Uterine cells of mice produce their own estrogen during pregnancy, which is critical for maintaining the growth of blood vessels.(2009)
From the article:
The researchers discovered that during decidualization, mouse uterine stromal cells increase their expression of P450 aromatase, a key enzyme that acts with other enzymes to convert androgens to estrogen.
Even in pregnant mice that have had their ovaries removed, the production of uterine estrogen is able to support the growth and differentiation of the tissue and blood vessels needed to sustain the pregnancy.
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Progesterone supplementation is required, however, indicating that local estrogen alone is not sufficient to maintain pregnancy. Blocking the activity of the aromatase with an inhibitor also blocked decidualization, the researchers found, another indication that a successful pregnancy relies on estrogen production in uterine cells.
There are advantages to producing the appropriate amount of estrogen right where it is needed, rather than relying on the ovaries, Bagchi said.
“During pregnancy, the ovaries would need to secrete a high level of estrogen to ensure that the right amount of estrogen is present in the uterus to support decidualization,” she said. “You can imagine that if the estrogen level goes high systemically, it could have a deleterious effect on pregnancy itself by antagonizing the progesterone action.”