Ab49602

Embryonic gonads were fixed in 4% PFA for 30 min at 4°C. Gonads were next submerged in 10 and 20% sucrose in PBS for 1 h each at 4°C, and in 30% sucrose in PBS overnight at 4°C. The gonads were then embedded in Tissue-Tek O.C.T. compound (Sakura Finetek) and frozen in liquid nitrogen. Six-micrometer-thick sections of each gonad were applied to glass slides and autoclaved in TRS (Dako). After pre-incubation with 3% skim milk in PBS-T (PBS with 0.1% Tween20 (Sigma-Aldrich)) at RT for 30 min, the sections were reacted with primary antibodies overnight at 4°C at the following dilutions: 1:200 for mouse anti-phospho-histone H3 (ser10) (1:200, Sigma-Aldrich, 06-570), goat anti-CDH1 (1μg/ml, R&D, AF748), rabbit anti-DNMT3L (1:500, provided by Dr. Yamanaka), rabbit anti-STRA8 (1:200, abcam #ab49602), rabbit anti-Ki67 (1:200, Invitrogen #MA5-14520), rat anti-Ki67 (1:100, Invitrogen AB_10854564) and anti-pS6 (1:200, CST #2211). Secondary antibodies labeled with Alexa 488, 594 or 647 (1:1,000, Invitrogen A21207, A21208, A21209, A32766, A32814, A32754, A32744 and A32795) were used. DNA was counter-stained with DAPI (100 ng/ml). Fluorescence microscopy was performed using Olympus FV1200 and images were processed with ImageJ/Fiji (Schindelin et al., 2012 (link)).