Fig. 3. Cell death and proliferation in hindbrains of wild type and Krox20 mutant embryos. (A-C) Flat mounted hindbrains of 12 s wild type (A), Krox20^lacZ/+ (B) and Krox20^lacZ/lacZ (C) embryos stained with X-gal (blue) and processed for H3P immunohistochemistry (brown). (D,E) Coronal sections of 14 s Krox20^lacZ/+ (D) and Krox20^lacZ/lacZ (E) embryos whose mothers were injected with BrdU 1 hour before sacrifice. The sections were stained with X-gal (blue) and processed for BrdU immunohistochemistry (brown). (F-M) Flat mounted hindbrains of 8 s (F,G), 12 s (H,I), 15 s (J,K) and 9.5 dpc (L,M) Krox20^lacZ/+ (F,H,J,L) and Krox20^lacZ/lacZ (G,I,K,M) embryos stained for ß-galactosidase activity (blue), and for cell death by the TUNEL method (brown or purple). (N,O) Dissected hindbrains of 9.5 dpc wild-type (N) and Krox20^lacZ/lacZ (O) embryos stained for cell death with Nile Blue Sulphate. Black arrowheads in F,H,I,J,K,M,O point to regions of intense cell death. ov, otic vesicle. Rostral is towards the top.