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Animal Science 434 Reproductive Physiology

Animal Science 434 Reproductive Physiology. Lec 5: Embryogenesis of the Pituitary and Sexual Development. Development of the Pituitary Gland. Infundibulum. Brain. Rathke’s Pouch. Stomodeum. Germ Cell Migration. Migration begins by the 4 week of gestation in cow and human.

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Animal Science 434 Reproductive Physiology

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  1. Animal Science 434Reproductive Physiology Lec 5: Embryogenesis of the Pituitary and Sexual Development

  2. Development of the Pituitary Gland Infundibulum Brain Rathke’s Pouch Stomodeum

  3. Germ Cell Migration Migration begins by the 4 week of gestation in cow and human.

  4. Migration from endoderm through mesoderm.

  5. In birds the migration is via the blood stream.

  6. Fetal Kidneys • Pronephros • regresses • Mesonephros • portions of reproductive tract • Metenephros • Adult kindney and urinary ducts

  7. Development of Mesenephros and Metenephros

  8. Development of Mesenephros and Metenephros Early Development Flash Movie http://www.ansci.wisc.edu/jjp1/as434/powerpoint/fa07/early_dev.swf Requires the free flash player which can be downloaded from: www.adobe.com

  9. Jost Experiments Mesonephric Ducts (Wolffian Ducts) Paramesonephric Ducts (Mullerian Ducts) Testis Ovary Epididymis Epididymis Oviduct Vas Deferens Seminal Vesicles Uterus

  10. Sex Determination: The Jost Paradigm Chromosomal Sex Gonadal Sex Phenotypic Sex

  11. Chromosomal Sex Gonadal Sex Phenotypic Sex Hormonal Sex Brain and/or Behavioral Sex Sex Determination: The Jost Paradigm Chromosomal Sex Gonadal Sex Phenotypic Sex

  12. Chromosomal Sex • Single Pair of sex chromosomes • mammals, some but not all vertebrates • Sex is environmentally determined • sea worms, fish, reptiles • Multiple sex chromosomes • invertebrates, insects, reptiles • Haplodiploidy • bees, spiders

  13. Chromosomal Sex • A. Drosophila • Sex depends on the number of X chromosomes • X or XY or XO = Male • XX or XXX or XXY = Female

  14. Chromosomal Sex • A. Drosophila • Sex depends on the number of X chromosomes • X or XY or XO = Male • XX or XXX or XXY = Female • B. Human (mammals) • XY or XXY or XXYY or XXXY = Male (testis) • XX or XXX = Female (ovary) • XO = Female with incomplete ovarian development • XXY or XXYY or XXXY or XXXXY = testis but impaired sperm production

  15. Chromosomal Sex • A. Drosophila • Sex depends on the number of X chromosomes • X or XY or XO = Male • XX or XXX or XXY = Female • B. Human (mammals) • XY or XXY or XXYY or XXXY = Male (testis) • XX or XXX = Female (ovary) • XO = Female with incomplete ovarian development • XXY or XXYY or XXXY or XXXXY = testis but impaired sperm production • C. Conclusion • The gene that controls testicular differentiation is on the Y chromosome in mammals.

  16. Human X and Y Chromosomes X Y

  17. The Y Chromosome A. Region coding for testicular development • Short arm of Y chromosome • H-Y Antigen • no longer believed to be involved • SRY • Codes for a DNA binding protein • acts as a transcription factor • Causes • primary sex chord (seminiferous tubule) development • Development of Sertoli Cells • Anti-Mullerian Hormone production by Sertoli Cells • absence of SRY • 2nd sex chords (egg nests) develop

  18. The Y Chromosome Cont. B. Other genes on the Y chromosome • Spermatogenesis • androgen production • long bone growth

  19. SRY and Birds • Birds • females ZW, males ZZ • W chromosome determines sex • SRY is found on the Z chromosome ! • SRY is not the only sex determining gene in animals

  20. Gonadal Sex

  21. Testis Determining Factor (SRY gene product) XY Male Testes develop

  22. Testicular Development Mesonephric Tubules Mesonephric Duct (Wolffian Duct) Rete Tubules Mullerian Duct Tunica Albuginea Undifferentiated Sex Chords

  23. Mesonephric Tubules Rete Tubules Wolffian Duct • Primary, Epithelial or • Medullary Sex Chords • Primordial germ cells (gonocytes) • Pre-Sertoli Cells Mullerian Duct Tunica Albuginea

  24. Primary Sex Chords in Fetal Testis Pre-Sertoli Gonocyte

  25. Hormonal Sex

  26. Sertoli cells secrete anti-mullerian hormone (AMH) AMH causes leydig cells to differentiate Testosterone Development of male duct system Testis Determining Factor (SRY gene product) XY Male Testes develop

  27. Wolffian Duct Cells Nucleus T Testis T TR

  28. Rete Tubules Efferent Ducts (Vas Efferentia) Epididymis Seminiferous Tubules Vas Deferens Tunica Albuginea

  29. Sertoli cells secrete anti-mullerian hormone (AMH) AMH causes leydig cells to differentiate Degeneration of Mullerian duct Testosterone Development of male duct system Testis Determining Factor (SRY gene product) XY Male Testes develop

  30. Vas efferentia

  31. Ovaries Develop Wolffian Ducts Regress No AMH No Testosterone Mullerian ducts become the oviducts, uterus, cervix and part of the vagina Female Development No TDF Testes Determining Factor XX Female

  32. Ovarian Development Regressing Tubules Mullerian Duct Primary or Epithelial Sex Chords Future Ovarian Cortex Wolffian Duct

  33. Regressing Tubules Mullerian Duct Regressing Epithelial Sex Chords Future Ovarian Cortex Regressing Wolffian Duct

  34. Regressing Tubules Primordial Follicles Mullerian Duct Regressing Epithelial Sex Chords Future Ovarian Cortex Regressing Wolffian Duct Secondary or Cortical Sex Chords (egg nests)

  35. Primordial Follicles Mullerian Duct Ovarian Medulla Ovarian Cortex Regressing Wolffian Duct

  36. 2nd Sex Chords in Fetal Ovary

  37. Development of the Uterus, Cervix and Vagina Mullerian Duct

  38. Fused Mullerian Duct Hymen

  39. Reproductive tract develops outside the peritoneum! Broad Ligament Development (transverse anterior section) Ovary Regressing Wolffian Duct Mullerian Duct

  40. Ovary Regressing Wolffian Duct Mullerian Duct

  41. (Posterior Transverse Section) Genital Fold (Future Broad Ligament) Regressing Wolffian Duct Mullerian Duct

  42. Testis Determining Factor (SRY gene product) No TDF XX Female XY Male Testes develop Ovaries Develop No Testosterone No AMH Sertoli cells secrete anti-mullerian hormone (AMH) AMH causes leydig cells to differentiate Degeneration of Mullerian duct Degeneration of Wolffian duct Mullerian ducts become the oviducts, uterus, cervix and part of the vagina Testosterone Development of male duct system

  43. Phenotypic Sex

  44. Testis Determining Factor (SRY gene product) XY Male Testes develop Sertoli cells secrete anti-mullerian hormone (AMH) AMH causes leydig cells to differentiate Degeneration of Mullerian Duct Testosterone Development of male duct system

  45. Dihydrotestosterone Development of penis scrotum and accessory sex glands Testis Determining Factor (SRY gene product) XY Male Testes develop Sertoli cells secrete anti-mullerian hormone (AMH) AMH causes leydig cells to differentiate Degeneration of Mullerian Duct Testosterone Development of male duct system

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