Transcript male
Testis each is surrounded by tunica albuginea, dense collagenous connective tissue seminiferous tubules epididymus - ducts that lead to vas deferens Seminiferous tubules Sertoli cells - columnar - basal nuclei - sER - occluding junctions - basal compartment of lumen - adluminal compartment of lumen --> blood/testis barrier protect gametes from immune response The function of Sertoli Cells: Physical and nutritional support of germ cells Phagocytosis of cytoplasm eliminated during spermiogenesis Tight junctions --> blood/testis barrier Androgen-binding protein (ABP) binds testosterone Inhibin --> negative feedback of FSH Medium for nourishment and transport of spermatozoa Spermatogenic cells - spermatogonia are basal - most are primary spermatocytes - secondary spermatocytes - spermatids - spermatozoa in adluminal area Spermatogenesis spermatogonia--> primary spermatocytes Meiosis: reduction division , diploid primary spermatocytes reduce chromosome number to haploid spermatids Spermiogenesis: spermatid to spermatozoa Spermatogonia - small germ cells in basal region - primary spermatocytes in the adluminal compartment largest cells in the seminiferous tubules large nuclei - secondary spermatocytes are small cells, short lived - spermatids, small round haploid connected by cytoplasmic bridges Spermiogenesis - spermatid to spermatozoa - accumulate hydrolytic enz - remodel - flagellum forms Phases of spermiogenesis: - Golgi phase - cap phase - acrosomal phase - maturation phase Golgi phase - hydrolytic enzymes made by the RER-->Golgi apparatus --> trans Golgi comples --> pre-acrosomal granules --> fuse--> acrosomal vesicle --> binds onto nuclear envelope Centrioles start to form flagellar axoneme--> return to perinuclear area --> help form connecting piece. - Cap phase - acrosomal vesicle enlarges and partially surrounds nucleus--> acrosome Acrosomal Phase - nucleus condenses - mitochondria concentrate around the nucleus - microtubules form a cylindrical manchette--> cell elongates - at the flagellum--> annulus joins the tail’s midpiece with the principal piece - outer dense fibers around the axoneme--> surrounded by fibrous sheath Maturation phase - xs cytoplasm is released and phagocytosed by Sertoli cells --> spermiation, spermatozoa are released --> become motile (capacitated) in female repr. System Mature sperm: Head - acrosome Tail - neck - connecting piece, 9 columns encircling 2 centrioles - outer dense fibers - middle piece - outer dense fibers - annulus - principle piece - longest piece - axoneme - 7 outer dense fibers - fibrous sheath - endpiece - axoneme and plasmalemma - at the very end, individual mt