Screening germ cell development using organ culture and flow cytometry. A. Organ culture system showing brightfield (upper middle) and fluorescence (lower middle) images of E12.5 testes cultured for 72 hours. B. Flow cytometric output for (i) germ and somatic cells separated on the basis of MVH staining and proliferation of (ii) germ cells and (iii) somatic cells assessed by EdU staining in DMSO and PD0325901 treated gonad samples cultured for 72 hours.