pit_and_sex_devel_b_13胚胎性别分化

nullAnimal Science 434 Reproductive PhysiologyAnimal Science 434 Reproductive PhysiologyEmbryogenesis of the Pituitary and Sexual Development: Part BSignificance of DHTSignificance of DHTAndrogen receptor has a higher affinity for DHT Can get effects with low levels of circulating testosterone Secondary sex characteristic tissue in the male expresses 5a-reductase External Genitalia DifferentiationExternal Genitalia DifferentiationnullnullnullTestis Determining Factor (SRY gene product)Testes developSertoli cells secrete anti-mullerian hormone (AMH)AMH causes leydig cells to differentiateDegeneration of Mullerian ductTestosteroneDevelopment of male duct systemXY MaleNo TDFOvaries DevelopNo AMHMullerian ducts become the oviducts, uterus, cervix and part of the vaginaXX FemaleNo TestosteroneDegeneration of Wolffian ductBrain or Behavioral SexBrain or Behavioral SexBrain and Behavioral Sex DifferentiationBrain and Behavioral Sex DifferentiationGonadal Steroid HormonesBrain StructureSexual BehaviorGeneticsExperienceBrain Sexual DifferentiationBrain Sexual DifferentiationRat 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 Descent of the Testis into the ScrotumDescent of the Testis into the ScrotumTesticular DescentTesticular DescentFusion of the tunica albuginea and peritoneum to form the visceral tunica vaginalisnullFront ViewSpermatic ArteryFusion of Peritoneum and GubernaculumGubernaculumInguinal RingPeritoneumTestisnullVisceral GrowthVisceral GrowthPeritoneumSpermatic ArteryGubernaculum (rapid growth)Inguinal RingPeritoneumTestisVisceral Tunica VaginalisParietal Tunica VaginalisRapid growth of gubernaculumTestis is pulled down to the inguinal ring.nullVisceral GrowthVisceral GrowthPeritoneumSpermatic ArteryGubernaculum (Regressing)Inguinal CanalPeritoneumTestisVisceral Tunica VaginalisParietal Tunica VaginalisGubernaculum regressesTestis pulled into scrotumVaginal ProcessnullContinued regression of GubernaculumTestis pulled deeper into ScrotumVaginal Process attaches to ScrotumSpace between Visceral and Parietal T.V. is continuous with PeritoneumPeritoneumSpermatic ArteryGubernaculum (Fully Regressed)Inguinal CanalPeritoneumTestisVisceral Tunica VaginalisParietal Tunica VaginalisVaginal ProcessFailure or Problems With Testicular DescentFailure or Problems With Testicular DescentCryptorchid - 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 riskNormal Dog Seminiferous TubuleNormal Dog Seminiferous TubuleCryptorchid Dog Seminiferous TubuleCryptorchid Dog Seminiferous TubuleSertoli CellsFailure or Problems With Testicular DescentFailure or Problems With Testicular DescentInguinal HerniaCryptorchid - 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 riskInguinal HerniaInguinal HerniaLoop of IntestineAbnormalities in DevelopmentAbnormalities in DevelopmentThe Freemartin in CattleThe Freemartin in CattleFemale 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 individualsNormalNormalFreemartinFreemartinNormal Vs. FreemartinNormal Vs. FreemartinFreemartin 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 continuumTesticular Feminization in an XY IndividualTesticular Feminization in an XY IndividualNo 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 androgenTesticular FeminizationTesticular Feminization5 Reductase Deficiency in an XY Individual5 Reductase Deficiency in an XY IndividualGuevedoces (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 maleGuevedoces DevelopmentGuevedoces DevelopmentNormal tissue dependent upon testosterone is shown in black.Behavior and Brain Sex (Puberty Lecture)Behavior and Brain Sex (Puberty Lecture)Freemartin T from twin causes brain to develop as male Behavior is male due to brain changes and T expression as adult - Chimera Testicular Feminization No functional androgen receptor T produced and converted to E in brain to make it male Behavior is male-like 5a Reductase Deficiency No DHT produced but T present T to E in brain and so is male Behavior is male