Which one? Estrogen or Progesterone

[HDP]

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Alans Notes say Estrogen! So which one is it? I have found different sources that say estrogen and others that say progesterone. I put Estrogen but of course got it wrong.

Thanks




Thickening of the Endometrium

Which of the following hormones is responsible for the thickening of the endometrium?


A. Estrogen (16%)
B. Oxytocin (3%)
C. Progesterone (52%)
D. Luteinizing hormone (17%)
E. Follicle stimulating hormone (12%)
Correct Answer: C. Progesterone

Follicle stimulating hormone causes the follicle in the ovary to begin to divide to complete meiosis II. The growing follicle that will eventually release the egg during ovulation secretes estrogen. The estrogen then spurs the secretion of luteinizing hormone by the posterior pituitary gland, causing the follicle to rupture and release the egg. It is progesterone that is then secreted by the ruptured follicle called the corpus luteum. It is the progesterone that is responsible for readying the endometrium for implantation should fertilization occur.

 

[Ellabelle]

Feralis' notes say that upon implantation, the trophoplast produces HCG which maintains estrogen and progestrone production by the corpus luteum, "which in turn maintains endometrium".

 

[Ellabelle]

Also, in another section it says that estrogen AND progestrone maintain the endometrium.
But in my biology lecture, my professor says (I'm looking at my notes now) that progestrone is responsible for the thickening. So I guess even though estrogen could also have a role, progestrone is a better answer.

 

[ilovefruits]

I assume this question meant preparing/thickening of the endometrium prior to implantation? Progesterone is responsible for this, while they're both important in maintaining the pregnancy after implantation (hCG blah blah). There's a much higher level of progesterone than estrogen a couple of days after ovulation, and this is the only peak for progesterone during menstrual cycle, and is the "implantation window".

 

[HDP]

So I guess if I get the question I will mark progesterone!

 

[aznriptide859]

Pretty sure I saw a very similar question to this on my DAT.

And now I know I missed it lol.

 

[Eri3]

Estrogen levels are very high in the begging of the cycle then the progesterone levels increase - thus progesterone plays the biggest role. If you have KBB or Kaplan Review Notes, it has a really good explanation and graphs which make it easier to understand why it is progesterone.

 

[mehc012]

Estrogen levels are very high in the begging of the cycle then the progesterone levels increase - thus progesterone plays the biggest role. If you have KBB or Kaplan Review Notes, it has a really good explanation and graphs which make it easier to understand why it is progesterone.

I suppose it depends on where you 'start' the cycle...most texts I have seen begin at menstruation, which occurs during periods of low estrogen and progesterone.

These low levels, aside from causing menses, cause the hypothalamus to release GnRH
--> ant. pituitary releases LH and FSH
--> primordial follicles begin maturing into 1° follicles
--> 1° follicles release Estrogen and Inhibin (inhibits stimulation of more follicles)
--> eventually, increasing Estrogen and Inhibin levels prevent the release of more LH and FSH from the pituitary, though it is still produced.
--> When the Estrogen levels increase beyond a certain threshold, they actually stimulate the release of all that stored-up LH and FSH...this is the 'LH surge'
--> LH surge triggers ovulation
--> Corpus luteum (which remains after ovulation) produces estrogen and progesterone, but not inhibin
--> Involution of the corpus luteum causes lowered estrogen and progesterone lvls, restarting the cycle

ALTERNATIVELY, pregnancy occurs, HCH is released from the placenta, and the corpus luteum is maintained until the placenta has developed enough to produce its own estrogen and progesterone.


**Things of Note:
**They begin at the menses so that each cycle ends either with the onset of the menses or with fertilization and pregnancy.
**Estrogen has an inhibitory effect on the pituitary and hypothalamus (negative feedback on LH and FSH release) until the levels get incredibly high in the absence of progesterone...those high levels briefly have positive feedback to trigger the LH surge, but for most of the cycle, estrogen is inhibitory to further LH and FSH release


At any rate, you probably didn't mean 'beginning' literally, so now I seem like a tool, but I feel that this topic (the hormonal regulation of the female cycle) is often poorly understood, so I thought it would be helpful here anyway. Your comment pretty much hits the issue on the head: estrogen is responsible for many things prior to the thickening stage of the uterus, but thickening only happens when both estrogen AND PROGESTERONE are high, not when only estrogen is elevated. In general, I consider progesterone to be the primary hormone responsible for regulating the behavior of the endometrium - without it, the endometrium wouldn't thicken, persist, support a placenta, etc...and pregnancy would fail.