Applied Developmental Biology The Hashemite University Dr. Lubna Tahtamouni The Hashemite University 23/2/2009 Week # 3 Spermatogenesis 1

Gametogenesis: Spermatogenesis + Oogenesis

A. Spermatogenesis

Male Reproductive System Production of: Semen Hormones

Semen 5% Sperm 2. 65% Secretions of seminal vesicles: proteins, enzymes, mucus, fructose, prostaglandins 3. 30% secretions of prostate glands: milky alkaline fluid, high in basic sugars, pH ~ 7.3-8

Testis: Groups of Seminiferous Tubules

Cross Section through Testis Cells in spermatogenesis: Spermatogenic cells Sertoli cells Leydig cells

Sertoli cells

prominent euchromatic nucleus and prominent nucleolus - cell sends processes around developing germ cells making cell margins difficult to observe at LM level inter-Sertoli cell tight junctions at the base of the tubule form blood testis barrier - synthesizes and secretes a fluid into the lumen containing: 1. androgen binding protein (ABP) that binds testosterone and creates increased (total) concentration of testosterone - secretion of ABP stimulated by FSH and testosterone 2. inhibin that suppresses FSH secretion from pituitary provides environment for germ cell development (nurse cell) phagocytose and digest shed residual bodies produced by developing germ cells

interstitial cells of Leydig (Leydig cells): - steroid-synthesizing cell with enriched sER and mitochondria - produce and secrete testosterone - stimulated by LH and prolactin from pituitary

Seminiferous Tubule

Spermatogenesis

Spermatogenesis

Spermatogenesis Spermatocytogenesis Meiosis Spermiogenesis

Spermiogenesis

The shape of a human sperm cell is adapted to its function Middle piece Neck Head Plasma membrane Tail Mitochondrion (spiral shape) Nucleus Acrosome

Cross Section through the Tail

Hormonal Regulation of Spermatogenesis

Semen Analysis – reference values Semen value Volume Concentration Motility Morphology Normal range > 2.0ml > 20 million/ml > 40% motile >14%