Okay, I have been confused about this for almost a year now. Can someone please explain to me how progesterone can maintain and thicken the endometrium during the menstrual cycle but also thin the endometrium when used as contraception? I am struggling to understand how it both promotes pregnancy and prevents pregnancy. (I know it has other effects like thickening cervical mucus, I'm specifically wondering about the endometrial lining!) Thanks in advance!
Progesterone Question
- Thread starter bbeer900
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It's been years since I thought about this but I'll take a quick stab.
Thickening:
Estrogen promotes epithelial cell proliferation whereas progesterone encourages differentiation and the secretory phase of the cycle.
Thinning:
So we know endometrial hyperplasia is caused by estrogen unopposed by progesterone. If we have excess progesterone to estrogen then we have a state where the tissue is basically told to hold tight. It doesn't grow and some apoptosis occurs.
Like I said, it's been a long time but I remember it being related to the hormonal milieu. Don't get hung up on the 1 hormone having different effects. It has different effects in different settings and concentrations. Many hormones also have different effects based on temporality and based on constant vs pulse dosing. Maybe you can use this to read more about it.
Thickening:
Estrogen promotes epithelial cell proliferation whereas progesterone encourages differentiation and the secretory phase of the cycle.
Thinning:
So we know endometrial hyperplasia is caused by estrogen unopposed by progesterone. If we have excess progesterone to estrogen then we have a state where the tissue is basically told to hold tight. It doesn't grow and some apoptosis occurs.
Like I said, it's been a long time but I remember it being related to the hormonal milieu. Don't get hung up on the 1 hormone having different effects. It has different effects in different settings and concentrations. Many hormones also have different effects based on temporality and based on constant vs pulse dosing. Maybe you can use this to read more about it.