MD210 male reproduction .ppt

Gametogenesis, Fertilisation, Implantation And Embryo Development Thick Connective Tissue Capsule ◦ Incomplete Septa  Lobules-250  1-4 Seminiferous Tubules  Loose Connective Tissue,Vessels  Interstitial Cells of Leydig  Gametogenic ◦ Production of Mature Spermatozoa  Spermatogenesis, Spermio...

Gametogenesis, Fertilisation, Implantation And Embryo Development Thick Connective Tissue Capsule ◦ Incomplete Septa  Lobules-250  1-4 Seminiferous Tubules  Loose Connective Tissue,Vessels  Interstitial Cells of Leydig  Gametogenic ◦ Production of Mature Spermatozoa  Spermatogenesis, Spermiogenesis  Spermiation  Seminiferous Tubules  Endocrine ◦ Mainly - Testosterone  Leydig Cells Testes Spermatogenesis Spermiogenesis: Spermatid to Spermatozoa Spermiogenesis Golgi Phase a. Prominent Golgi comple b. Acrosomal granules c. Centioles Spermiation • process by which mature spermatids are released from Sertoli cells into the seminiferous tubule lumen prior to their passage to the epididymis Spermatogenesis • 64 days From Spermatogonia to Spermatozoa • Different Stages of Differentiation in Each ST • Spermatozoa may be present in some tubules and predominantly spermatids or primary spermatocytes in others • Temperature • Normal sperm production requires a temperature 2-3°C below core body temperature Spermatozoa • Head – Acrosome – Nucleus • Midpiece – Centrioles – Mitochondria • Tail: Flagellum – Microtubules Figure 26-10: Sperm structure Parts of Sperm - Functions • Nucleus – Haploid - • Condensed DNA Stabilized by S-S Bonds till Fertilisation • Inactive no Synthetic Activity Occurs • Acrosome – Enzymes Facilitate Sperm Penetration • Plasma Membrane – Very little Cytoplasm in Sperm – Surrounds the Entire Tail Parts of Sperm - Functions • Mid Piece – Mitochondrial Helix – Energy for Motility - ATP Production • Flagellum – Microtubular Arrangement to facilitate sperm movement – Contractile proteins -  and  Tubulin Sertoli Cells • Nourishment of Seminiferous Tubule Cells – Inner Tubule - Avascular • Transport Nutrients to Lumen Region • Phagocytosis – Cytoplasmic Droplets from Spermatids – Damaged Germ Cells • Add To Seminal Fluid – Synthesize Luminal Proteins • Maintain Tubular Fluid Sertoli Cells - Hormonal Functions • Anti Mullerian hormone • Androgen Binding Protein – Maintains Testosterone Levels in ST • Inhibin – Inhibits FSH • Activin – Stimulates FSH • Modulate Spermatogenesis Via FSH • Convert Androgens to Estrogens – Hormonal Modulation of Tubular Function Blood-Testes Barrier Prevents Autoimmune Destruction of Sperm Produce FAS Ligand Binds to the T-Cell FAS Receptor Triggering Apoptosis of T lymphocytes Prevents Immune Attack Barrier to Blood Toxins Immuno Privilage Sertoli Cells Leydig Cells • Synthesise Androgens • Androgens Testosterone Dihydrotestosterone Dehydroepiandrosterone Sertoli cell Male Sex Steroid Synthesis Androgen Activity •  Spermatogenesis •  Bone Matrix,  Calcium Deposition • Promotes Epiphyseal Closure •  Muscle Mass,  Larynx Size •  BMR,  RBC Density,  Oxygen Utilization •  Skin Thickness,  Melanin Deposition,  Sebum Secretion Ligand specific Androgen Activity • In utero – Testosterone – internal ductal system – descent of testes • Cryptorchidism :testes do not descend into the scrotum • In utero DHT – stimulates development of external genitalia • Development of male sexual characteristics Regulation of Spermatogenesis