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Functions of Ovary:
- Development of female gametes
- Synthesis and release of steroid hormones
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Ovarian Stroma Components: (Stroma has outer ovarian cortex and inner ovarian medulla:
- Intersitial cells that produce steroid hormones
- Outer Ovarian Cortex contains OOCYTES that are each enclosed in a OVARIAN FOLLICLE or tissue sac
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Ovarian Cortex:
- -Each follicle contains an OOCYTE surrounded by a follicular wall consisting of a thin MEMBRANE GRANULOSA made up of follicular cells and surrounded by THECA (connective tissue)
- -ZONA PELLUCIDA is a transparent membrane between oocyte and follicular wall
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FSH and FOLLICULAR GROWTH:
- -FSH receptors found on granulosa cells of follicle early in follicular development
- -Most follicular growth is FSH dependent
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Follicular growth and hormone secretion:
- -Steroid hormone secretions in ovary are under direct influence of two pituitary gonadotropins:
- 1.FSH
- 2.LH
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LH EFFECTS ON FOLLICULAR AND CORPUS LUTEUM GROWTH:
- -LH receptors found on early thecal cells of follicles and facilitate thecal cell development
- -Shortly before ovulation, LH receptors also appear on granulosa cells, which causes them to convert to luteal cells, which leads to:
- progesterone release, follicle and oocyte maturation, ovulation, and corpus luteum formation and maintenance
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Mitosis of granulosa cells is controlled by?
FSH
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Formation of theca controlled by:
LH
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Formation of follicular fluid controlled by:
FSH and LH
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Which Hormone Controls OOCYTE MATURATION, OVULATION, and CORPUS LUTEUM?
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OOGONIA and OOOCYTES:
- -in mitotic division in fetus
- -In meiotic division and are enclosed within follicles
- -Primary OOCYTES are arrested in prophase of first meiotic division for as long as 50 yrs
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Ovarian oogonia, Oocytes and Follicle Numbers through life:
- 8 weeks gestation: 600,000 Oogonia
- 5 months gestation: million Oogonia
- Birth: 1-2 million (primordial follicles with Oocytes)
- 1 yr: Ovaries contain some tertiary follicles
- Puberty: 200,000 follicles with oocytes
- 35 yrs: 100,000 follicles with Oocytes
- Menopause:0-few follicles
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Tertiary Follicle growth stimulated by:
- -FSH
- Stimulates estrogen production in granulosa cells of tertiary follicles via the delta 5 pathway
- Tertiary follicles produce most of the circulating estrogen in the body
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Ovarian Tertiary Follicle Steroid Hormone Synthesis:
-Delta 5 pathway in tertiary follicles (rockn during estrogen peak)
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Graafian follicle growth and hormone secretion:
-The granulosa cells in the graafian follicles develop LH receptors and transform into luteal cells which produce progesterone through the delta 4 pathway to prepare the uterus to be ready for implantation (LUTEINIZATION)
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Delta 5 Pathway?
Delta 4 Pathway?
- in Tertiary Follicles
- In pre ovulatory follicles and the corpus luteum
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Follicle maturation and ovulation:
- -20 large tertiary follicles form in each of the 2 ovaries
- -Only 1 matures to the GRAAFIAN stage to ovulate each month and the rest go through Atresia
- -Ovulation alternates between the right and left ovary each month
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the nucleus of most human cells are:
- -Diploid(2N)
- -46 Chromosomes in 23 pairs
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OOGENESIS results in the production of?
-Mature haploid (1N) female gametes
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OOCYTE MATURATION AND OVULATION:
- 1.Birth:female ovaries contain primary oocytes in primary follicles
- Arrested in first meiotic division and this condition persists in 2nd and tertiary follicles until Graafian follicle stage
- 2. Surge of LH in the middle of menstrual cycle causes completion of the 1st meiotic division (Producing a secondary haploid oocyte & 1st polar
- body).
- 3. At Graafian stage, LH secretion by pituitary occurs,LH acts on the follicle cells and triggers the resumption of meiosis in the oocyte
- When the membrane of the Oocyte disintegrates then the 1st meiotic division is completed
- 4.SECOND MEIOTIC division begins while still in graafian follicle, but completes it after ovulation when the ovum is penetrated by sperm
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2nd Meiotic Arrest:
- -Haploid secondary oocyte begins second meiotic divison and arrested while the oocyte is still in the Graafian follicle
- -The female germ cell is ovulated through the stigma of Graafian follicle as 2ndary oocyte in 2nd meiotic arrest
- -the stigma ruptures open to allow the ovum to move outside of ovary into oviduct
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Ovulation caused by:
- -LH
- involves a local degradation of the follicle wall
- -tear in follicular wall develops at the stigma and the Ovum oozes out with follicular fluid
- -After Ovulation the ovum moves to oviduct into a 2nd meiotic arrest
- -SPERM PENETRATES THE OVUM and completes the 2nd meiotic division to form a mature haploid oocyte
- -Fertilization
occurs and a diploid (2N) zygote forms
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Corpus Luteum:
- -Formed from ovullated follicle
- -Luteinizing granulosa cells form corpus luteum
- -Secretes high levels of PROGESTERONE and moderate levels of ESTROGEN under LH INFLUENCE through the DELTA 4 PATHWAY
- -Present for last 2 weeks of menstrual cycle and degenerates before menstruation
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Oviducts=Fallopian tubes:
- -Paired tubes extending from near the ovaries to the uterus
- -Internal lining of the oviducts has mucuous glands and ciliated cells that beat in the direction of the uterus
- -Smooth muscle in the middle layer of the oviduct contract to help transport the ovum toward the uterus
- -ESTROGEN: increases mucuous secretion,cilia beat faster,smooth muscle contracts frequently,transport ovum
- -PROGESTERONE: decreases mucuous secretion, decreases smooth muscle contraction
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UTERUS:
1..FUNDUS-above entrance of oviducts
2..CORPUS-body of uterus tapers down to cervix
3..CERVIX-narrow region near vagina
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UTERINE WALLS:
1.Perimetrium-external surface
2.Myometrium-middle layer with a thick layer of smooth muscle
3.Endometrium-inner layer which shows structural channges during menstrual cycle and hormonal control
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Uterine ENDOMITRIUM: (inner layer of uterine cavity)
- -Stratum functionalis: Shed during menstruation
- -Stratum basalis: not shed, contains blood vessels that contribute to menstrual flow
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VAGINAL LAYERS:
- 1.TUNICA MUCOSA: inner layer (elastic fibers allow it to stretch)
- 2.TUNICA MUSCULARIS: middle layer (rich in smooth muscle)
- 3.TUNICA ADVENTITIA: thin outer layer of elastic tissue
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VAGINA:
- -home to bacteria, fungi, and protozoa
- -acidic env. maintained by bacteria
- -inhibits yeast (fungal) growth
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VULVA (external female genitalia):
Mons Pubis,Labia majora,Labia Minora,Vaginal Introitus,Hymen,Clitoris
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Labia Majora homologous to:
Male scrotum
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LESSER VESTIBULAR GLANDS homologous to:
GREATER VESTIBULAR GLANDS homologous to:
- -Male prostate gland in males
- -they are fluid secreting glands
- -secrete mucous
- -Bulbourethral glands in males
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BREASTS:
- -glandular tissue and associated ducts embedded in fatty tissue
- -ALVEOLUS: milk is synthesized and secreted (secreted from alveoli into 2ndary mammary tubules)
- -SECONDARY TUBULES from each lobe form a mammary duct that empties into a MAMMARY AMPULLA where milk is stored.
- -AMPULLA empties into LACIFEROUS DUCT which empties into NIPPLE
- -Variation in sizr due to fat distribution
- -EACH BREAST HAS 15-20 Lobes of Glandular Tissue
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