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Understanding Testicular and Apoptotic Activity in Testicular Regression in

Understanding Testicular and Apoptotic Activity in Testicular Regression in American Crows ( Corvus brachyrhnchos ). By Luwanda k Jenkins. Photoperiod. Photoperiod. Hypothalamus. Hypothalamus. GnRH. GnRH. Pituitary. Pituitary. FSH LH. FSH LH. Testis. Testosterone.

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Understanding Testicular and Apoptotic Activity in Testicular Regression in

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  1. Understanding Testicular and Apoptotic Activity in Testicular Regression in American Crows (Corvus brachyrhnchos) By Luwanda k Jenkins CSULB

  2. Photoperiod Photoperiod Hypothalamus Hypothalamus GnRH GnRH Pituitary Pituitary FSH LH FSH LH Testis Testosterone Testosterone Testis Testis Reproduction in American Crows - Testis function is controlled through the HPG axis - Seasonal breeders - The transition from breeding to non-breeding season is markedby a reduction in testicular activity CSULB

  3. - Breeding season is characterized by an increase in testes mass, seminiferous tubules, and spermatogenesis - Non-breeding season is characterized by testicular regression and ultimately testicular function How does testicular regression occur? CSULB

  4. Apoptosis - Stimulated by extracellular and intracellular signals - Characteristics . cell shrinkage . nuclei breakdown . DNA fragments . membrane asymmetry lost . phagocytosed Necrosis - Cell swells and burst - Inflammatory response CSULB

  5. Hypothesis: - American crows experience low levels of apoptosis as the breeding season begins and high levels of apoptosis during the non-breeding season, which eventually tapers off to a basal level. CSULB

  6. - Both Sertoli (to a lesser extent) and germ cells will be dying. - Fas/FasL and Caspase 3 will both be present. CSULB

  7. Methods: -Animals: a) Adult and juvenile male American Crows (n = 60) b) OCVCD and Predator Management - Tissue processing Morphology Immunohistochemistry TUNEL Analysis - Statistical Analysis CSULB

  8. Testis Mass Appears to Increase During the Start of Breeding season CSULB

  9. Expected Results: - Decrease in testis mass and mean tubule diameter in post-breeding season crows CSULB

  10. - Increase in TUNEL labeling in post-breeding season crows - Both Sertoli and germ cells stain TUNEL positive CSULB

  11. Conclusion • Testicular regression is caused by an increase in • apoptosis • Both Sertoli and Germ cells (spermatogonia and • spermatocytes) undergo apoptosis - FasL and Caspase 3 is localized to Sertoli cells - Fas protein and Caspase 3 is localized to germ cells CSULB

  12. Significance • Little is know about American crow testicular physiology - American crow population is on a steady incline • American crows have a high susceptibility to the • WNV Goal: develop an avian contraceptive CSULB

  13. Acknowledgements: - Howard Hughes Medical Institute - Dr. Kelly Young (Research Mentor) - Mr. Wally Ross (Predator Management) - Dr. Robert Cummings (OCVCD) - Coventry Dougherty and Chantelle Moffat-Blue (lab partners) - Dr. Zed Mason (Instructor) CSULB

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