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Embryology

Embryology. Introduction & Gametogenesis. INTRODUCTION. Embryology : Study of prenatal stages of development from the fertilization of the ovum to the birth of the new individual. Descriptive Embryology Comparative Embryology Experimental Embryology. Uses.

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Embryology

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  1. Embryology Introduction & Gametogenesis

  2. INTRODUCTION Embryology : Study of prenatal stages of development from the fertilization of the ovum to the birth of the new individual. • Descriptive Embryology • Comparative Embryology • Experimental Embryology

  3. Uses • Helps us understand human anatomy better • Helps us understand why some children are born with organs that are abnormal • May help us prevent or treat such abnormalities

  4. Introduction • First 9 months of every individual spent within the womb • During this period we develop from 1 cell to organism with billions of cells • 2 stages- • Embryo- first 2 months • Fetus- 3rd month to birth

  5. Subdivisions • General embryology • Systemic embryology

  6. Haeckel's Dictum "ontogeny recapitulates phylogeny”

  7. Descriptive terms of Position, Direction and Planes

  8. MITOSIS

  9. meiosis

  10. CHROMOSOME NUMBER IN SOMATIC CELLS • MAN WOMAN • 44 XY 44XX • 46 46

  11. Chromosome number • Males 44+ x y females 44+xx • If gametes have the same no. ? • 44xy+ 44xx = 88xxxy ?

  12. GAMETES • OVUM SPERM • 22 X 22X 44XX FEMALE • OVUM SPERM • 22 X 22 Y 44XY MALE

  13. EMBRYO • Male gamete+ female gamete= embryo • Sperm + ovum = zygote (embryo)

  14. Gonads & Gametes • Male gonad- Testis • Male gamete- Spermatozoa

  15. Gonads & Gametes • Female gonad- Ovary • Female gamete- Ovum

  16. Gametogenesis • Process of formation and development of specialized generative cells, called gametes or germ cells. • During this process chromosome number is halved • Diploid haploid • and cell shape is altered

  17. PRIMORDIAL GERM CELLS

  18. OOGENESIS

  19. MATURATION OF OVUM Primary Ovarian Follicle Antral Follicle Graffian follicle

  20. SECONDARY OOCYTE AT OVULATION

  21. SPERMATOGENESIS

  22. SEMINIFEROUS TUBULE SHOWING ARRANGEMENT OF SPERMATOCYTES

  23. SPERMIOGENESIS

  24. Structure of a sperm

  25. COMPARISON

  26. COMPARISON • OOGENISIS • Maturation starts as early in the 7th month of IUL • 1st & 2nd meiotic division are not continuous. • Nuclear division is equal but the cytoplasmic division is unequal. • Only one ovum formed • Life span- 24 to 48 hours. • Size of matured Ovum 135 microns. • SPERMATOGENESIS • Maturation starts during puberty, the germ cells are kept dormant. • 1st & 2nd meiotic division are continuous without arrest. • Nuclear division and the cytoplasmic division is equal. • 4 spermatids formed • Life span- 48 to 72 hours. • Length of matured sperm 45 microns.

  27. ABNORMAL GAMETES Abnormal sperms Abnormal oocytes

  28. Thank You

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