Synapses and malnutrition: quantitative ultrastructural study of rat cerebral cortex

In a previous study we have found that synaptosomal fractions from cerebral cortex of 24-day-old rats malnourished from late gestation yielded more protein and higher enzyme activities than the controls, suggesting that presynaptic endings may be relatively "spared" during malnutrition. In order to explore further the effect of malnutrition on presynaptic endings, we have carried out a quantitative ultrastructural study of the lamina pyramidalis from the somatosensory cortex of rats identical in age and method of malnutrition to those used in the previous study. The fractional area of the cortex occupied by cell bodies was 53% larger in the malnourished animals than in the controls. This increase was due to a higher density rather than a larger size of the cell bodies. Neurons accounted for almost all the increase of cellularity while no conclusion could be reached for the glia. The fractional area occupied by neuropil was decreased by 7.4%. The fractional area of the neuropil occupied...