Sex Determination in Humans

Male Reproductive System Sperm are produced in seminiferous tubules. Leydig cells, located in interstitial tissue between seminiferous tubules (50 days), secrete testosterone (70 days). Converts indifferent structures into male external genitalia (penis and scrotum). In an adult, each testis is composed primarily of seminiferous tubules. testes descend into scrotum maintains slightly lowered temperature

Human Male Reproductive System

Male Reproductive System Production of sperm Wall of seminiferous tubule consists of germinal cells which become sperm, by meiosis, and supporting Sertoli cells (secrete products required for spermatogenesis, also engulfs the extra cytoplasm in spermatids). Each parent cell undergoes mitosis, and one of the two daughter cells then undergoes meiosis to form sperm.

Male Reproductive System Diploid daughter cell - primary spermatocyte First meiotic division produces two haploid secondary spermatocytes. Each undergoes second meiotic division to separate the chromatids and produce two haploid cells, spermatids. Total of four haploid spermatids produced by each primary spermatocyte.

Testis and Spermatogenesis

Male Reproductive System Spermatozoa Head encloses nucleus and capped by an acrosome - contains enzymes that aid in egg penetration. body and tail provide propulsion

Male Reproductive System Male accessory sex organs Epididymis (sperm not motile for 18 hrs) vas deferens seminal vesicles (fructose rich fluid, 60% sv) prostate gland (30%sv) Urethra

Male Reproductive System Male accessory sex organs erectile tissue corpora cavernosa - dorsal side corpora spongiosum - ventral side

Male Reproductive System Hormonal control of male reproduction FSH stimulates the Sertoli to facilitate sperm development. LH stimulates Leydig cells to secrete testosterone. Principle negative feedback inhibition applies to FSH and LF secretion.

Hormonal Interactions