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Lecture 12: Spermatogenesis
Animal Science 434 Lecture 12: Spermatogenesis
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Spermiation
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Temporal Relationships of Spermatogenesis
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Spermatogenesis 57 days Stallion
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Multiple Generations of Germ Cells
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Bull Spermatogenesis
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Stages Specific cellular associations within a small segment of a seminiferous tubule stages are not the same length in time
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Bull Spermatogenesis - Stages
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Stages Specific cellular associations within a small segment of a seminiferous tubule stages are not the same length in time
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Bull Spermatogenesis - Stages
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Cycle progression through sequence of all stages
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Bull Spermatogenesis - Cycles
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Cycle progression through sequence of all stages
4.7 cycles to form spermatozoa some species variation
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Duration of Spermatogenesis
Bull Ram Boar Stallion Man cycle (days) Spermatogenesis
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Coordination of Stages Form Waves
some portion of seminiferous tubule is always releasing sperm
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Compartmentalization of Spermatogenesis and the Blood Testis Barrier
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Seminiferous Tubule and Interstitial Tissue
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Interstitial Tissue Vascular System Provides Nutrients Oxygen
Blood Vessel Vascular System Provides Nutrients Oxygen Growth Factors Hormones
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Blood Vessel
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Compartments Tight Junctions Myoid Cells Luminal Adluminal Basal
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Cycles and Stages
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Compartmentalization
Basal mitosis spermatogonia (A, I, B) primary spermatocytes Adluminal meiosis secondary spermatocytes spermatids spermiogenesis Lumen spermiation
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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 !!!!!
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Capacity for Sperm Production
Species Testis Sperm/gm DSP Weight (gm) (X 106) (X 109) Dairy Bull Beef Bull Ram Boar Stallion Man
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Duration of Spermatogenesis
Bull Ram Boar Stallion Man cycle (days) Spermatogenesis
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Spermatogonial Renewal in the Primate
Ap Spermatogonial Renewal in the Primate Ad Stem Cell Pool FSH B P
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Capacity for Sperm Production
Species Testis Sperm/gm DSP Weight (gm) (X 106) (X 109) Dairy Bull Beef Bull Ram Boar Stallion Man
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Variation in Sperm Production
Testis Size Efficiency of spermatogenesis mitotic division degeneration of germ cells Length of spermatogenesis
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Apoptosis of Germ Cells
Season Disease Trauma or heat Hormone levels Normal part of spermatogenesis
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Over Population of Spermatogonia
Tight Junction Sertoli Sertoli SG SG SG SG SG SG SG SG SG Basement Membrane Normal Apoptosis Inhibited PS SG Basement Membrane Sertoli AP SG Basement Membrane Sertoli
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Animation of Spermatogenesis
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