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What are the steps of Oogenisis?
- 1) Oogonia divide by mitosis to make other oogonia and primary oocytes. All oocytes a woman has are produced during the 4th month of prenatal life. Primary oocytes begin firstmeiotic divide but stop at PROPHASE 1 and chill, keeping its 46 chromosomes.
- 2)Oocyte finishes dividing just before ovulation creating a secondary oocyte with 23 chromosome and dumping a polar body with the other 23.
- 3) Secondary oocyte begins second meiotic divide but stops at metaphase II
- 4) IF FERTILIZED: cell unites with sperm cell and another oocyte and polar body are formed.
- 5) Fertilization complete when oocyte and sperm join nuclei creating zygote.
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What are the steps of maturation of follicle and oocyte?
- 1) Primoridal follicle has primary oocyte with single layer of squamous granulosa
- 2) Primordial becomes primary follicle as grandulosa cells grow
- 3)Primary follical enlarges and granulosa cells start to form multiple layers while a "zona pellucia" forms
- 4) SECONDARY follicle: occures when vesicles develope and a well formed theca forms outside the granulosa cells
- 5.) MATURE FOLLICLE: when vescicles merge and creatue one large antrum full of fluid. Just before ovulation the cell creations one meiotic divide and ditches a polar body
- 6.)During ovulation the secondary oocyte pops out of follicle. The left over granulosa divide and become a corpus luteum
- 7) IF FERTILIZED: the corpus lutem stays around and creates hormones (progesterone) during pregnancy
- 8) IF NOT FERTILIZED: corpus luteum becomes the corpus albicans which is scar tissue.
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Short answer: explain the stages of menstrual cycle and what is happening in pituitary, ovary and endometrium in each stage:
MENSTRUAL PHASE:
- Pituitary: secretes FSH which...
- Ovary: Developes folicles, some of which may be used now or later, but first...
- Endometrium: estrogen and progesteron decrease from last cycle causes breakdown; lining sheds.
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Short answer: explain the stages of menstrual cycle and what is happening in pituitary, ovary and endometrium in each stage:
PROLIFERATIVE/OVULATION:
- (day 5-14)
- Pituitary/Hypothalamus: GnRH increases and FSH/LH increases as well.
- Ovary: Foolicles continue to mature; Estrogen produced by maturing follicles causes......
- Endometrium: grows thicker layers to replace old cells lost; spiral arteries grow, uterine milk grows
As estrogen goes up, feedback stops more follicles from growing.
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Short answer: explain the stages of menstrual cycle and what is happening in pituitary, ovary and endometrium in each stage:
OVULATION
- (Day 14)
- Pituitary: FSH and LH levels spike and stimulate estrogen secretion
- Ovary: Final maturation of oocyte and oocyte ovulates; FSH makes more immature follicles start to grow
- Uterus: Endometrial cells continue to build up
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Short answer: explain the stages of menstrual cycle and what is happening in pituitary, ovary and endometrium in each stage:
SECRETORY
- Pituitary: estrogen and progesterone inhibit FSH and LH
- Ovary: follicle converted to corpus luteum which secrets progesterone; if fertilization does not happen, luteum turns into albicans
- Uterous: endometrial cells grow and secrete uterine milk; after prgesterone levels decline, endometrium degenerates to be shed during the next menses
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Short answer: explain how sperm cells are made (spermatogenisis)
- 1) Spermatogonia divide by mitosis. One baby cell stays a spermatogonia and goes off to make new ones, the other becomes a Type B daughter cell and becomes a PRIMARY SPERMATOCYTE with 46 chromosomes
- 2)Primary spermatocyte divices by meiosis to form two secondary spermatocytes, each with 23 chromosomes
- 3.) Secondary spermatocytes divide by meiosis again to form 4 spermatatids
- 4.) Spermatatids mature into sperm cells and go off to wreak havoc on some poor porn starlet's face.
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