Review Volume 1, Issue 2 pp 157—181

Figure 6. Origin of new oocytes (neo-oogenesis), primordial follicles, and SCP3 expression in adult human and monkey ovaries (A-M), and oogenesis in adult rat ovaries (N-P). (A) During asymmetric division (white arrowhead), the CD14 MDC interact with both the OSC daughter (yellow arrowhead) and germ cell daughter (red arrowhead). (B) T lymphocytes, however, interact with the germ cell daughter only (red arrowheads). (C) Ameboid germ cells (dotted line) migrating through the dense ovarian cortex (oc) are accompanied by activated MDC (arrowhead). (D) Asymmetrically dividing OSC produce a new PS1+ germ cell (red asterisk) and CK+ progenitor cell (yellow asterisk). (E) In the tunica albuginea (ta) germ cells (asterisks) symmetrically divide (arrowhead). (F) Capture of oocyte (o) from the blood circulation by an arm (a) of granulosa cell nest (n) lining the venule lumen (vl); e, endothelial cells. (G) Oocyte nest assembly. (H) Segments of tunica albuginea (ta) in ovaries with follicular renewal (early luteal phase) showed strong SCP3 expression of mesenchymal (arrowheads) OSC precursors under ovarian surface (os). (I) Staining of OSC (osc and arrowhead) was apparent in other segments - note lack of staining of tunica albuginea under developed OSC. (J) Postovulatory human ovaries showed staining of oocyte nucleoli (arrowhead) in some primordial follicles. (K) In monkey ovaries, similar staining of oocyte nucleoli in some primordial follicles was observed (red vs. white arrowhead). (L) Staining of paired chromosomes oocyte was observed in human ovaries (inset shows higher magnification). (M) Adult rat testis (positive control) showed staining of condensed chromosomes in spermatogonia (red arrowhead) and progression of meiotic division in primary spermatocytes (black arrowhead). Oogenesis in adult rat ovaries is initiated by asymmetric division of OSC (white arrowhead, N) showing unstained OSC daughter (yellow asterisk) and ZP+ (magenta color) germ cell daughter (red asterisk) accompanied like in human ovaries by a lymphocyte (black asterisk and brown color). Symmetric division of ZP+ oogonia (asterisks, O) follows, and is accompanied (P) by MDC (yellow arrowhead). Blue arrowheads in (P) indicate association of primitive granulosa cells with this process. ZP, zona pellucida; LCA, leukocyte common antigen; W6/25, marker of rat MDC. Details in text. Adapted A-C from Ref. [57], © Blackwell Munksgaard, D-G from Ref. [35], © Antonin Bukovsky, H-M from Ref. [71], © Landes Bioscience, N-P from Ref. [72], © Landes Bioscience.