[Neurogenesis and regeneration in the brain of teleosts in relation to age. (Autoradiographic studies)]

54 healthy female Lebistes reticulatus and 11 Xiphophorus helleri of various age groups were injected with 3H-thymidin. The duration of the radio-active test was one hour. By means of autoradiograms of serial sections of the brain, the post-natal persistence of matrical zones was demonstrated in the telencephalon, diencephalon, mesencephalon, cerebellum and in the medulla oblongata. The age-dependency of the 3H-thymidin index produced the same results in all matrical zones: high values in young animals, followed by a steep decrease and a steady state in older animals. In 30 other laboratory animals (Lebistes reticulatus-Teleostei), out of which 15 were juvenile and 15 were adult females, a unilateral lesion of the central tectum was effected. On the 5th, 7th, 8th, 15th, and 25th days following operation the animals were given a single injection of 3H-thymidin (absolute activity 10 muCi/g body weight; duration of the radio-active test: one hour). Labelled meningeal cells were observed in the traumatic region. In the course of regeneration there takes place a migration of cells into the puncture channel. No labelled cells were observed in the tissues adjacent to the lesion nor in the cell column. The proliferation of cells takes place in the matrical zones. By determining the 3H-thymidin index we were able to show that the proliferation activity is being increased. In the matrical zones of the non-operated tectum opticum too, the number of DNA synthesizing cells is increased.