FIGURE 6.

Nissl-stained brain sections from GnT-Vb and -V double knock-outs show no obvious malformations or changes in cell number or architecture. Thin (3 μm) sections from wild type (Wt) and GnT-Vb and -V double knock-outs were analyzed histologically and using stereological cell counts to determine whether loss of these two enzymes alters brain structure. We found no obvious changes in the morphology of the brain and therefore no changes in the cell number or cellular organization of the brain. These data argue that GnT-Vb and GnT-V are relatively dispensable for normal brain development. Modification of O-mannosyl glycans by these enzymes does not contribute any phenotypes similar to those found in CMDs.