Figure 3

Five-day OSE culture maintained in the DMEM-HG medium with phenol red as in Fig. 2. a) Cell of oocyte phenotype with two nuclei. The centrally located nucleus shows ZP immunostaining (arrowhead) but adjacent nucleus is unstained (arrow). Note ZP+ intermediate filaments. b) The same cell subjected to double color (ZP/CK5,6,8,17) immunohistochemistry shows no additional (dark blue) staining. c) Another large cell stained for vimentin shows expression in intermediate filaments and two unstained large nuclei (arrows). d) Double color CK18/ZP staining shows intermediate filaments and ZP+ centrally located nucleus (arrowhead) and unstained adjacent structure resembling the polar body (arrow). e) Cell with centrally located ZP+ nucleus (arrowhead) and unstained fragmented adjacent structure (arrow). Note a lack of ZP+ intermediate filaments (compare with panel a) and surface ZP expression (solid arrow; compare with black arrow, panel d). f) Nuclear expression (arrowhead) of meiotically expressed PS1 carbohydrate ZP antigen. Note focally enhanced (coarse) staining (arrow) in one of the two rounded structures. g) Two cells showing a lack of nuclear PS1 expression (arrowheads), but strong staining is associated with adjacent polar-like bodies (arrows).