Histological and Immunohistochemical Findings of the Intermediate Trophoblasts in Normal Full Term and Pre-Eclamptic Placentas
SH Han, K-R Kim, SA Kim, Y Lee, JY Ro. University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea
Background: Recent studies have suggested that extravillous intermediate trophoblasts can be divided into implantation site intermediate trophoblasts (ISITs) and chorionic type intermediate trophoblasts (CTITs) according to the histological and immunohistochemical findings and their distribution. Except for a presumed role of ISITs in the implantation of embryos, function of ITs has not been clearly defined. Unlike previous observation from which the name of ITs are derived, we observed that ISITs were not confined to the implantation sites and CTITs not to the chorionic membrane in normal placentas, and the number of both subtypes were increased around the degenerating villi in pre-eclamptic placentas, prompted us to consider their possible roles for compensating degenerated trophoblasts in pre-eclamptic placentas.
Design: In order to examine the composition of ITs in various extravillous compartments of normal placentas including fetal membranes, intervillous septa, subchorionic areas, basal plates, and to examine the changes of ITs, if any, in pre-eclamptic placentas, quantitative analyses of ISITs and CTITs were peroformed using immunohistochemical stainings for p63, CD146, PLAP, hPL, and α-inhibin in 13 normal full term and 10 pre-eclamptic placentas containing infarcts.
Results: Both CTITs and ISITs were closely associated in every anatomical compartment in normal and pre-eclamptic placentas. ISITs were predominant in the intervillous septum (approximate ratio 8:1) and basal plate over CTITs (12:1), while CTITs were predominant in the subchorionic area over ISITs.(5:1) Fetal membrane show equal distribution of both subtypes, and they formed two distinct layers. In pre-eclamptic placentas, both subtypes were proliferated with increased Ki-67 proliferating rates around the degenerating villi in areas of placental infarcts, extensive fibrinoid deposit, and fibrotic villi, and they formed two distinct layers at the periphery of placental infarcts.
Conclusions: The subtypes of ITs do not have site specificity in all extravillous compartments of the placentas. Increased proliferation and formation of distinct layers around the degenerating villi/trophoblasts suggests that CTITs and ISITs have close differentiation-associated relationship, and the proliferation and differentiation might be related to the microenvironment of placenta, such as intraplacental oxygen concentration.
Category: Gynecologic & Obstetrics
Tuesday, March 23, 2010 1:00 PM
Poster Session IV # 128, Tuesday Afternoon