Term
| What is the major hormone produced during the luteal phase? What causes this? |
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Definition
P4
-granuosa/theca cells luteinize forming the Corpus Luteum
-CL becomes LH dependent after 6 days as theca cells become predominant, which differentiate to form large luteal cells
-large luteal cells formed lack LH receptors at first, produce large amounts of P4 |
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Term
| What is the role of PGF2-alpha in the luteal phase? |
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Definition
it is luteolytic
-luteal cells acquire surface receptors for PGF2-alpha 5-6 days after ovulation, |
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Term
| What are the 3 phases of the endometrium cycle? |
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Definition
Proliferation Phase (during follicular phase)
-estradiol stimulates growth of stratum functionalis
Secretory Phase (during luteal phase)
-progesterone stimulates development of uterine gland
Menstrual Phase
-ovarian steroids decrease inducing necrosis of stratum functionalis |
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Term
| What happens during the proliferative phase of the endometrium cycle? |
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Definition
-estradiol levels stimulate an increase in the number of glandular epithelial cells
-system of spiral arteries develops in the functionale layer of the endometrium |
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Term
| What happens during the secretory phase of the endometrium cycle? |
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Definition
-spiral arteries extend to the epithelial layer
-glandular epithelium becomes loaded with glycogen
-thickness of the functionale layer increases |
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Term
| What happens during the menstrual phase of the endometrium cycle? |
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Definition
-functionale layer regresses, shrinks & atrophies
-spiral arteries supercoil
-reduced blood flow = toxic & vasoactive substances released
-creates a physiological endometrial infarction |
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Term
| What hormones are produced by the follicles and are involved in the menstrual phase |
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Definition
-estradiol released during follicular phase
-binding to ER-alpha receptors in endometrium initiates mitosis
-progesterone during the luteal phase inhibits mitosis, stimulates mucus secretion, prevents contraction |
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Term
| What hormones are produced by the uterus and are involved in the menstrual phase |
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Definition
prostaglandins (PGF2-alpha)
-constricts uterine arterioles, causing anoxia and sloughing of the endometrium |
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Term
| What prostaglandins are involved with the endometrium cycle? What do they do? |
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Definition
PGF2-alpha & PGE2
-induce vasoconstriction in spiral arteries
-induce contraction of the myometrium |
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Term
| Describe the effect of PGF2-alpha on the corpus luteum |
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Definition
-PGF2-alpha is released in spikes as you approach the time for destruction of the corpus luteum
-after at least 3 substantial pulses released, luteolysis will be underway
-blood flow to CL is reduced
-binds to receptors to stimulate release of oxytocin & inhibit conversion of cholesterol to prognenolone
-collateral loss of small cells
-cellular degneration |
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Term
| What role does oxytocin play in regulating luteolysis |
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Definition
-released in pulses from the posterior pituitary
-drives the pulsatile release of PGF2-alpha, as well as contraction of the uterus |
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Term
| When do the large luteal cells express PGF2-alpha receptors? |
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Definition
| day 6 of the endometrium cycle |
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Term
| What type of receptors do large luteal cells express? Small cells? |
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Definition
Large: PGF2-alpha receptors
Small: LH receptors |
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Term
| Describe the status of the corpus luteum in term of PGF2-alpha & LH dependency |
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Definition
When CL is LH Independent:
-PGF2-alpha insenstive, no receptors
When CL is LH Dependent:
-PGF2-alpha senstive, receptors present |
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Term
| What is unique about the sow in terms of follicular development, uterus structure etc |
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Definition
-ovaries contain many large follicles prior to ovulation
-multiple corpora lutea
-long uterus = challenge for spermatozoa transport
-ejaculate deposited in uterus
-extended period of estrus (don't service too early)
-profound lactational anestrus
-PGF2-alpha receptors not expressed by corpora lutea until day 13 |
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Term
| What limits litter size in gilts? |
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Definition
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Term
| What does PGE2 do to COX? PGF2-alpha? |
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Definition
stimulates cyclooxgenase production
PGF2-alpha inhibits it |
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