Figure 12

Epithelial crypts – a source of germ cells for the alternative pathway of primary follicle formation. In ovaries showing atresia of follicular cohorts, association of epithelial nests with epithelial crypts has been observed. Panels (A-C) show CK+ (brown color) small epithelial nests, as evidenced from serial sections (compare the content of solid and dashed squares and oval areas on the left side). In panel (B), weakly CD31+ (purple) adjacent vessel is indicated by a red arrow, solid white arrows in A-C indicate an extension from the crypt toward the nests, and open arrows in (C) – see also lines in (B), indicate interface between stromal sprouts carrying epithelial nests and the crypt. Panel (C) also shows an accumulation of DR+(purple) macrophages around the stromal sprouts, and at their interface in particular. D) Remnant of an epithelial crypt (red arrow) from another case shows migration of ZP+ (HSPZ, blue) particles and stromal staining from one side (arched arrow). E-H) Details from panel D show an appearance of single (yellow arrowheads) and dividing germ-like cells (red arrowheads) among regressing CK+ cells (brown color). Note ZP+ segments (blue color and arrowheads) associated with unstained round cells. Dashed line in (H) indicates tadpole-like germ cell with leading nucleus (dotted line), ZP+ (blue color) intermediate section (is), and unstained tail (t). Panel (I) shows an association of primary follicles with the cortical epithelial crypt. Dashed boxes indicate unassembled epithelial nests. Details in text. No hematoxylin counterstain.