Apoptosis in human chorionic villi and decidua in normal pregnancy, spontaneous abortion and ectopic pregnancy

Abstract

To investigate possible apoptotic changes, the cleavage of DNA in human chorionic villi and decidua was examined in normal pregnancy (NP), spontaneous abortion (SA) and ectopic pregnancy (EP). Very limited but detectable cleavage of DNA was recognized in the chorionic villi and decidua in NP. However, the degree of apoptosis was not correlated with either urinary levels of human chorionic gonadotropin and/or gestational age. A ladder pattern, characteristic of the apoptotic breakdown of DNA was identified in SA. The DNA laddering was present in the villi, but absent in the decidua in EP. Quantitative analysis of low molecular weight (mol. wt.) fragments of DNA revealed a significant increase in SA compared to that in NP. However, the levels of low mol. Wt. DNA showed a significant decrease in the decidual tissue, together with a significant increase in the villous tissue, in EP as compared to those in NP. An analysis in situ revealed cells undergoing apoptosis only in the cytotrophoblast in NP. By contrast, apoptotic cells were predominant in the syncytiotrophoblast in SA and EP. In the decidual tissue, labeled cells were occasionally seen in NP. Their numbers increased in SA but decreased in EP. The present study demonstrates that the occurrence of apoptosis differs in NP, SA and EP. These results indicate that apoptosis might play a critical role in normal embryonic development and wastage in humans.