[Autoradiographic investigations on postnatal proliferative activity of the matrix-zones of the brain in the trout (Salmo irideus) (author's transl)].

The localization and proliferative activity of the matrix-zones has been investigated in the brains of 60 teleosts (Salmo irideus) by means of autoradiographs, after injection of tritiated thymidine at different stages of the postnatal life. There are no previous detailed autoradiographical reports on postnatal brain development in the trout. Matrix-zones (i.e. ventricular and subventricular zone) exist postnatally in all parts of the teleost brain: we have found these in the forebrain, in many diencephalic recessus, in the optic tectum, in cerebellar valvula and corpus, and in the medulla. The quantitative part of this study indicates high values of the labeling-index at the first days after birth. Then, the labeling-index decreases rapidly up to the 25th day. But also in 2 years old specimen labeled cells were observed in the matrix-zones of the central nervous systems; therefore a few of proliferative capacity remains in adult fishes.