Fig. 5. Proliferation status of WT and Foxl2^lacZ homozygous mutant ovaries. (A-D) High magnifications of Hematoxylin and Eosin stainings showing WT and Foxl2^lacZ homozygous mutant follicles 2 weeks and 8 weeks after birth. (A) Secondary follicle in WT ovaries 2 weeks after birth (black arrow, cuboidal granulosa cells; o, oocyte). (B) Primordial follicles in mutant ovaries 2 weeks after birth (white arrow, squamous granulosa cells; o, oocyte). (C) Preantral follicle in WT ovaries 8 weeks after birth (black arrow, cuboidal granulosa cells; o, oocyte). (D) Atretic follicles in mutant ovaries 8 weeks after birth (black arrow, squamous-like granulosa cells; o, oocyte). (E-H) Detection of apoptosis by TUNEL assay in WT and Foxl2-deficient follicles. (E,F) There is almost no apoptosis detectable in WT or in Foxl2^lacZ homozygous mutant ovaries 2 weeks after birth. (G) An antral follicle in an 8-week-old WT ovary showing apoptotic nuclei in the granulosa cells. (H) Atretic follicles in 8-week-old mutant ovaries stain positive in the squamous-like granulosa cells. (I-L) Staining of control and Foxl2^lacZ homozygous mutant ovaries with an anti-PCNA antibody. (I) Two weeks after birth granulosa cells in primary and secondary follicles stain positive for PCNA, whereas no staining is detectable in Foxl2^lacZ homozygous mutant ovaries (J). (K) Positive PCNA staining in granulosa cells of an antral follicle in the WT ovaries. (L) In contrast, no staining was observed in the mutant ovary.