Fig. 6. Analysis of cell proliferation and apoptotic cell death in Mab21l1^+/- and Mab21l1^-/- lens placodes. Immunohistochemical detection of BrdU incorporation in Mab21l1^+/- and Mab21l1^-/- embryos at various somite stages (A-H). Brackets (D,F) indicate reduced incorporation of BrdU in Mab21l1^-/- small lens placodes. Red dotted lines indicate a Mab21l1^+/- lens vesicle (G) and a Mab21l1^-/- malformed lens placode (H). The inset shows a HE-stained serial section of the area within the box (H). TUNEL assay of 35-somite stage Mab21l1^+/- (I) and Mab21l1^-/- (J) embryos. Numbers of TUNEL-positive cells are slightly increased in the Mab21l1^-/- lens pit (arrowheads). Histogram showing the percentage of BrdU-positive cells in Mab21l1^+/- and Mab21l1^-/- lens anlages (K). The ratio of BrdU-positive cells is reduced in the Mab21l1^-/- mutants (t-test; 27 and 32-somite stages, P<0.004; other somite stages, P<0.0001). Vertical bars represent standard errors. lp, lens placode; lv, lens vesicle; ov, optic vesicle; pi, lens pit; se, surface ectoderm. Scale bars: 50 µm.