Figure 4

Follicular renewal in adult human ovary and intravascular degeneration of germ cells unattended with granulosa cells. A) Ovarian vein in the lower ovarian cortex lined by endothelial cells (en) and CK+ granulosa nest wall (gnw). In the vein lumen (vl) the granulosa nest wall extends a granulosa nest arm (gna) capturing the circulating oocyte (co). B) Granulosa nest (gn) during formation of the new primary follicle with captured oocyte. Granulosa cells penetrate the ooplasm (red arrowheads) during the primary Balbiani body (asterisk) formation adjacent to the oocyte nucleus (on). CK+ granulosa nest particles (yellow arrowheads) are already dispersed within the oocyte, which still exhibits oocyte tail (ot) outside of the new primary follicle. C) Growing follicle (dashed line circle), with granulosa cells (grc) and oocyte (o) with ZP expression at the oocyte surface (arrow). D) Degenerating oocyte in a medullary vein from the same ovary as in panel C exhibits a strong cytoplasmic ZP expression. E) Heavily ZP+ degenerating oocyte from 28 year-old fertile woman found in the extra ovarian (uterine ectocervix) vein of a patient with follicular renewal shown in panels 4A and 4B. Panels A and B adapted from Ref. [23] : © Antonin Bukovsky; panels C-E adapted from Ref. [41] , with a permission: © Elsevier/North-Holland Biomedical Press.