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Animal Science 434

Animal Science 434. Lecture 13: Epididymis, Ejaculation and Semen. Head. Sperm Structure. Acrosome. Neck. Middle Piece. Annulus. Principal Piece. End Piece. Sperm From Different Species. Sperm Head. (Equatorial Segment). Nucleus. Nucleus. Acrosome. Plasma Membrane. Nucleus.

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Animal Science 434

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  1. Animal Science 434 Lecture 13: Epididymis, Ejaculation and Semen

  2. Head Sperm Structure Acrosome Neck Middle Piece Annulus Principal Piece End Piece

  3. Sperm From Different Species

  4. Sperm Head (Equatorial Segment) Nucleus Nucleus

  5. Acrosome Plasma Membrane Nucleus

  6. Acrosin • Hyaluronidase Acrosome Nucleus Plasma Membrane

  7. Posterior head Capitulum Laminated columns(flexibility) Mitochondrial helix (energy) Middle piece Axoneme (9 + 9 + 2) Course outer fibers

  8. Annulus Midpiece Principal Piece Fibrous Sheath or helix

  9. Axoneme Principal Piece Middle Piece

  10. Axoneme

  11. Microtubule Sliding in Sperm Tail

  12. Sperm Metabolism Hexokinase Glucose Glucose-6-phosphate Phosphohexoisomerase Anerobic Metabolism (Glycolysis) Fructose-6-phosphate Fructose Hexokinase Lactate + 2 ATP + 2 H2O Fatty Acids Aerobic Metabolism Tricarboxcylic Acid Cycle 36 ATP/Glucose 36 ATP/Fructose

  13. Sperm Metabolism phosphatase Hexokinase Glucose Glucose-6-phosphate Phosphohexoisomerase Anerobic Metabolism (Glycolysis) Fructose-6-phosphate Fructose Hexokinase Lactate + 2 ATP + 2 H2O Fatty Acids Aerobic Metabolism Tricarboxcylic Acid Cycle 36 ATP/Glucose 36 ATP/Fructose

  14. ATP Utilization in Sperm • motility (60%) • substrate cycling (40%) • wasted • maintenance of ionic gradients • very small amount • transcription and translation • none after condensation of nucleus and loss of residual body

  15. Sperm Metabolism • Temperature dependent • ATP production increases as temperature increases • ATP dependent processes are temperature dependent • motility increases with increasing temperature

  16. Effect of Temperature on Motility Velocity (µm/s) Temperature (C)

  17. Transport of Sperm Vas Efferentia • fluid flow • cilia Caput • contractions Vas Deferens Rete Testis • contractions • fluid flow • RT secretion Corpus • contractions Seminiferous Tubule • bulk fluid flow • contractions ofof myoid cells Cauda • contractions

  18. Epididymal Function • Maturation • change in fertility • develop motility • nuclear condensation • cytoplasmic droplet • Concentration • remove water

  19. Epididymal Function • Secretion • T DHT • energy substrates (GPC, free fatty acids, carnitine) • glycoproteins, lipids, enzymes • Transport • smooth muscle contraction • Storage • cauda

  20. Hormonal Control of Epididymis • Caput • tubal testosterone • Corpus • tubal dihydrotestosterone (DHT) • vascular testosterone • Cauda • tubal DHT • vascular testosterone • Absolute need for Androgen

  21. Erection Sensory Psychic Sympathetic relaxation of penile retractor muscle Parasympathetic contraction of ischiocavernosus muscle dilation of vessels Inhibit vasoconstriction engorgement of corpus cavernosum decreased venous outflow

  22. Emission and Ejaculation Sensory Psychic Parasympathetic Sympathetic smooth muscle contraction of prostate, seminal vesicles, vas deferens, cauda epididymis, closure of the sphincter to the bladder striated muscle contraction of ischiocavernosus, bulbospongiosus, pelvic urethral emission ejaculation

  23. Ejaculate Characteristics Species Time lapse for Composition of Bull 1 second single fraction Ram 1 second single fraction Boar 5 - 25 minutes fractionated sperm-free sperm-rich coagulum Stallion 30 - 60 seconds fractionated sperm-free sperm-rich mucus Human 10 - 30 seconds single fraction but coagulated

  24. Components of Semen • water • sperm • substrates • fructose • sorbitol • inositol • glycerol phosphatidyl choline (GPC) • citric acid • inorganic salts • sodium, potassium, calcium, magnesium, chloride • proteins

  25. Initial Semen Evaluation • color • volume • concentration • motility • viability • morphology

  26. Ejaculate Characteristics Species Ejaculate Sperm Total Sperm % % Volume Conc. (x109) Motile Normal (x109/ml) /Ejaculate Bull 8.0 1.5 12 75 95 Ram 1.0 3.0 3 95 95 Boar 200 .25 50 70 90 Stallion 80 .15 12 70 40-90 Man 2-6 .15 .9 65 30-70

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