Final Cheat Sheet — REP-02 Must-Know Facts — Notes

The 30 Non-Negotiable Facts for NEET

#	Fact
1	Testes in scrotum: 2–3°C below body temp for spermatogenesis
2	~250 lobules per testis; 1–3 seminiferous tubules per lobule
3	Sertoli cells: INSIDE seminiferous tubules; nourish sperm
4	Leydig cells: INTERSTITIAL spaces; secrete TESTOSTERONE
5	Spermatogenesis: spermatogonium (2n) → 4 spermatozoa (n); ~64 days
6	Sperm head: acrosome (enzymes) + haploid nucleus
7	Sperm middle piece: MITOCHONDRIA spiral → ATP for motility
8	Seminal vesicles: 60% semen, FRUCTOSE energy for sperm
9	Oogenesis begins in FETAL LIFE (oogonia → primary oocytes prenatally)
10	At birth: ~2 million primary oocytes; at puberty: 60,000–80,000
11	PRIMARY oocyte arrested at PROPHASE I
12	SECONDARY oocyte arrested at METAPHASE II
13	Meiosis II completes ONLY upon SPERM PENETRATION
14	Oogenesis: 1 primary oocyte → 1 ovum + 2–3 polar bodies
15	Fallopian tube: Fimbriae → Infundibulum → Ampulla → Isthmus
16	FERTILIZATION occurs in the AMPULLA of the fallopian tube
17	Ovulation triggered by LH SURGE (~day 14); not FSH
18	Corpus luteum secretes PROGESTERONE (maintains secretory endometrium)
19	Cortical reaction = polyspermy block (zona pellucida hardens)
20	Morula = 16-cell solid ball; Blastocyst = trophoblast + ICM + blastocoel
21	TROPHOBLAST → placenta + hCG; ICM → embryo
22	IMPLANTATION in endometrium: day 6–7 post-fertilization
23	hCG: trophoblast-secreted; maintains corpus luteum; pregnancy test basis
24	Pregnancy: 266 days from fertilization (38 weeks) / 40 weeks from LMP
25	Placenta: nutrition, gas exchange, waste, hormones (hCG, hPL, $E_{2}$ , $P_{4}$ )
26	OXYTOCIN (posterior pituitary) → uterine contractions = POSITIVE FEEDBACK
27	PROLACTIN (anterior pituitary) → milk PRODUCTION
28	OXYTOCIN → milk EJECTION (let-down reflex)
29	Menstrual cycle: FSH → follicle/estrogen → LH surge → ovulation → progesterone → implantation or menstruation
30	If no pregnancy: corpus luteum degenerates → $P_{4}$ drops → MENSTRUATION