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Brain or Behavioral Sex

Brain or Behavioral Sex. Brain and Behavioral Sex Differentiation. Genetics. Gonadal Steroid Hormones. Sexual Behavior. Brain Structure. Experience. Brain Sexual Differentiation. Rat female Give testosterone shortly after birth fail to copulate or cycle like female as adult

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Brain or Behavioral Sex

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  1. Brain or Behavioral Sex

  2. Brain and Behavioral Sex Differentiation Genetics Gonadal Steroid Hormones Sexual Behavior Brain Structure Experience

  3. Brain Sexual Differentiation • Rat female • Give testosterone shortly after birth • fail to copulate or cycle like female as adult • Sexually dimorphic nucleus • Human male and female differences in behaviors • aggression • childhood play • 3D visual rotation

  4. Descent of the Testis into the Scrotum

  5. Testicular Descent Fusion of the tunica albuginea and peritoneum to form the visceral tunica vaginalis

  6. Spermatic Artery Front View Fusion of Peritoneum and Gubernaculum Testis Gubernaculum Peritoneum Inguinal Ring

  7. Rapid growth of gubernaculum Spermatic Artery Peritoneum Visceral Growth Visceral Growth Inguinal Ring Testis Peritoneum Gubernaculum (rapid growth) Parietal Tunica Vaginalis Testis is pulled down to the inguinal ring. Visceral Tunica Vaginalis

  8. Gubernaculum regresses Testis pulled into scrotum

  9. Continued regression of Gubernaculum Testis pulled deeper into Scrotum Vaginal Process attaches to Scrotum Space between Visceral and Parietal T.V. is continuous with Peritoneum

  10. Failure or Problems With Testicular Descent • Cryptorchid - highly heritable • Unilateral or bilateral • Germ cells fail to multiply and then die, sertoli cells only in seminferous tubules • High percentage develop testicular cancer • Surgical correction possible but does not reduce cancer risk

  11. Normal Dog Seminiferous Tubule

  12. Cryptorchid Dog Seminiferous Tubule SertoliCells

  13. Failure or Problems With Testicular Descent • Inguinal Hernia • Cryptorchid - highly heritable • Unilateral or bilateral • Germ cells fail to multiply and then die, sertoli cells only in seminferous tubules • High percentage develop testicular cancer • Surgical correction possible but does not reduce cancer risk

  14. Inguinal Hernia Loop of Intestine

  15. Abnormalities in Development

  16. The Freemartin in Cattle • Female born twin to a bull • Placenta membranes of the 2 fetuses fuse • Common blood supply • At time of testis formation • Before ovarian formation • Both fetuses share a common hormone milieu • testosterone • anti-mullerian hormone • Animals are chimeric (WBC from other twin) • TDF (SRY) expressed in both individuals

  17. Normal

  18. Freemartin

  19. Normal Vs. Freemartin

  20. Freemartin • AMH from bull - blocks Mullerian ducts • Posterior vagina, no anterior vagina • Testosterone from bull • clitoral enlargment • Brain changes like that of male • Ovaries do not grow but are chimeric • Ovotestis • SRY and therefore AMH and Testosterone • Further changes and adult male behavior • Use as estrus detector • Abnormalities exist as a continuum

  21. Testicular Feminization in an XY Individual • No androgen receptor • Testis • No testosterone response so no Wolffian duct development • AMH present so mullerian ducts regress • External genitalia is female due to lack of androgen

  22. Testicular Feminization

  23. 5 Reductase Deficiency in an XY Individual • Guevedoces (penis at 12) • Testis • AMH present so Mullerian ducts regress • Wolffian ducts • psuedovagina and female external genitalia • at puberty may differentiate into more of a phenotypic male

  24. Guevedoces Development Normal tissue dependent upon testosterone is shown in black.

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