Testing of the course of neurogenesis and gliogenesis in the germinative zones of the CNS of embryonal and early postnatal rats by means of the gel reaction for the histochemical demonstration of the thiamine-pyrophosphatase. Histochemical and autoradiographical study.
Using the histochemical reaction for the demonstration of TPPase the shape and distribution of the Golgi apparatus (GA) of the ventricular zones of the CNS of rats was studied during embryonal and postnatal development. In the cells of the ventricular zone of the spinal cord, the Hypothalamus, the Thalamus, the N. caudatus and the Cerebral cortex two forms of GA can be distinguished: Form 1 GA has the shape of small rods or grains placed in the ventricular process of the cell at various distances from the nucleus. In the spinal cord and the Hypothalamus the 1st form correlates with the period of neuroblastic production, and the same correlation probably exists in other regions of the CNS also. Form 2 GA is in sequence with form 1; it is characterized by a large beam shape, situated supranuclearly near to the nucleus. The relation of form 2 to gliogenesis is discussed. In the alar region of the spinal cord only form 1 GA occurs. The GA of cells of the subventricular zone has on average a lower enzymatic activity than that of the ventricular zone. By day 18 intra uterinam the subventricular cells have the shape of very small grains (1 micron) or are not visible. From day 18 intra uterinam cells with a large GA begin to appear and steadily grow in number until postnatally they form the majority of the subventricular layer. Autoradiographical investigation and a comparison with published data showed that cells without GA and with discrete GA are stem cells and those with a large GA are glioblasts. Glioblasts are arranged in the subventricular zone with the GA pointing in the direction of migration. According to the ratio of glioblasts and stem cells topographical regions can be divided into early, transitional and permanent phases of glioproduction. The gel method of demonstrating TPPase is highly suitable for study of the differentiation of the CNS and for observing the progress of glioproduction.