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Animal Science 434

Animal Science 434. Lecture 12: Spermatogenesis. Spermiation. Temporal Relationships of Spermatogenesis. Spermatogenesis. 57 days. Stallion. Multiple Generations of Germ Cells. Bull Spermatogenesis. Stages. Specific cellular associations within a small segment of a seminiferous tubule

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Animal Science 434

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  1. Animal Science 434 Lecture 12: Spermatogenesis

  2. Spermiation

  3. Temporal Relationships of Spermatogenesis

  4. Spermatogenesis 57 days Stallion

  5. Multiple Generations of Germ Cells

  6. Bull Spermatogenesis

  7. Stages • Specific cellular associations within a small segment of a seminiferous tubule • stages are not the same length in time

  8. Bull Spermatogenesis - Stages

  9. Stages • Specific cellular associations within a small segment of a seminiferous tubule • stages are not the same length in time

  10. Bull Spermatogenesis - Stages

  11. Cycle • progression through sequence of all stages

  12. Bull Spermatogenesis - Cycles

  13. Cycle • progression through sequence of all stages • 4.7 cycles to form spermatozoa • some species variation

  14. Bull Ram Boar Stallion Man cycle (days) 13.5 10.4 8.3 12.2 16 Spermatogenesis61 47 39 57 75 Duration of Spermatogenesis

  15. Coordination of Stages Form Waves • some portion of seminiferous tubule is always releasing sperm

  16. Compartmentalization of Spermatogenesisand theBlood Testis Barrier

  17. Seminiferous Tubule andInterstitial Tissue

  18. Blood Vessel Interstitial Tissue • Vascular System Provides • Nutrients • Oxygen • Growth Factors • Hormones

  19. Blood Vessel

  20. Compartments Myoid Cells Tight Junctions Luminal Adluminal Basal

  21. Cycles and Stages

  22. Compartmentalization • Basal • mitosis • spermatogonia (A, I, B) • primary spermatocytes • Adluminal • meiosis • primary spermatocytes • secondary spermatocytes • spermatids • spermiogenesis • Lumen • spermiation

  23. !!!!! Blood Testis Barrier • Sertoli cells and associated tight junctions • first appears at puberty • induced by FSH • after puberty can be maintained by FSH and/or testosterone • essential for meiosis

  24. Capacity for Sperm Production Species Testis Sperm/gm DSP Weight (gm) (X 106) (X 109) Dairy Bull 650 18 10 Beef Bull 500 18 8 Ram 550 26 14 Boar 750 30 25 Stallion 165 18 3 Man 40 4 .045 - .2

  25. Bull Ram Boar Stallion Man cycle (days) 13.5 10.4 8.3 12.2 16 Spermatogenesis61 47 39 57 75 Duration of Spermatogenesis

  26. FSH Ap Spermatogonial Renewal in the Primate Ad Stem Cell Pool B P

  27. Capacity for Sperm Production Species Testis Sperm/gm DSP Weight (gm) (X 106) (X 109) Dairy Bull 650 18 10 Beef Bull 500 18 8 Ram 550 26 14 Boar 750 30 25 Stallion 165 18 3 Man 40 4 .045 - .2

  28. Variation in Sperm Production • Testis Size • Efficiency of spermatogenesis • mitotic division • degeneration of germ cells • Length of spermatogenesis

  29. Apoptosis of Germ Cells • Season • Disease • Trauma or heat • Hormone levels • Normal part of spermatogenesis

  30. Normal Apoptosis Inhibited PS Sertoli Sertoli PS SG AP AP SG Sertoli Sertoli SG AP SG AP SG SG SG SG SG Basement Membrane SG SG SG SG SG Basement Membrane Over Population of Spermatogonia Tight Junction Sertoli Sertoli SG SG SG SG SG SG SG SG SG Basement Membrane

  31. Animation of Spermatogenesis Spermatogenesis

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