[Stereological investigation in the cerebral cortex of aging subjects (author's transl)].

Involving cortical regions, capillaries of the human cerebrum of two 19 and 27 years old men, a 69 years old woman and a 72 years old man were stereologically investigated by optical-electronic image-analysis. The cortical capillary net work was demonstrated by the alkaline phosphatase activity. Each cortex region comprised a determination of the stereological parameters diameter, projected area, specific surface area, capillary distances in linear direction of TV-lines and total length per unit cortex volume. A comparison between different cortex regions revealed a good correlation between increased values of the diameter and the projected area, a decreased specific surface area and diminished capillary distances, which entail a shortened distance of oxygen diffusion through the cortical tissue. During aging a diminished capillary surface area, which results from increased values of diameter and projected area is compensated by shortened capillary distances. Presumably an augmented capillary length is due to a condensation of the capillary net per unit cortex tissue. The behaviour of the registered stereological parameters seems to be an accommodation of the capillary net in the human cerebrum to metabolic and circulatory changes during aging.