FIG. 3.

Primordial and primary follicles do not exhibit classic apoptotic pathway endpoints. DNA fragmentation as indicated by TUNEL staining can be recognized in antral follicles (A) from Day 26, but not in primordial follicles (B). DNAse treatment serves as a clear positive control (C), and the image of an entire Day 10 ovary demonstrates global absence of DNA fragmentation at this day (D). Trend shown in A and B is true across the period (C). The same results can be seen for the cleavage of PARP1 (F–H). Western blots show that cleaved PARP1 increases significantly at Day 19 (I). Different lowercase letters indicate a significant difference between groups. Yellow asterisks indicate representative primordial follicles. Error bars are + SEM. P, primordial or primary follicles; S, secondary follicles; A, antral follicles. Bars = 100 μm (A, C, D, F) and 25 μm (B, G).