Fig. 4. Injection of ChABC modifies the architecture of the ventricular zone. (A) Phase-contrast photomicrographs of E14.5 mouse forebrain cryosections obtained 1 day after intracerebroventricular injection (ICVI) of ACSF (left panels), ChABC (middle panels) or keratanase (right panels). The upper panels show low-power DIC images, and the lower panels are high-power images of histological stainings. Cryosections of control- or keratanase-injected embryos appeared normal with a clearly defined tissue stratification. By contrast, a conspicuous disorganization of the germinal regions (VZ and SVZ) and an accumulation of cells in the normally positioned cortical plate was observed after injection of ChABC (middle panels). Note that the outer layers of the marginal region appeared comparable to those of the control (i.e. after ACSF injection). (B) The efficiency of ChABC injection was controlled by immunostaining with Mab 473HD. Photomicrographs of cryosections from embryos injected with ACSF (upper panels), ChABC (middle panels) or keratanase (lower panels). The 473HD epitope was almost completely absent after ChABC injection, whereas the reaction of the polyclonal antibodies with the RPTP-ß protein cores (KAF13) was unaltered. The 473HD and KAF13 stainings appeared unaltered by keratanase. Cell nuclei counterstained with bisbenzimide are shown in blue (DAPI). Cor, cortex; cp, cortical plate; e, surface ectoderm; ge, ganglionic eminence; imz, intermediate zone; lv, lateral ventricle; m, marginal zone; sep, septum; svz, subventricular zone; vz, ventricular zone. Scale bars: 100 µm.