EFFECTS OF UNDERNUTRITION DURING THE SUCKLING PERIOD ON GROWTH OF THE ANTERIOR AND POSTERIOR LIMBS OF THE MOUSE ANTERIOR COMMISSURE

Abstract

The anterior and posterior limbs of the anterior commissure were examined quantitatively in normal mice, and mice undernourished during the suckling period. There was no change in the mean length of the anterior commissure in either group. The total number of axons, the percentage of myelinated axons, and the mean number of myelin lamellae remained unchanged between each group in both limbs. There was, however, a highly significant fall in the total number of cells in both the anterior (P<0·001) and posterior (P<0·001) limbs, mainly in the oligodendrocyte fraction of the population. There was no change in the relative proportion of cells in each limb. The cross‐sectional area of both the limbs was significantly less in the undernourished animals, with the posterior limb being affected more than the anterior limb. These differences were found to be due to a significant (P<0·001) fall in the mean diameter of myelinated axons in the anterior limb and to a significant (P<0·001) fall in the mean diameter of unmyelinated axons in posterior limb. The mean diameters of the unmyelinated axons in the anterior limb, and of the myelinated axons in the posterior limb remained unchanged. The possible reasons for these changes, and their place in the general pathology of deficits and distortions following early undernutrition are discussed.