Figure 4

Immunohistochemical analysis of syncytin 2 (HERV-FRD Env) in age-matched second trimester (19 weeks) normal (upper panel) and T21-affected placentas (lower panel). Upper panel A. Immunostaining with anti-syncytin2 antibody showed positive reactivity in a fraction of elongated cytotrophoblastic cells. Scale bar = 10 μm. B. In this large magnification, syncytin 2 immunostaining was observed in the cytoplasm of cytotrophoblastic cells and in the thin cytoplasmic processes. Scale bar = 10 μm. Lower panel C. Syncytin 2 was detected in some cuboidal cytotrophoblastic cells. Scale bar = 10 μm. D. This high magnification shows the cytoplasmic localization of syncytin 2 immunostaining in several cytotrophoblastic cells. Scale bar = 10 μm.