Fig. 6. GPC4 is required for establishment of Emx2 expression and survival of anterior CNS cells. (A,B) Emx2 transcript distribution during neurulation (stage 17) in CoMo-(A) and Gpc4Mo-injected (B) embryos; frontal views are shown. Emx2 expression in GPC4-depleted embryos is either very low (arrow) or absent. (C-I) TUNEL assays to detect apoptotic cells in neurulating embryos. (C,E,G) CoMo-injected embryos. (D,F,H) Gpc4Mo-injected embryos. Anterior is to the left. (C,D) Fluorescence analysis of cell death on sagittal sections of a stage 17 embryo. Fluorescence was used as it is more sensitive for detection of low numbers of apoptotic cells. Arrows in C and D point to the presumptive forebrain. (E-I) Detection of apoptotic cells by whole-mount analysis of hemi-sectioned embryos (stage 20). Massive cell death is apparent in the brain of Gpc4Mo-injected embryos (F) in contrast to CoMo-injected embryos (E). Boxed areas in panels E and F indicate the enlargements shown in panels G and H. (I) Cell death is rescued in embryos co-injected with Gpc4Mo and mouse Gpc4 mRNA. A, anterior; P, posterior; D, dorsal; V, ventral.

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