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OVARIAN AND UTERINE CYCLES

OVARIAN AND UTERINE CYCLES. By: Dr. Mujahid Khan. Female Reproductive Cycles. Starts at puberty Normally continues until the reproductive years Sexual or reproductive cycle involves activities of hypothalamus, pituitary gland, ovaries, uterus, uterine tubes, vagina and mammary glands. GnRH.

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OVARIAN AND UTERINE CYCLES

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  1. OVARIAN AND UTERINE CYCLES By: Dr. Mujahid Khan

  2. Female Reproductive Cycles • Starts at puberty • Normally continues until the reproductive years • Sexual or reproductive cycle involves activities of hypothalamus, pituitary gland, ovaries, uterus, uterine tubes, vagina and mammary glands

  3. GnRH • Gonadotropin-releasing hormone (GnRH) is synthsized by neurosecretory cells in the hypothalamus • Carried to the anterior pituitary gland by hypophysial portal system • Stimulates the release of 2 hormones produced by this gland that act on ovaries

  4. FSH • Follicle-Stimulating Hormone stimulates the development of ovarian follicles • Production of Estrogen by the follicular cells

  5. LH • Luteinizing Hormone serves as the trigger for ovulation • Stimulates the follicular cells and corpus luteum to produce progesterone

  6. OVARIAN CYCLE • FSH and LH produce cyclic changes in ovaries called Ovarian Cycle • They cause development of follicles, ovulation and corpus luteum formation

  7. Follicular Development • Growth and differentiation of primary oocyte • Proliferation of follicular cells • Formation of Zona Pellucida • Development of the Theca Folliculi

  8. Theca Folliculi • Formed as the primary follicle increases in size and the adjacent connective tissue organizes into a capsule • Theca Interna: Internal, vascular and glandular • Theca Externa: A capsule like layer

  9. Antrum • Is a large fluid filled cavity appears around the follicular cells of ovarian follicle • Contains follicular fluid • Ovarian follicle now called a vesicular or secondary follicle

  10. Cumulus Oophorus • The primary oocyte is pushed aside of the follicle called Cumulus Oophorus • Here it is surrounded by a mound of follicular cells • It projects into the antrum

  11. The follicle becomes enlarge until it gets maturity • Produces swelling on the surface of the ovary • Early development of ovarian follicle is induced by FSH • Final stages of maturation require LH

  12. Estrogen • Growing follicles produce estrogen • It regulates the development and functions of reproductive organs • Vascular theca interna also produces some estrogen

  13. Ovulation • It occurs around mid cycle about 14 days in a 28 day menstrual cycle • Ovarian follicle undergoes sudden growth spurt under the influence of FSH & LH • Producing swelling or a bulge on Ovarian surface • An avascular spot appears on this swelling called Stigma

  14. Ovulation • Cumulus Oophorus detach from interior of the distended follicle • It is triggered by a surge of LH production • It usually follows the LH peak 12-24 hrs • LH Surge causes the stigma to balloon out forming a vesicle • The stigma ruptures and expel secondary oocyte with the follicular fluid

  15. Ovulation • Expulsion of oocyte results from raised intrafollicular pressure • The expelled secondary oocyte is surrounded by Zona Pellucida and layers of follicular cells called Corona Radiata • Zona Pellucida is composed of 3 glycoproteins ZPA, ZPB & ZPC

  16. Corpus Luteum • After ovulation the walls of the ovarian follicle and theca folliculi collapse and thrown into folds called Corpus Luteum

  17. Corpus Luteum • It secretes Progesterone and some estrogen • These hormones stimulate endometrial glands to secrete and prepare endometrium for implantation of fertilized Ovum (Blastocyst) • If the oocyte is fertilized the CL enlarges • If the oocyte is not fertilized the CL involutes and degenerates in 10-12 days

  18. Uterine or Menstrual Cycle • It is the period during which the oocyte matures, is ovulated and enters the uterine tube • Cyclic changes in the endometrium caused by estrogen and progesterone • These changes occur in the internal layer of the Uterus

  19. Menstrual Cycle • Average menstrual cycle is 28 days • Day 1 is the day when menstrual flow begins • It vary in length by several days in normal women • Ranges between 23 and 35 days in 90% of women

  20. Phases of Menstrual Cycle • Menstrual Phase • Proliferative Phase • Luteal Phase • Ischemic Phase

  21. Menstrual Phase • Starts with 1st day of menstrual cycle • Lasts for 4-5 days • Functional layer of uterine wall is sloughed off and discarded with the menstrual flow • Blood discharge from vagina is combined with small pieces of endometrial tissue

  22. Proliferative Phase • Is a phase of repair and proliferation • Lasts for 9 days • Coincides with growth of ovarian follicle • Controlled by estrogen secreted by follicles • 2-3 fold increase in thickness of endometrium • The glands increase in number and length and the spiral arteries elongate

  23. Luteal Phase • Is a secretory or progesterone phase • Lasting about 13 days • Coincides with formation, functioning and growth of corpus luteum • Glandular epithelium secrete glycogen rich material • Endometrium thickens under the influence of estrogen and progesterone

  24. Luteal Phase • Spiral arteries grow into the superficial layer • Arteries become increasingly coiled • Large venous network develops • Direct arterio-venous anastomoses are the prominent features

  25. If Fertilization Occurs • Fertilized ovum implants in endometrium on about 6th day of this phase • HCG hormone secreted by syncytiotrophoblast keeps the corpus luteum secreting estrogen and progesterone • The luteal phase continues and menstruation does not occur

  26. If Fertilization Doesn’t Occur • No HCG • Corpus luteum degenerates • Estrogen and progesterone levels fall • Secretory endometrium enters an ischemic phase • Menstruation occurs

  27. Ischemic Phase • Decreased levels of estrogen & progesterone • Stoppage of glandular secretion • Loss of interstitial fluid • Marked shrinking of endometrium • Spiral arteries become constricted • Venous stasis & Ischemic necrosis • Rupture of damaged vessel wall • Blood seeps into the surrounding connective tissues

  28. Ischemic Phase • Pools of blood form and break through the endometrial surface • Resulting in bleeding in uterine lumen and from the vagina • Loss of 20-80 ml of blood • Entire compact layer and most of the spongy layer of endometrium is discarded

  29. Pregnancy Phase • If pregnancy occurs, endometrium passes into the pregnancy phase • Menstruation cycle resumes 6-10 weeks after the termination of pregnancy • Menopause usually occurs between the ages of 48-55 • Termination of reproductive period causes psychic changes called Climacteric

  30. Anovulation • Some women do not ovulate • Inadequate release of gonadotropins (FSH & LH) • Ovulation can be induced by clomiphene citrate • This stimulates pituitary to secrete gonadotropins • Causes multiple ovulation • Multiple pregnancies • Spontaneous abortions

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