genital branch of genitofemoral nerve	Cremaster muscle
Sympathetic nerves	Vasomotor
Lymphatics	Paraaortic nodes

Accessory Glands

Gland	Secretion	Percentage of Semen
Seminal vesicles	Fructose, prostaglandins, fibrinogen	60-70%
Prostate	Citric acid, acid phosphatase, PSA, zinc	20-30%
Bulbourethral (Cowper)	Pre-ejaculate (lubrication)	< 5%

Penis

Part	Description
Root (crura + bulb)	Attached to perineum
Body (shaft)	3 erectile cylinders: 2 corpora cavernosa + 1 corpus spongiosum (urethra)
Glans	Distal expansion of corpus spongiosum
Prepuce (foreskin)	Retractable skin covering glans

Spermatogenesis

Stage	Duration	Location
Spermatogonia → primary spermatocyte	16 days	Basal compartment
Primary → secondary spermatocyte (meiosis I)	24 days	Adluminal compartment
Secondary → spermatid (meiosis II)	8 hours	Adluminal compartment
Spermatid → spermatozoon (spermiogenesis)	24 days	Adluminal compartment

Total duration: ~64 days (74 days including epididymal transit)

Female Reproductive System

Ovaries

Feature	Description
Location	Lateral pelvic wall (ovarian fossa)
Size	3 × 2 × 1.5 cm
Weight	5-10 g each
Ligaments	Ovarian (to uterus), suspensory (to pelvic wall, contains ovarian vessels)
Blood supply	Ovarian arteries (from aorta)

Ovarian follicles:

Stage	Description
Primordial	Oocyte + flat granulosa cells (resting)
Primary	Cuboidal granulosa cells, zona pellucida
Secondary (antral)	Fluid-filled antrum, theca interna/externa
Graafian (mature)	Pre-ovulatory, 20-25 mm
Corpus luteum	After ovulation (progesterone)
Corpus albicans	Degenerated corpus luteum (scar)

Uterine (Fallopian) Tubes

Part	Length	Function
Infundibulum	2 cm	Fimbriae (capture ovum)
Ampulla	5-8 cm	Fertilization (usual site)
Isthmus	2-3 cm	Sperm transport
Intramural (interstitial)	1 cm	Through uterine wall

Uterus

Feature	Description
Shape	Pear-shaped, thick-walled
Size	7.5 × 5 × 2.5 cm (nulliparous)
Parts	Fundus, body, cervix
Position	Anteverted, anteflexed (usually)

Uterine wall:

Layer	Description
Perimetrium (serosa)	Outer peritoneal covering
Myometrium	Smooth muscle (3 layers)
Endometrium	Inner lining (stratum functionalis + basalis)

Cervix:

• Lower portion (1/3 of uterus)
• Internal os (to uterine body) + external os (to vagina)
• Endocervical glands (mucus, varies with cycle)

Vagina

Feature	Description
Length	7-10 cm (anterior), 10-12 cm (posterior)
Fornices	Anterior, posterior, lateral (around cervix)
Epithelium	Stratified squamous (non-keratinized)
Flora	Lactobacillus (acidic pH, protects against infection)

External Genitalia (Vulva)

Structure	Description
Mons pubis	Fat pad over pubic symphysis
Labia majora	Outer folds (homologous to scrotum)
Labia minora	Inner folds
Clitoris	Erectile (crura + body + glans, homologous to penis)
Vestibule	Space between labia minora (urethral + vaginal openings)
Bartholin (greater vestibular) glands	Lubrication (homologous to bulbourethral glands)
Skene (paraurethral) glands	Female prostate homolog

Mammary Glands (Breasts)

Feature	Description
Location	Pectoralis major (2nd-6th ribs)
Structure	15-20 lobules (each with lactiferous duct)
Nipple	Smooth muscle (erectile)
Areola	Pigmented skin (Montgomery glands)
Blood supply	Internal thoracic, lateral thoracic, intercostal arteries
Lymph drainage	Axillary (75%), internal thoracic (25%)

Oogenesis and Ovarian Cycle

Stage	Timing	Events
Follicular phase	Day 1-14	FSH drives follicle growth, estrogen rises
Ovulation	Day 14	LH surge, oocyte released (24-36 hours after LH peak)
Luteal phase	Day 15-28	Corpus luteum secretes progesterone

Menstrual cycle:

• Menstruation (Day 1-5): Shedding of endometrium
• Proliferative phase (Day 6-14): Estrogen-driven endometrial growth
• Secretory phase (Day 15-28): Progesterone-driven maturation

Puberty

Feature	Female	Male
Onset	8-13 years	9-14 years
First sign	Thelarche (breast bud)	Testicular enlargement
Growth spurt	Earlier (peak ~12 years)	Later (peak ~14 years)
Menarche	12-13 years (average)	—
Spermarche	—	13-14 years (average)

Menopause

• Average age: 51-52 years
• Ovarian follicle depletion
• Decreased estrogen/progesterone
• Symptoms: Hot flashes, vaginal dryness, bone loss
• Postmenopausal: Increased risk of osteoporosis, cardiovascular disease