Endocrinology Physiological Control of Reproduction Male reproductive physiology Testes: - Sperm and majority testosterone (required from sperm to develop and mature) produced here - Spermatogenesis occurs here - occurs at a temperature lower than body temperature; the testes are outside the body Epididymis and ductus deferens: - Maturation of sperm, storage and prepared for exit into the urethra Seminal vesicles (provide secretions to keep sperm alive): - Fructose - source of energy - Prostaglandins - Bulk of seminal fluid - Clotting factors - fluids clots to hold the sperm in place so the sperm have a better chance to swim up to the egg Prostate: - Secretions alkalinises vagina and triggers clotting (so it only clots once the sperm has been delivered into the uterus) Cells of testes produce sperm Sertoli cells (develop sperm and respond to hormones FSH) Where the sperms develop from the germinal cells, need to protect them: - Blood testes barrier, which provides a tight junction that prevents anything toxic passing through, no damage to genetic material - Nourishment of developing sperm - Phagocytic - something pathogenic gets through, they will attach it or attack bad developing sperm - Secrete fluid to flush sperm into epididymis - Secrete ABP (androgen binding protein) to maintain high testosterone levels in testes by binding the androgen, testosterone (main male androgen). It is required for maturation of sperms. - SITE OF ACTION OF FSH and TESTOSTERONE Sertoli cells are grouped together in seminiferous tubules, provides lots of developing sperms Leydig Cells Also know as INTERSTITIAL cells because it is between tissues They are endocrine cells, they synthesis, sometimes store, and actively secrete the hormone testosterone. They are located within connective tissue BETWEEN seminiferous tubules.
Endocrinology Functionally distinct from site of spermatogenesis Secrete Testosterone - Steroid hormone derived from cholesterol (leydig cells take the cholesterol and convert it into testosterone - Secreted into blood, bound to plasma proteins ANDROGEN BINDING PROTEINS (ABP) Endocrine organs have a rich blood supply so the hormones can be secreted straight into the blood. Testosterone is being produced in the leydig cells - majority is caught by the ABP and fed to the sertoil cells and the rest into the blood. Testosterone actions: See textbook for details! Directed study: Consult a text book to research the physiological actions of testosterone ... Hormonal control of testicular function Work out a diagram to show the control of testicular function by the hypothalamus and the pituitary. Hormonal control of spermatogeneisis Hypothalamus releases the hormone GnRH (gonadotrophion releasing hormone) when we want to produce sperm (all the time) - released in a pulsing motion every 90mins. Pituitary LH GnRH from the hypothalamus! Gonadotrophin releasing hormove FSH Leydig Cells Gonadotrophin hormones are released from the pituitary and to the gonads Testosterone GnRH causes the pituitary to simultaneously release two hormones LH (luteinising hormone) and FSH (follicle stimulating hormone) they have identical structure to those in the woman as they have assigned affects in the woman but not in the man exactly.