Fig. 2.

Mef2c is required for melanocyte development in mice. (A-D) Whole-mount DOPA-stained epidermis (A,B) or dermis (C,D) from Wnt1-Cre^Tg/0; Mef2c^flox/+ control (A,C) and Wnt1-Cre^Tg/0; Mef2c^flox/− neural crest knockout (NC KO; B,D) neonatal mice showed many fewer stained follicular (white arrowheads) and interfollicular (black arrowheads) melanocytes in Mef2c NC KO skin compared with controls. (E) Quantification of DOPA-stained melanocytes from Wnt1-Cre^Tg/0; Mef2c^flox/+ control and Wnt1-Cre^Tg/0; Mef2c^flox/− NC KO epidermis. Filled circles represent individual control mice (191±16 DOPA-stained melanocytes per sample, n=7) and open circles represent individual Mef2c NC KO mice (25±10 DOPA-stained melanocytes per sample, n=9), P<0.0001. (F,G) Electron micrographs of DOPA-stained melanocytes from Wnt1-Cre^Tg/0; Mef2c^flox/+ control mice (F) and Wnt1-Cre^Tg/0; Mef2c^flox/− NC KO mice (G) showed that Mef2c NC KO mice had fewer melanosomes per melanocyte (black arrows). (H) Quantification of melanosomes in individual DOPA-stained control and Mef2c NC KO neonates indicated the mean number of melanosomes in 100 μm² for control skin was 31.7±6.8; n=3 mice. The mean number of melanosomes in 100 μm² within stained melanocytes in Mef2c NC KO neonates was 11.0±0.6; n=3 mice (P=0.038). An average of six randomly selected melanocytes from each neonatal mouse was scored. Data are expressed as the mean number of melanosomes in 100 μm² + s.e.m.