Astroglial interlaminar processes in human cerebral cortex: variations in cytoskeletal profiles

Abstract

Among mammalian species, astroglial interlaminar processes are unique features of the primate cerebral cortex. The morphological diversity in the immunocytochemical expression of their cytoskeleton was analyzed. For this purpose, samples from normal human cerebral cortex from autopsy cases were used. While Fractal dimension failed to represent the actual complexity of interlaminar processes, Compression analysis allowed classification of these profiles according to their relative tortuosity. Conversion of Compression values into estimates of membrane surface suggested that profile changes could not only affect the directionality of dynamic events, but also the amount of glial cell membrane exposed to the local neuropil. Terminal segments of interlaminar processes were usually more tightly twisted than the cytoskeleton stalk, and enlarged in aged individuals. If not aberrant structures, these so-called ‘terminal masses’ may provide an additional means to increase local membrane availability. Based on Compression analysis, categories of the geometric variability of the cytoskeleton of cerebral cortex interlaminar glial processes are presented.