[Quantitative aspects of the ontogenic development of the visual regions of the brain].

Quantitative light-microscopic studies on the ontogenetic development of 11 visual brain regions of Tupaia belangeri were done. The fresh volumes of the visual brain regions showed a heterochronical and heterotypical development. Brain regions with overshooting or monotonously increasing growth could be found using computer calculations of logistic curves. Studies on the development of the number of nerve cells and glial cells showed an overshooting growth of the nerve cell quantity and a monotonously increasing growth of the glial cell quantity in the nuclei nn. oculomotorii et trochlearis. A compartment analysis with computer aided stereological procedures was done for the nucl. n. oculomotorii. The present findings as well as those from proceeding investigations serve as the basis for a hypothesis describing the significance of the growth curve for fresh volumes, and especially for the spontaneous degeneration of neurons in the formal genesis of the nervous system.