Expression of MECP2 in the ovary (A) and testis (B). Only young oocytes (A1, arrows) express MECP2; the more mature oocytes (A2) do not express MECP2 (A2, empty arrow). Neighboring follicular cells (arrowheads) strongly express MECP2. In testis, only Sertoli cells (B2, arrowhead) and fibroblasts (B2, arrows) express MECP2; spermatocytes at all stages of maturation and sperm cells are MECP2-negative. Single confocal sections. Scale bars: (A1, A2) 25 μm, (B1) 50 μm, (B2) 10 μm.