Figure 2

Five-day OSE culture maintained in DMEM-HG medium with phenol red. a) Phase contrast microscopy of a live cell with a large oocyte phenotype (120 μm in diameter) shows a centrally located nucleus with nucleolus and perinuclear accumulation of cell organelles. b) Larger cell reaching 180 μm shows similar morphology. c) The cell presented in panel b stained for CK18 shows cytoplasmic staining with an accumulation of CK18 immunoexpression in the perinuclear space (arrowhead). d) The same cell in CK18 (brown) and ZP (blue) double color immunostaining (CK/ZP) shows high density of ZP expression in the perinuclear space (compare with panel c). e) Control staining shows no reactions in OSE cells when the anti-HLA DR antibody was used in place of the primary antibody. f) A cluster of cells exhibiting epithelial phenotype shows nuclear ZP expression (arrowhead) and differentiation into large cells (arrows). g) Another cluster subjected to the ZP/CK,5,6,8,17 double staining shows dark-blue staining of smaller epithelial cells (arrowhead), which diminishes in more differentiated larger cells (arrow). Bar in (a) for a-e.