Immunohistochemistry showing localisation of germ cells and 5mC during mid to late gestation. In order to clearly show the localisation of germ cells at all stages of development, we used the specific germ cell cytoplasmic marker DAZL, which survives acid denaturation, in combination with 5mC for immunohistochemistry. The cytoplasm of germ cells is stained for DAZL in blue and 5mC is indicated by brown staining in nuclei. Germ cells (indicated by yellow arrows) are located within seminiferous cords which are surrounded by somatic cells; one seminiferous cord is shown outlined in each image. There are also somatic cells within the seminiferous cords (green arrows). Images show that 5mC is undetectable in germ cells between e14.5 and e18.5 (A to E). 5mC is detectable in germ cells at e19.5 (F, indicated by red arrow) and is more marked in germ cells at e20.5 and e21.5 (G, H). 5mC is present in somatic cells throughout the time course. Scale bar = 50 μm.