Fucosylated glycans in the periventricular structures and the cerebrospinal fluid of the fetal rat forebrain. An autoradiographic and lectin binding histiotopic study

Our autoradiographic H-3-fucose incorporation study of the brains of 20-day -old rat fetuses showed that the synthesis of fucosylated glycans is signif icantly higher in the ventricular germinative zone of the forebrain hemisph ere than in the more superficial layers, including the cortical plate. Inte nse incorporation of H-3-fucose also occurred in the choroid plexus, both i ts epithelial and stromal component. in the primordial ependymal lining of the lateral ventricles, meninges and capillaries of the forebrain parenchym a. In the lateral ventricles, densely labeled microprecipitates of the cere brospinal fluid (CSF) were occasionally observed. The histiotopic differenc es in H-3-fucose labeling were absent, or were much less expressed, in the autoradiograms prepared from unfixed cryostat sections containing mainly un incorporated isotope. This indicates that the blood-mediated supply of H-3- fucose to the studied brain compartments was essentially equal and our inco rporation data reflect actual differences in the rate of fucosylation withi n the forebrain hemispheres. The cytochemical lectin-binding assay, carried out with Ulex europaeus and Lotus tetragonolobus agglutinins, showed that regions with a higher rate of H-3-fucose incorporation were also richer in fucose-bearing glycoconjugates. The study revealed that the periventricular regions and the CSF of fetal rat forebrain form a fucosylated glycan-enric hed complex, which represents a new chemoarchitectonic feature that may be of importance for maintaining the germinative properties of the ventricular neuroepithelium and the growth of the hemispheric ventricles. (C) 2001 ISD N. Published by Elsevier Science Ltd. All rights reserved.