Morphogenesis of the human brain and cerebellum in the early prenatal period

Abstract

Annotation. Neurogenesis is a complex process of neuron formation that is central to the formation of most neurons in the human brain during vertebrate development. The purpose of this study was to establish and compare the parameters of the cerebellum and the endbrain of humans at 8-9 weeks of intrauterine development, as well as the features of cytoarchitectonics, which is inherent in the studied period of gestation. In the process of scientific research, 10 fetuses of 8-9 weeks were examined and research methods were applied, such as: immunohistochemical, anatomical-histological and morphometric. The morphometric study was carried out using a light microscope MBS-10 and SIGETA. Studies were performed at magnifications of ×4, ×10, ×20, ×40, and ×100. From the obtained histological sections, photofixation and morphometry were performed using the ETREK Ucmos camera and the ToupViem computer program (computer histometry). Statistical processing of digital data was applied using the software package “Statistica 6.0” from Statsoft (license number BXXR901E246122FA). During the study, we observed that the total thickness of the studied area varied depending on the part of the endbrain. In the hemispheres of the endbrain of 8-9 week fetuses, the presence of such layers as ventricular, subventricular, intermediate and cortical was noted, whereas examining the cerebellum, we witnessed the presence of the ventricular zone, intermediate, molecular and external granular zone. The expression of proliferated neural stem cells in the layers of the endbrain was the most active in the ventricular zone, compared to the others. Migration of neural stem cells in the cerebellum, in the ventricular and external granular zones occurs in two directions: tangential and radial. Weak expression of synaptophysin is observed in the cerebellum. In the endbrain, synaptophysin expression was strong in the intermediate and cortical zones. Fibers of radial glia of an 8-9 week fetus penetrate all zones of the endbrain and cerebellum. On a horizontal histological section of the terminal brain of human fetuses, the cavities of the ventricles were visualized and the development of vascular plexuses in the lateral ventricles of the brain was noted. Thus, in the course of the research, we compared the features of cytoarchitectonics, morphometric parameters of the structures of the endbrain and cerebellum of human fetuses of 8-9 weeks of intrauterine development.