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OVARIAN AND UTERINE CYCLES

OVARIAN AND UTERINE CYCLES. Dr. Saeed Vohra . Female Reproductive Cycles. Starts at puberty Normally continues throughout the reproductive years

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OVARIAN AND UTERINE CYCLES

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  1. OVARIAN AND UTERINE CYCLES Dr. Saeed Vohra

  2. Female Reproductive Cycles • Starts at puberty • Normally continues throughout the reproductive years • Monthly female sexual/reproductive cycle involves activities of hypothalamus, pituitary gland, ovaries, uterus, uterine tubes, vagina and mammary glands

  3. Female Reproductive Cycles The two “cycles” of the female • The “ovarian” cycle = (changes in ovary) • The “uterine” cycle = (changes in the mucosa of the uterus)

  4. 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

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

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

  7. OVARIAN CYCLE • FSH and LH produce cyclic changes in ovaries. • They cause • Development of follicles • Ovulation • Formation of corpus luteum Beginning at puberty (11-14 years) & ending at the “menopause” (40-45 yrs), the rhythmic cyclic changes which from the OVARIAN CYCLE.

  8. Follicular Development The development of the ovarian follicle is characterized by • Growth and differentiation of primary oocyte • Proliferation of follicular cells • Formation of Zona Pellucida • Development of the Theca Folliculi

  9. 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

  10. 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

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

  12. 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

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

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

  15. 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

  16. 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

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

  18. Corpus Luteum • It secretes Progesterone and little estrogen • These hormones prepare endometrium for implantation of Fertilized Ovum (Blastocyst) • If the oocyte is fertilized the CL enlarges & remains active for first 20 weeks of pregnancy • If the oocyte is not fertilized the CL degenerates in 10-12 days

  19. 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

  20. 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

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

  22. 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

  23. 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

  24. 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

  25. 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

  26. 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

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

  28. 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

  29. 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

  30. 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

  31. 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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