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Sex Determination

Sex Determination. in Mammals. Importance?. Does it has any economic role in livestock farming system? Cattle Poultry Fish Wildlife (may be). A Sequential Process. Chromosomal Sex Gonadal Sex Phenotypic Sex. Chromosomal Sex at Fertilization. Female ovum always carries - X X

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Sex Determination

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  1. Sex Determination in Mammals

  2. Importance? • Does it has any economic role in livestock farming system? • Cattle • Poultry • Fish • Wildlife (may be)

  3. A Sequential Process • Chromosomal Sex • Gonadal Sex • Phenotypic Sex

  4. Chromosomal Sex at Fertilization • Female ovum always carries - X X • Male sperm has either – X X or X Y • Y is the smallest human chromosome • Genes are involved in Gonadal differentiation SRY; Sex-determining region Y TDF; Testis determining Factor

  5. Gonadal Sex at 4th Week of Gestation • Mesoderm of urogenital ridge ---- most of the Gonadal cells • Ectodermal cells ------- primordial germ cells (gonocytes) • At 5th week Gonad has • Germ cells • Supporting cells • Stromal or interstitial Cells

  6. Embryo is Bipotential • Until 6th week could develop in male or female phenotype • Default development is female • Embryonic castration develop female • Female urogenital develop in the absence of gonads • Sertoli cells secretes • Mullerian Inhibiting hormone or Anti-Mul.Hormone • Testosterone triggers the development of external and internal genitalia

  7. Comparable Development of Genital Systems

  8. Steroidogenesis • Cholesterol • Pregnelone • Androsteneediol • Testosterone • Estradiol

  9. What is the chromosomal sex of freemartin calves? • Which factor make(s) makes a calf freemartin • Why there is the location of testis and ovary, while they have same embryonic origin?

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