Chapter 1: Male Reproductive System
The testes are housed in the scrotum to maintain spermatogenesis at approximately 35°C (2–3°C below core body temperature). Each testis has ~250 lobules, each containing 1–3 seminiferous tubules where spermatogenesis occurs. Sertoli cells inside the tubules nourish developing sperm. Leydig cells in interstitial spaces secrete testosterone (stimulated by LH). Accessory glands — seminal vesicles (fructose, 60% of semen), prostate (alkaline, 30%), and bulbourethral glands (lubrication) — collectively form seminal plasma.
Chapter 2: Spermatogenesis
From spermatogonium (2n), a defined pathway of mitosis and two meiotic divisions produces four haploid spermatozoa per spermatogonium in approximately 64 days. The final step, spermiogenesis, is morphological transformation (no division): spermatid → spermatozoon with head (acrosome + nucleus), middle piece (mitochondria spiral), and tail (flagellum).
Chapter 3: Female Reproductive System
The ovaries produce oocytes and hormones. The fallopian tube's key regions are the fimbriae (oocyte collection), ampulla (fertilization), and isthmus (uterine connection). The uterus has three layers: perimetrium (outer), myometrium (contractile), and endometrium (implantation site that cycles monthly).
Chapter 4: Oogenesis
Oogenesis begins prenatally — oogonia divide mitotically and enter meiosis I (becoming primary oocytes, arrested at prophase I). ~2 million primary oocytes at birth; ~60,000–80,000 by puberty. Each cycle, one primary oocyte completes meiosis I → secondary oocyte (n, arrested at metaphase II) → ovulated. Meiosis II completes only upon sperm entry. Total yield: 1 ovum + 2–3 polar bodies per primary oocyte.
Chapter 5: Menstrual Cycle
A 28-day cycle regulated by the hypothalamus-pituitary-ovarian axis. Four phases: menstrual (days 1–5, endometrium shed), follicular/proliferative (days 6–13, FSH → estrogen → endometrium rebuilds), ovulatory (day 14, LH surge triggers follicle rupture), and luteal/secretory (days 15–28, corpus luteum → progesterone → secretory endometrium). No pregnancy → corpus luteum degenerates → progesterone drops → menstruation.
Chapter 6: Fertilization and Early Development
Fertilization in the ampulla: acrosomal reaction (enzyme release, zona penetration), sperm-egg fusion, cortical reaction (polyspermy block), meiosis II completion, pronuclei fusion → zygote. Cleavage: morula (16 cells) → blastocyst (trophoblast + ICM + blastocoel). Implantation in endometrium day 6–7 post-fertilization. Trophoblast secretes hCG → maintains corpus luteum → no menstruation.
Chapter 7: Pregnancy, Parturition, and Lactation
Pregnancy: ~266 days. Placenta: nutrition, gas exchange, waste removal, hormone secretion (hCG, hPL, , ). Luteal-placental shift (~weeks 8–10). Parturition: oxytocin (posterior pituitary) + positive feedback loop (contractions → more oxytocin → stronger contractions → delivery). Lactation: prolactin (anterior pituitary) synthesizes milk; oxytocin (posterior pituitary) ejects milk.