EFFECTS OF PRENATAL ALCOHOL EXPOSURE ON THE POSTNATAL MORPHOLOGY OF THE RAT OCULOMOTOR NUCLEUS

Morphological development of the rat oculomotor nucleus was investigat ed on postnatal day 15 following a prenatal ethanol exposure. Analysis of toluidine blue stained plastic sections showed that the prenatal a lcohol exposure caused a decrease in the density of neurons and an inc rease in the density of astrocytes in the center of the nucleus. There was an alcohol-induced reduction in the overall size of the cross-sec tional region of the oculomotor nucleus, but no effect on the number o f neurons per unit area of that total oculomotor region, indicating a delay or alteration of the migration of neurons to their normal cluste red position in the center of the nucleus. The areas of the neuronal c ell nucleus and nucleolus were not affected by the alcohol exposure. A nalysis of Golgi-Cox-impregnated multipolar neurons showed that the al cohol exposure caused a reduction in area of the cell soma; a reductio n in the number of dendritic branches; and a reduction in the complexi ty of the dendritic arbor relative to distance from the soma, based on concentric ring analysis. The results of this study demonstrate that gestational alcohol exposure can retard the maturation of the oculomot or nucleus. (C) 1995 Wiley-Liss, Inc.