PHYL2001 Lecture Notes - Lecture 16: Sex Steroid, Sertoli Cell, Seminiferous Tubule
Document Summary
Lh acts on the leydig cells to regulate testosterone secretion. Fsh acts on the sertoli cells to enhance spermatogenesis: sertoli cells for survival of sperm, smaller amount in testicles and even less in seminiferous tubules so need fsh for survival. If mutation where sertoli cells express no fsh receptors, decreased testicular activity and increase sperm malformation. Lh receptor mutation on leydig cells, no testosterone produced, male internal and external genitalia not formed, appear as female. In males: lh and fsh secretion- constant day to day after. Pulsatile release every 2 hours from puberty to death in males. Negative feedback, to stop hormones getting too high. As fsh rises and binds to sertoli cells, produce more and more inhibin to correct amount of fsh. Testosterone negative feedback on lh producing cells and negative feedback in neurons in hypothalamus that make. Gnrh, broken down to estradiol, estradiol produces neg effect. All male and female sex hormones have conversions between them.
