Reactive Plasticity of Neuroglial Cells on Brain Lesion

Ahn, E Tay; Ko, Jeong Sik; Park, Kyung Ho

Abstract

Neuroglial cells are actively participate in the pathogenesis or in the recovery procedures following brain lesions. The study was performed to evaluate the plasticity of glial cells following different degree of brain lesions. Neurosurgical operations were made on the rats fixed on the stereotaxic apparatus. Tissue column of 3 mm-diameter was isolated in the caudatoputamen with concomitant severe bleeding in the first group. In the second group, the sensorimotor cortex was suctioned out with moderate bleeding. In the third group, the mammillary body was electrically coagulated with minimal bleeding. Caudatoputamens, as a lesioned tissue or as a target tissue of lesioned area, were studied light and electron microscopically. Observations on reactivities and plasticities of neuroglial cells on the different situations, the following results were obtained : 1. Astrocytes were swollen within an hour following brain lesions. 2. In case of smaller lesion, astroglia alone remove altered structures. 3. Microglia are increased in number, if the lesion is large with severe bleeding. The microglia might come from blood monocyte via transformation to pericyte. 4. In large lesion, astroglia were greatly hypertropied, and microglia might be moving and functioning effeciently within the hypertropied cytoplasm of astroglia. 5. In the stabilizing stage, astroglia produce glial fibers and fix the exhausted microglia. Fixed microglia are proceed into apoptotic process in the cytoplasm of astroglia and removed by them. All these procedures might be controlled by various receptors and secretions of astroglia. It means that astroglia is not only the basic supporting element of nervous tissue, but also an actively functioning element for the most effective homeostatic functioning of the neuropil.