Fig. 1. Expression of Mash1 and Ngn2 in the developing ventral midbrain. (A) Embryonic brains were cryosectioned along the red (B-D,G-H) and blue (E,F) lines, and the immunohistochemical images were taken from the areas in red (B-D,G-H) and blue (E,F) boxes with confocal microscopy. (B-D) Localization of Mash1 expression in AHD2-positive DA progenitor cells in the ventral midbrains at E11 (B,C) and E12 (D). The boxed area of B is magnified in C. Panel C shows micrographs of the z-stacked confocal picture along the y-axis (right) and the x-axis (upper). (E,F) Expression patterns of Mash1 and TH in the E13 ventral midbrain. Note that TH expression is confined to the mantle region in the ventral midbrain at E13, whereas Mash1 is expressed in the proliferating ventricular region. Panel F is a higher magnification image of the white boxed area in E. The expression pattern of Ngn2 in the embryonic ventral midbrain is shown in panels G-I. Ngn2 expression is not detected in the ventral midbrain at E12 (G). Inset, Ngn2 expression in the diencephalic area at E12 (positive control). Ngn2-expressing cells are detected in the ventral midbrain at E13 (H,I) and a subpopulation of AHD2-positive cells co-express Ngn2 (I). Bars, 10 µm.