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Animal Science 434 Reproductive Physiology
Embryogenesis of the Pituitary and Sexual Development: Part A
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Development of the Pituitary Gland
Infundibulum Brain Rathke’s Pouch Stomodeum
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Germ Cell Migration Migration begins by the 4 week of gestation in cow and human.
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Migration from endoderm
through mesoderm.
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In birds the migration is via the blood stream.
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Fetal Kidneys Pronephros Mesonephros Metenephros regresses
portions of reproductive tract Metenephros Adult kindney and urinary ducts
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Development of Mesenephros and Metenephros
Lecture - Other Files – Early Dev Animation
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Paramesonephric Ducts
Jost Experiments Mesonephric Ducts (Wolffian Ducts) Paramesonephric Ducts (Mullerian Ducts) Testis Ovary Epididymis Oviduct Epididymis Vas Deferens Seminal Vesicles Uterus
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Sex Determination: The Jost Paradigm
Chromosomal Sex Gonadal Sex Phenotypic Sex
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Sex Determination: The Jost Paradigm
Chromosomal Sex Gonadal Sex Phenotypic Sex Chromosomal Sex Gonadal Sex Phenotypic Sex Hormonal Sex Brain and/or Behavioral Sex
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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
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Chromosomal Sex A. Drosophila
Sex depends on the number of X chromosomes X or XY or XO = Male XX or XXX or XXY = Female
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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
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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.
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Human X and Y Chromosomes
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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
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B. Other genes on the Y chromosome
The Y Chromosome Cont. B. Other genes on the Y chromosome Spermatogenesis androgen production long bone growth
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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
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Gonadal Sex
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Testis Determining Factor
XY Male Testis Determining Factor (SRY gene product) Testes develop
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Testicular Development
Mesonephric Duct (Wolffian Duct) Mesonephric Tubules Rete Tubules Mullerian Duct Tunica Albuginea Undifferentiated Sex Chords
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Mesonephric Tubules Wolffian Duct Tunica Albuginea
Rete Tubules Wolffian Duct Primary, Epithelial or Medullary Sex Chords Primordial germ cells (gonocytes) Pre-Sertoli Cells Mullerian Duct Tunica Albuginea
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Primary Sex Chords in Fetal Testis
Pre-Sertoli Gonocyte
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Hormonal Sex
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Testis Determining Factor
XY Male Testis Determining Factor (SRY gene product) Testes develop Sertoli cells secrete anti-mullerian hormone (AMH) AMH causes leydig cells to differentiate Testosterone Development of male duct system
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Wolffian Duct Cells Nucleus T Testis T TR
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Efferent Ducts Seminiferous Tubules Vas Deferens Tunica Albuginea
(Vas Efferentia) Rete Tubules Epididymis Seminiferous Tubules Vas Deferens Tunica Albuginea
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Testis Determining Factor
XY Male Testis Determining Factor (SRY gene product) 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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Vas efferentia
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Testes Determining Factor
Female Development No TDF Testes Determining Factor XX Female Ovaries Develop No Testosterone No AMH Mullerian ducts become the oviducts, uterus, cervix and part of the vagina Wolffian Ducts Regress
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Ovarian Development Regressing Tubules Mullerian Duct Primary or
Epithelial Sex Chords Future Ovarian Cortex Wolffian Duct
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Regressing Tubules Mullerian Duct Regressing Epithelial Sex Chords Future Ovarian Cortex Regressing Wolffian Duct
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Secondary or Cortical Sex Chords
Regressing Tubules Primordial Follicles Mullerian Duct Regressing Epithelial Sex Chords Future Ovarian Cortex Regressing Wolffian Duct Secondary or Cortical Sex Chords (egg nests)
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Primordial Follicles Mullerian Duct Ovarian Medulla Ovarian Cortex Regressing Wolffian Duct
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2nd Sex Chords in Fetal Ovary
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Development of the Uterus, Cervix and Vagina
Mullerian Duct
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Fused Mullerian Duct Hymen
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Broad Ligament Development (transverse anterior section)
Reproductive tract develops outside the peritoneum! Broad Ligament Development (transverse anterior section) Ovary Regressing Wolffian Duct Mullerian Duct
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Ovary Regressing Wolffian Duct Mullerian Duct
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(Posterior Transverse Section) (Future Broad Ligament)
Genital Fold (Future Broad Ligament) Regressing Wolffian Duct Mullerian Duct
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XX Female XY Male No TDF Ovaries Develop No No AMH Testosterone
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
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Phenotypic Sex
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XY Male Testis Determining Factor (SRY gene product) 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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XY Male Testis Determining Factor (SRY gene product) Testes develop
Sertoli cells secrete anti-mullerian hormone (AMH) AMH causes leydig cells to differentiate Degeneration of Mullerian Duct Testosterone Dihydrotestosterone Development of penis scrotum and accessory sex glands Development of male duct system
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Wolffian Duct Cells Nucleus T Testis T TR
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Accessory Sex Glands* and External Genitalia Cells
Nucleus T Testis T D DR 5- Reductase *Prostate, Cowper’s Gland
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