Ultrastructural Changes in the Developing Rat Cerebellum in Chronic Undernutrition

Abstract

Ultrastructural changes in the developing rat cerebellum in chronic under‐nutrition An ultrastructural study was made of the effects of undernutrition during the first three weeks of postnatal life on the development of the rat cerebellum. Undernutrition was induced in newborn rats (Sprague‐Dawley strain) by increasing the litter size to eighteen pups per dam, versus six pups per dam for the controls. The undernourished rats grew slower and at 22 days of age their average body weight was about 42% of the mean control weight. Electron microscopic examination revealed pronounced and specific changes in the presynaptic terminals and nerve fibers, and in the astrocytes. The synaptic changes were characterized by the presence of membranous whorls of varying densities, and by the accumulation of glycogen particles. Many nerve fibers, myelinated and unmyelinated, showed bizarre configurations of membranous whorls and vesicular profiles in the axoplasm. The myelin sheaths appeared intact. No alterations were observed in the nuclei and perikarya of the Purkinje, granule, basket and stellate cells. Among the neuroglial elements, the Bergmann glia and the astrocytic processes showed large accumulations of glycogen particles. The changes in the presynaptic terminals and axons were interpreted as degenerative, whereas those in the astrocytes as reactive.