The XXXX placenta; a source and target of steroid hormones: observations during the second half of gestation.

@entity172 @entity308 @entity19517 @entity1420 @entity1815 @entity22940 @entity230 @entity291
Apart from @entity19517 ( @entity22940 ) the @entity291 placenta produces @entity1420 (P4), though the corpus luteum is the major source of P4 responsible for maintaining pregnancy. So far the biological function of placental @entity230 in @entity291 is largely unknown. However, since the local availability of free @entity1815 (E1) in the placenta seems to be controlled by sulfatase and sulfotranferase, the hypothesis was developed that placental @entity172 and P4 might act as local regulatory factors. To test for such a function placentomes from 150, 220, 240, 270 days (D) pregnant and parturient @entity291 were screened immunohistochemically for @entity1420 and @entity172 receptors (PR, ER). PR were found at all stages in the caruncle in stromal cells and capillary pericytes but only at parturition in arterial walls. Percentage of PR-positive caruncular stromal cells (CSC) increased (P<0.05) from 51.8+/-2.6% at D150 to 58.9+/-1.8% at parturition. ER were detected in CSC, caruncular epithelial (CE) cells and in caruncular capillary pericytes. Mean percentage of ER-positive CSC decreased from 39.0+/-5.9% in pregnant @entity291 to 17.5+/-8.3% at parturition (P<0.05). In CE all cells exhibited positive signals with the exception of those immediately surrounding large primary chorionic villi. Proliferation was assessed immunohistochemically by determining the percentage of Ki67-antigen positive cells. Highest values (P<0.001) were obtained for CE (58.0-68.3%), followed by the trophoblast (23.3-25.4%), CSC (10.6-45.3%) and the stroma of the chorionic villi (2.9-10.5%). A transient @entity308 of proliferation in CSC between D150-270 (P<0.05) paralleled local @entity172 tissue concentrations. The results suggest that placental @entity172 and P4 are important factors controlling caruncular growth, differentiation and function.
