Wheat germ agglutinin indicates the commencement of neuronal differentiation in the embryonic brain. A comparative...

Paraffin sections prepared from prenatal rat brain (embryonic days 14, 16, 18 and 20) were incubated with buffered wheat germ agglutinin labelled with fluorescein isothiocyanate (FITC-WGA). In the embryonic brain, the proliferating cells of the ventricular zone showed a low binding of WGA. Differentiating neuroblasts and axonal bundles exhibited a significantly higher degree of labelling. This pattern was most evident in the cerebral cortex where the marginal zone and the sub-plate region were found to be most intensely strained. The structural basis of WGA-binding was specified by comparison with data obtained by the colloidal iron hydroxide staining procedure, the periodic acid Schiff's reagent method and Alcian Blue staining (critical electrolyte concentration method). The results show that at regions of intensive differentiation in the embryonic brain there is an increase in the concentrations of sialic acid and glycosaminoglycans.