Apoptotic and proliferative activities in first trimester placentae

Apoptosis and cell proliferation are widely recognized to be important physiological processes which together maintain tissue homeostasis. The apoptotic and proliferative processes in 38 first trimester placentae were quantified using terminal deoxynucleotidyl transferase mediated dUTP nick end-labelling (TUNEL) and an antibody against Ki-67 antigen, respectively. In 14 cases, the estimation of apoptotic index was repeated with sections stained with haematoxylin and eosin by identifying the morphological features of apoptosis. We found that the indices obtained by either method correlated well with each other although a lower rate was obtained with the haematoxylin and eosin stained sections. Apoptosis was found in clusters mainly in syncytiotrophoblasts in association with fibrinoid deposits while proliferating activity was limited to cytotrophoblasts and stromal cells. A significant inverse correlation was observed between the proliferative index and gestational age as well as the apoptotic index. While the extent of apoptosis decreased with advanced gestational age, the correlation was not statistically significant. These findings provide a potential explanation for villous remodelling during trophoblastic invasion in early pregnancy.