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Physiology of ovary

Physiology of ovary. By Alvin Lee. THE OVARIAN CYCLE EVENTS. A) FOLLICULAR GROWTH B) OVULATION C) CORPUS LUTEUM FORMATION D) CORPUS LUTEUM REGRESSION. Follicle Development Follicular Wave. 4. Regression. Dominance. Growth. Selection. Next Recruitment. Recruitment.

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Physiology of ovary

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  1. Physiology of ovary By Alvin Lee

  2. THE OVARIAN CYCLE EVENTS • A) FOLLICULAR GROWTH • B) OVULATION • C) CORPUS LUTEUM FORMATION • D) CORPUS LUTEUM REGRESSION

  3. Follicle DevelopmentFollicular Wave 4 Regression Dominance Growth Selection Next Recruitment Recruitment • Follicle development occurs as a wave-like pattern consisting of “Recruitment”, “Selection”, “Growth”, “Dominance”, and “Regression” phases • Usually 2 to 4 follicular waves occur during the estrous cycle in cattle

  4. Follicle DevelopmentFollicle Stimulating Hormone (FSH) 5 Regression Next Recruitment Recruitment FSH FSH • FSH precedes recruitment of follicles (causes follicles to start growing) • FSH is the same hormone used for superovulation and embryo transfer in cattle

  5. Follicle DevelopmentLuteinizing Hormone (LH) 6 Regression Dominance Growth Selection LH pulses • LH promotes further follicle growth and maturation of egg

  6. Follicle Development and OvulationLuteinizing Hormone (LH) and Estrogen 7 Ovulation Dominance Estrogen Growth Estrus Selection LH Surge • LH stimulates follicle growth and a growing follicle produces high levels of estrogen • High levels of estrogen, in turn, cause estrus and surge release of LH that triggers ovulation

  7. Follicle Development During the Estrous CycleExample for 3 Follicular Waves 8 0 2 4 6 8 10 12 14 16 18 20 0 Ovulation Ovulation Estrus Estrus Day of the Estrous Cycle • Length of the estrous cycle in cattle with 3 follicular waves is typically 20 to 24 days

  8. Follicle Development During the Estrous CycleExample for 2 Follicular Waves 9 0 2 4 6 8 10 12 14 16 18 20 0 Ovulation Ovulation Estrus Estrus Day of the Estrous Cycle • Length of the estrous cycle in cattle with 2 follicular waves is typically 18 to 20 days, slightly shorter than the estrous cycle with 3 follicular waves

  9. Endocrinology During the Estrous CycleFollicle Stimulating Hormone (FSH) 10 0 2 4 6 8 10 12 14 16 18 20 0 Ovulation Ovulation Estrus Estrus FSH Day of the Estrous Cycle • Example shown for cattle having 3 follicular waves during a 21-day estrous cycle

  10. Endocrinology During the Estrous CycleLuteinizing Hormone (LH) 11 0 2 4 6 8 10 12 14 16 18 20 0 Ovulation Ovulation LH Surge LH Surge Estrus Estrus LH pulses LH pulses Day of the Estrous Cycle • Example shown for cattle having 3 follicular waves during a 21-day estrous cycle

  11. Endocrinology During the Estrous CycleEstrogen 12 0 2 4 6 8 10 12 14 16 18 20 0 Ovulation Ovulation Estrogen Estrus Estrus Day of the Estrous Cycle • Example shown for cattle having 3 follicular waves during a 21-day estrous cycle

  12. Corpus Luteum (CL)Growth and Regression 13 0 2 4 6 8 10 12 14 16 18 20 0 Ovulation Growth Regression Estrus Estrus Day of the Estrous Cycle • Corpus luteum develops from the ovulated follicle and takes approximately 10 days to reach mature size

  13. Corpus Luteum (CL)Progesterone 14 0 2 4 6 8 10 12 14 16 18 20 0 Growth Regression Estrus Estrus Progesterone Day of the Estrous Cycle • Corpus luteum produces progesterone • Progesterone is responsible for maintenance of pregnancy after conception occurs

  14. Corpus Luteum (CL) RegressionProstaglandin F2 (PG) 15 0 2 4 6 8 10 12 14 16 18 20 0 Growth Regression Estrus Estrus PG Day of the Estrous Cycle • Late in the estrous cycle, uterus produces PG which causes regression of corpus luteum • PG is the same or similar hormone in “Lutalyse®”, “Estrumate®”, “ProstaMate®”, and “In Synch®”

  15. Corpus Luteum (CL) MaintenanceWhen cow becomes pregnant … 16 0 2 4 6 8 10 12 14 16 18 20 0 Growth Maintenance Estrus PG Embryo Day of the Estrous Cycle • Presence of embryo blocks uterus to produce PG late in the estrous cycle which causes maintenance of corpus luteum and production of progesterone for pregnancy

  16. Progesterone regulates LH PulsesLuteinizing Hormone (LH) 17 0 2 4 6 8 10 12 14 16 18 20 0 LH pulses LH pulses LH Surge Estrus Estrus Progesterone Day of the Estrous Cycle • Progesterone regulates secretion pattern of LH pulses and hence, follicular development

  17. Endocrinology of the Estrous Cycle 18 0 2 4 6 8 10 12 14 16 18 20 0 Progesterone PG Estrogen Estrus Estrus Day of the Estrous Cycle • Relationships among estrogen, progesterone, and PG during the 21-day estrous cycle

  18. Physiology and Endocrinologyof the Estrous Cycle 19 0 2 4 6 8 10 12 14 16 18 20 0 Estrus Estrus Day of the Estrous Cycle • Relationships among structural and hormonal changes during the 21-day estrous cycle (example shown for cattle having 3 follicular waves)

  19. SUMMARY OF OVARIAN CYCLE EVENTS • FOLLICULAR GROWTH • -after regression of CL, (caused by PGF2a), FSH↑ and LH↑ • ①LH stimulates secretion of androgens in the theca interna, which diffuse into granulosa cells • ②FSH stimulate: • i)conversion of androgens →oestrogen • ii)Formation of LH receptors on granulosa cells • Estrogen-rich fluid formed by granulosa cells separates the granulosa cells and forms pocket known as ANTRUM • ↑ of oestrogen causes preovulatory LH SURGE!!

  20. B) OVULATION • LH SURGE!!: • i)promotes maturation of oocytes by resuming meiosis through 1st polar body stage • ii) promotesintrafollicular production of PGA & PGE → rupture of follicle • Formation of mutivesicular bodies (MVB) as outpockets of exposed theca externa • MVB secrete proteolytic enzyme → digest ground substance cementing the theca externa fibroblast, allowing oocyte to escape (OVULATION)

  21. C) CORPUS LUTEUM FORMATION -LH SURGE causes FSH receptors number↓ in granulosa cells causing conversion of androgens →oestrogento ↓, -LH attaches to receptors in granulosa cells (currently corpus luteum) to produce progesterone -as progesterone↑, FSH ↓ and LH ↓ D) CORPUS LUTEUM REGRESSION - progesterone↓, causes FSH ↑ and LH ↑,hence cycle is repetead

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