Fig. 4

Histopathological examination of ovarian tissues. Photomicrographs (× 100) show HE stained ovaries. a Control group. b POF group. c MSC group. d NC group. e HO-1 group. f shHO-1 group. g DMSO group. h Anisomycin group. i SP600125 group. The five types of ovarian follicles were marked as (1) primordial follicles, (2) primarily follicles, (3) secondary follicles, (4) antral follicles, and (5) atresia follicles. j–l Quantitation on follicle count from ovaries in mice of the nine groups. Data presented as mean ± SD. *P < 0.05, **P < 0.01, ***P < 0.001 vs DMSO, GC group, or NC group, separately. Bar scale = 200 μm. DMSO, dimethylsulfoxide; HE, hematoxylin and eosin; HO-1, heme oxygenase-1; NC, empty vector; POF, premature ovarian failure; UCMSCs, umbilical cord mesenchymal stem cells