ANSC 2400: Chapter 7,8,9
32 Cards in this Set
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Follicular phase =
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Proestrus + estrus
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Luteal phase =
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Metestrus + diestrus
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Proestrus =
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Formation of ovulatory follicles + estrogen secretion Proestrus begins with the appearance of a blood-tinged vaginal discharge and by vaginal swelling. It ends when the bitch accepts the male for mating. The ovaries contain large follicles at the onset of proestrus. Estradiol gradually in…
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Estrus =
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Sexual receptivity + peak estrogen secretion Shortly after peak estradiol, behavioral estrus begins. Both LH and FSH peak in early estrus. Ovulation is completed at about third day of estrus and fertilization is completed at about the sixth day. Progesterone increases during the latter pa…
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Metestrus =
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CL formation + beginning of progesterone secretion transition from estrogen dominance to progesterone dominance
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Diestrus =
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Sustained literal secretion of progesterone Period of maximum literal function Both pregnant and open birches are considered to be in diestrus. Pregnancy status dies not alter the length of diestrus. Progesterone peaks at about 15 days then decreases gradually. Botches that donor become p…
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Anestrus =
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A period of reproductive quiescence. This long Anestrus period is responsible for a cyclic profile of three cycles on two years in dogs.
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What are the major phases of the follicular phase?
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1. elevated gonadotropin secretion from the anterior lobe of the pituitary
2. follicular growth and preparation for ovulation
3. sexual receptivity
4. ovulation
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What is the dominant hormone of the follicular phase? What is it secreted by?
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Estradiol secreted by developing follicles.
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What is the effect of estradiol?
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Estradiol causes
- profound changes that prepare the reproductive tract for copulation
- controls onset of preovulatory LH surge that causes ovulation
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What is ovulation?
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A cascade of physiological and biochemical changes that culminate in rupture of preovulatory follicles and release of oocyte from the ovary.
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What is luteolysis?
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causes CL to become nonfunctional -> less progesterone secretion by CL
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What controls GnRH release?
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Tonic and surge centers in the hypothalamus.
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What does the surge center respond to?
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Surge center responds to high blood concentrations of estradiol.
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An increase of GnRH pulse frequency causes...
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- FSH and LH to be secreted from anterior lobe of pituitary
- then: stimulation of ovarian follicles to secrete estradiol
- then: + feedback on neurons of hypothalamic surge center occurs and GnRH neurons secrete burst of GnRH
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What will cause a negative feedback on FSH secretion from the anterior lobe of the pituitary?
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Follicles that secrete inhibin later in the follicular phase.
Estradiol suppresses FSH secretion by anterior lobe.
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What controls GnRH secretion from the tonic center?
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Appears to be spontaneous but is influenced by progesterone
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What controls GnRH secretion from the surge center?
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Controlled by high estradiol accompanied by low progesterone.
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What is the activity of FSH during proestrus?
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FSH surges to recruit the provulatory wave, then drops and remains low until it surges again with LH prior to ovulation.
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What is the activity of hormones in estrus?
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Recruited follicles that have developed dominance secrete estradiol and inhibin that suppresses FSH secretion from the anterior lobe of the pituitary. FSH does not surge with same magnitude as LH. When estradiol reaches a threshold concentration, the preovulatory surge of LH occurs, induc…
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When does the first follicular wave occur?
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Either when progesterone is rising or during peak progesterone secretion.
These follicles become atretic.
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When does the second follicular wave occur?
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Initiated before luteolysis and results in a dominant follicle that will ovulate. Only follicles in growing phase when luteolysis occur will become be able to ovulate.
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What are hormone levels in follicular recruitment?
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High FSH
Low LH pulse frequency
No Inhibin
Low E2
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What are hormone levels in follicular selection?
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Low FSH
Moderate LH
Low Inhibin
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What are hormone levels in follicular dominance?
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Low FSH
High LH pulse frequency
High Inhibin
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Define atresia
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the degeneration of primordial follicles
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Emerging or recruited follicles and early selected follicles are ____ dependent. Larger selected follicles and dominant follicles are predominantly ____ dependent.
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FSH; LH
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Follicles with high numbers of LH receptros become...
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preovulatory follicles
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Major effects of estradiol on reproductive tract:
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- increased blood flow
- genital sweating
- change in tissue electrical conductivity
- leukocytosis
- increased mucosal secretion
- initiation of uterine gland growth
- elevated myometrial tone
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How is testosterone converted to estradiol?
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Cells of theca interna contain receptros for Lh. Thecal cells produce testosterone that diffuses intro granulosal cells that contain FSH receptors. Binding of FSH to granulosal cell receptros causes synthesis of enzymes that convert testosterone to estradiol.
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Ovulation is brought about by:
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- elevated blood flow
- breakdown of connective tissue
-ovarian contractions
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Explain the pathway for induced ovulation
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Neurons in preovulatory center fire, causing large quantities of GnRH to be secreted that stimulate LH surge.
1. copulation stimulates sensory nerves in the vagina and cervix.
2. impulses are relayed to spinal cord.
3. impulses are relayed to surge center in hypothalamus.
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ANSC 2400: Prelim 2