Morphologic alterations and immunohistochemical analysis of alpha-fetoprotein and CD34 in chorionic villi of anembryonic pregnancy.

OBJECTIVE To investigate the morphology of chorionic villi using light and electron microscopy, especially the expression of alpha-fetoprotein (AFP) in trophoblastic cells and the process of maturation and margination vasculogenesis proper using CD34 immunohistochemistry in tissues from the first trimester of pregnancy loss due to anembryonic pregnancy in comparison with embryonic pregnancy. METHODS The study consisted of 2 groups: 9 patients with anembryonic pregnancies and 9 patients with embryonic pregnancies between 6 and 10 weeks of gestational age registered at the Department of Gynecology and Obstetrics, University Hospital of Karadeniz Technical University, Turkey, from March 2003 to December 2004. We examined the chorionic villi using light and electron microscopy. For immunohistochemical staining, we used AFP and CD34. RESULTS Microscopically, pathologic changes were shown in syncytiotrophoblast cells of anembryonic pregnancies and AFP was strongly expressed by villous trophoblastic cells compared to embryonic pregnancies. We determined the CD34 positivity in both groups. In anembryonic pregnancies, vascular elements were much fewer in number compared with embryonic pregnancies (p<0.001) and were located in the formed of hemangioblastic cords. CONCLUSION Placental vasculogenesis is a basic feature in all types of pregnancy and a relationship exists between trophoblast cells and vessels in the chorionic villi with the potential to influence each other's functions. Defective chorionic villus vascularization is associated with embryonic death. This study may support the hypothesis, as suggested by previous studies, that anembryonic pregnancy results from early embryonic death and subsequent reabsorption rather than from the nondevelopment of an embryo.