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CPNR 2002-2008 |
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| Home >> Early Pregnancy and Placental Function |
Early Pregnancy and Placental Function
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Successful pregnancy depends
on the complex interaction of maternal tissues and the developing
conceptus. Thus the study of differentiation and disease in
female reproductive tissues from conception through pregnancy
to birth is of equal importance as is the investigation of
the developing zygote, embryo and fetus.
The endometrium, lining the uterus and comprising epithelial and stromal cells,
undergoes dramatic differentiation changes of gene expression and morphology
through the cycle. In women, following menstruation there is approximately a
10 day phase of active stromal and epithelial proliferation (proliferative phase)
predominantly under estradiol regulation. Ovulation then occurs, to be followed
by the formation in the ovary of a progesterone-producing corpus leuteum. Under
progesterone influence the endometrium stops proliferating and differentiates
into a thick, actively secretory and well vascularized tissue (secretory or luteal
phase). If pregnancy does not occur, there is a stop in progesterone production
and the endometrium is sloughed off at menstruation. During this very dynamic
process of endometrial proliferation and differentiation, the uterus is receptive
to a blastocyst for maximally 6 days (implantation window) in the early secretory
phase.
This implantation window reflects precise changes in the differentiation status
of both epithelial and stromal cells, which interact with each other in a paracrine
fashion, and correlates with an increase in circulating progesterone concentration.
The stromal cells play a major role in this, undergoing a switch in gene expression
and morphology in the process known as decidualization. |
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