[Mechanisms for encoding positional information in embryonic shaping of the vertebrate brain]

The mechanisms of early embryonal shaping of the brain in man and animals were studied. Analysis of the biomechanical properties of development of nervous tissue and embryological experiments demonstrated that tangential neuroepithelial intention is the major source of positional information. Experimental changes in the neuroepithelial intention system resulted in various types of embryonal anomalies of the nervous system. Mechanism-dependent ion channels that have marked periods of sensitivity and determine the histogenetic direction of neuroblast cell differentiation were found to underlie the mechanosensitivity of the neuroepithelium. Experimental findings were compared with unique autopsy data on early development of the human brain. Human embryos were examined from neurulation to week 6 of development. Different types of human embryonal brain anomalies were shown to occur with 3 types of neurulation disorders: 1) an open preneuropore is responsible for anomalies of the forebrain and ethmoidal area; 2) arrested neurulation in the postneuropore leads to anomalies of the diencephalon, midbrain, and occipital region; 3) impaired neurulation in the caudal region is a cause of spinal cord anomalies. The above anomalies resulted from local compensatory responses of the neuroepithelium due to the lack of intentions that are characteristic of normal development of the neural tube.