Fig. 6. Genital ridge organ cultures showing the time course of testis-specific glycogen accumulation (A) and testis-specific induction even in serum withdrawal (B). (A) Sagittal sections of genital ridges cultured with 10% horse serum-DMEM for 6, 12, 24 and 48 hours and stained with PAS. In XY explants isolated at 12 ts, PAS-positive cells are detected after being cultured for 6 hours (arrow in XY 12ts), and then rapidly increased in the gonadal area near germ cells from 12 to 24 hours. In XY genital ridges isolated at 10 ts, PAS-positive cells are induced in the gonadal region at 12-24 hours (arrow in XY 10 ts). By contrast, no PAS-positive cells are detected in the gonadal region of XX genital ridges even after being cultured for 48 hours (XX 12 ts). (B) Sagittal sections of XY (left and middle) and XX (right) genital ridges (12 ts) after 48-hour culture in medium with or without 10% horse serum and stained with PAS. Despite severe growth defects in the genital ridges, PAS-positive cells are found to be induced in the gonadal area of the XY, but not XX, genital ridge, suggesting no appreciable effect of serum withdrawal on sex-dimorphic glycogen deposition in vitro. ms, mesonephros. Bar, 50 µm.