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Ovarian cycle and fertilization

Ovarian cycle and fertilization. 44+ X+X. oogenesis. Oogonium. 44+ X+X. Primary oocyte. 22+ X. Secondary oocyte. 22+ X. First polar body. 22+ X. 22+ X. Second polar body. ovum. revision. revision. Ovarian cycle. Sexual cycles controlled by hypothalamus. GnRH. Anterior pituitary.

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Ovarian cycle and fertilization

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  1. Ovarian cycle and fertilization

  2. 44+ X+X oogenesis Oogonium 44+ X+X Primary oocyte 22+ X Secondary oocyte 22+ X First polar body 22+ X 22+ X Second polar body ovum revision

  3. revision

  4. Ovarian cycle Sexual cycles controlled by hypothalamus GnRH Anterior pituitary Gonadotropin: FSH, LH Stimulate and control cyclic changes in ovary

  5. Ovarian cycle Beginning of ovarian cycle, 5-15 follicle start growing under the influence of FSH one reaches full maturity & discharge, others degenerate and become atretic: corpus atreticum FSH stimulates maturation of granulosa cells Granulosa and thecal cells produce estrogen

  6. Ovarian cycle estrogen Uterine endometrium enter proliferative phase Thinning of cervical mucus Stimulate pituitary gland to secrete LH At mid-cycle there is LH surge

  7. Ovarian cycle LH surge Maturation promoting factor Follicular rupture and ovulation Conversion of follicle to corpus luteum Oocyte complete meiosis I and start Meiosis II Progesterone secretion

  8. Final development of Graafian follicle Primary oocyte finishes first meiotic division FSH & LH Surface of ovary bulge locally, at apex avascular spot, STIGMA • LH→collagenase → digestion of collagen fibres surrounding follicle • LH →prostaglandin →local muscular contraction in ovarian wall Oocyte excluded, cumulus oophorus cells rearrange themselves around zona pellucida to form corona radiata • Ovulation: • oocyte with cumulus oophorus cells discharged from ovary • First meiotic division complete, second meiotic division start

  9. Corpus luteum ovulation→ granulosa & theca interna cells → polyhedral +LH → yellowish pigment, CORPUS LUTEUM → secrete progesterone → uterine mucosa → secretory phase

  10. 'messenger' to the pituitary gland providing a measure of the follicular growth LH surge follicular growth support a pregnancy

  11. Fertilization hCG from trophoblast → Degeneration of corpus luteum prevented → Corpus luteum of pregnancy Continue to secrete progesterone until end of 4th month → Trophoblast secrete adequate amount of hCG → Corpus luteum regress No fertilization Corpus luteum reaches maximum development 9 days after ovulation → Degeneration of luteal clles → shrinks → fibrotic scar → corpus albicans Fate of Corpus luteum

  12. Fertilization • Occurs in the ampullary region • Ovulation takes place at the middle of the menstrual cycle • Transient increase in the body temp • About 200 – 300 spermatozoa reach the site of fertilization

  13. Fertilization • Fertilization is a sequence of events that begins with the contact between a sperm and a secondary oocyte and ends with the fusion of the nuclei of the sperm and ovum and the intermingling of maternal and paternal chromosomes

  14. Phases of fertilization • Passage of sperm through corona radiata • Penetration of the zona pellucida by the sperm • Fusion of oocyte and sperm cell membrane • Completion of the second meiotic division of the secondary oocyte

  15. Phases of fertilization • Formation of the male pronucleus • Union of male and female pronucleus • Splitting of 23 paternal and 23 maternal chromosomes • Division of cytoplasm • Formation of two celled structure called the Zygote

  16. Results of fertilization • Restoration of diploid chromosomal number • Bi-parental inheritance • Primary sex determination • Initiation of the cleavage of the zygote

  17. Clinical orientation • In Vitro fertilization and “embryo” transfer • Surrogate mother.

  18. In vitro fertilization

  19. The An egg stripped off its cumulus cells . The spem cell is immobilized with the tip of the injection pipette Oocyte-Cumulus Complex sperm cell is released into the egg. sperm cell is further aspirated into the injection pipette The egg is held with a holding pipette. A single sperm cell has been aspirated into the injection pipette and is ready to be injected into the egg.

  20. Thank You Placed in uterus

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