Morphologic evidence for a delay of neuronal maturation in fetal alcohol exposure

Qualitative analysis of deep neocortical pyramidal cell dendritic structure was carried out using Golgi staining techniques to visualize the neurostructure. Subjects were neonatal rats whose mothers were exposed to 5% ethanol in a protein-enriched liquid diet. Control groups consisted of pups from mothers pair-fed an isocaloric diet containing no alcohol and pups whose mothers received standard rat chow. Pyramidal neurons of somatic sensory-motor cortex in newborn animals exposed to ethanol had less extensive dendritic arbors. Somata were smaller and rounder than control neurons. These characteristics of neuronal structure suggest that fetal alcohol exposure caused a delay of neuronal development evident at birth. The impact of alcohol on dendritic growth may occur through metabolic effects on the developing neuron. Recent suggestions that alcohol exposure may cause abnormalities of axonal distribution implicate deficient afferent supply as an additional factor in neuronal retardation.