14. Spermatogenesis Spermatogonia Primary spermatocyte Secondary spermatocyte Spermatids Spermatozoa Mitosis (46) 1 st meiotic division (23) 2 nd meiotic division (23) Differentiation Stages from spermatogonia to spermatids appear to be androgen independent. The maturation of spermatids to spermatozoa depends on androgens acting on the Sertoli cells in which the developing spermatozoa are embedded. FSH acts on the Sertoli cells to facilitate the last stages of spermatid maturation. Spermatozoa leaving the testicle are not fully mobile. Continue maturation and acquire motility during passage through the epididymis. Motility is further improved by relaxin (prostate?). Capacity of sperm to fertilise is further enhanced in the female genital tract. Capacitation enhances sperm adherence to the ovum.
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37. CONTROL OF TESTICULAR FUNCTION HYPOTHALAMUS ANTERIOR PITUITARY GnRH + TESTES SERTOLI CELL LEYDIG CELL TESTOSTERONE INHIBIN SPERMATOGENESIS FSH LH local - - - Rhythmic release of GnRH from the hypothalamus initiated at puberty
70. CONTROL OF FSH AND LH SECRETION DURING FOLLICULAR PHASE HYPOTHALAMUS ANTERIOR PITUITARY GRH + OVARY LOW LEVELS OF ESTROGEN INHIBIN FSH LH
71. CONTROL OF LH SURGE AT OVULATION HYPOTHALAMUS ANTERIOR PITUITARY GNRH + OVARY HIGH LEVELS OF ESTROGEN OVULATION FSH LH MATURE FOLLICLE
72. FEEDBACK CONTROL DURING LUTEAL PHASE HYPOTHALAMUS ANTERIOR PITUITARY GNRH + OVARY HIGH LEVELS OF PROGESTERONE LH CORPUS LUTEUM MODERATE LEVELS OF ESTROGEN
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Notas del editor
MIS continues to be secreted by sertoli cells to a peak in 1-2 old boys thereafter declines throughout life In girls mis is produced by granulosa cells in small folliclesin the ovaries