Fig. 2.
Representative photomicrographs of immunohistochemical staining for Ki67 (an endogenous marker of cell proliferation) in maternal and fetal placenta in (A) NAT, (B) NAT-ET, (C) IVF and (D) IVA groups on d 22 of pregnancy. The blackish nuclei represent positive staining and the reddish/pinkish nuclei (nuclear fast red staining) represent unlabeled nuclei. Note nuclear staining of Ki67 in fetal membranes (FM; fetal placenta; chorioallantois) and endometrium (E, maternal placenta). In the inset in (D), note a lack of positive staining in the control sections in which mouse IgG was used in place of the primary antibody.