[Spontaneous degeneration of neurons of the Nucl. tractus mesenceph. n. trigemini during the perinatal period of an ontogenic series of Albino mice].

The spontaneous degeneration of neurons of the Nucl. tractus mesenceph. n. trigemini of 33 male NMRI-mice between 19 and 60 days of ontogenesis has been analyzed fitting the exponential function (see article). The number of neurons decreases from 1500 at birth to 1200 at the adult level. The damping of the curve is 4.8. This nucleus is compared with other nuclei of the albino mouse (Nucl. n. oculomotorii, Nucl. cochleares dorsalis et ventralis). The spontaneous reduction of the number of neurons seems to be a common phenomen during the perinatal time of the mammals. There is a heterochronous reduction for the different analyzed nuclei.