Key Points Summary — 5-Bullet Rapid Revision — Summary

Spermatogenesis: spermatogonium (2n) → 4 spermatozoa (n) in ~64 days; Sertoli cells nourish (inside tubules); Leydig cells secrete testosterone (interstitial spaces).
Oogenesis arrests: Primary oocyte = prophase I (birth); Secondary oocyte = metaphase II (ovulation); Meiosis II completes only at fertilization (1 ovum + 2–3 polar bodies).
Menstrual cycle trigger: LH surge (~day 14) = ovulation; corpus luteum → progesterone = secretory endometrium; no pregnancy → progesterone falls → menstruation.
Fertilization → implantation: Ampulla (fertilization) → morula → blastocyst (trophoblast = placenta + hCG; ICM = embryo) → endometrium implantation (day 6–7); hCG maintains corpus luteum.
Parturition and lactation: Oxytocin (posterior pituitary) drives contractions via positive feedback; Prolactin (anterior pituitary) = milk synthesis; Oxytocin = milk ejection.