Association of PS1 meiotically expressed oocyte carbohydrate protein with asymmetric division and migration of putative germ cells. A) Segments of SE show cytoplasmic PS1 (brown color) expression (se). Dividing SE cells give rise to cells exhibiting nuclear PS1 immunostaining (+ nuclei, asymmetric division) and descending from the SE (arrows) into tunica albuginea (ta). This is particularly evident in the cell marked with a red arrow. B) Except asymmetrically divided SE cell – note CK+ (blue color and arrowhead) and PS1+ (brown color and arrowhead) daughter cells, no PS1 or CK immunoexpression is apparent in this SE segment or in the panel (C). D) In TA, the putative germ cells increase in size, but nuclear PS1 immunostaining persists. They show a symmetric division (arrow, E) and exhibit development of cytoplasmic PS1 immunoexpression when entering the upper (uc) ovarian cortex (white arrow). In the cortex, the cells show diminution of nuclear and increase of cytoplasmic PS1 staining (white arrow, panel F), particularly when attached to the cortical vessels (v). In such case, the PS1 immunoexpression appears to be extended toward endothelial cells (black arrow). In some instances, the asymmetric division giving rise to the putative PS1+ (brown color) germ cells could be observed at the periphery of CK+ (blue color) cortical epithelial crypts (arrow, panel G). Single (PS1) or double color immunohistochemistry (PS1/CK) as indicated, no hematoxylin counterstain.