The number of cells labeled with BrdU and H3 (pSer 10) were counted in five slices (40 μm thick- ness) per gonad. Individually labeled cells were clearly identified in 3D confocal stacks of 3.0 μm optical sections. To identify the epithelial Sox9 þ and Sox9 cells, cytokeratin was used as pre- viously reported (Díaz-Hernández et al., 2012