Progestin vs Progesterone

[acciddropping]

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Can someone clarify if I am understanding it correctly?

Progesterone - maintains uterine lining that's been proliferated by estrogen (so it prepares for gestation)
Progestin - FA said that it inhibit proliferation (thus making endometrium less suitable for implantation of the embryo)
- Synthetic form of progesterone, Progestin, has different function than the progesterone?

Thank you in advance.

 

[ulikedaggers]

Can someone clarify if I am understanding it correctly?

Progesterone - maintains uterine lining that's been proliferated by estrogen (so it prepares for gestation)
Progestin - FA said that it inhibit proliferation (thus making endometrium less suitable for implantation of the embryo)
- Synthetic form of progesterone, Progestin, has different function than the progesterone?

Thank you in advance.

My understanding is that they have similar effects, but function "differently" because of the timing of secretion (or exogenous administration). They both inhibit endometrial proliferation, both inhibit sperm entry into the uterus, both increase vascularization (spiral artery), and both inhibit LH/FSH. Progesterone does all this to prevent multiple implantations and overgrowth of the endometrium. Progestin does all this to prevent even a single pregnancy.

In the normal cycle progesterone isn't secreted until after the endometrium has already proliferated. So even though progesterone inhibits endometrial hyperplasia, the endometrium has already proliferated to a point where it is suitable for implantation. However, if you are taking a progestin OCP you will never have proliferation of the endometrium because the estrogen surge is constantly being inhibited.

 

[Pushtothestars]

My understanding is that they have similar effects, but function "differently" because of the timing of secretion (or exogenous administration). They both inhibit endometrial proliferation, both inhibit sperm entry into the uterus, both increase vascularization (spiral artery), and both inhibit LH/FSH. Progesterone does all this to prevent multiple implantations and overgrowth of the endometrium. Progestin does all this to prevent even a single pregnancy.

In the normal cycle progesterone isn't secreted until after the endometrium has already proliferated. So even though progesterone inhibits endometrial hyperplasia, the endometrium has already proliferated to a point where it is suitable for implantation. However, if you are taking a progestin OCP you will never have proliferation of the endometrium because the estrogen surge is constantly being inhibited.

Does anyone know how increasing vascularization of the endometrium prevents pregnancy?