FEATURES OF THE EARLY MORPHOGENESIS OF THE CENTRAL NERVOUS SYSTEM
Authors: Khmara T. , Tsyhykalo O. , Zamorskii I. , Pankiv T. , Komshuk T. , Smetaniuk O. 
Published: December 2024

One of the urgent tasks of modern medicine is the prevention of brain damage during the human fetal period and the creation of conditions that ensure proper brain development.
Objective of the research. To find out the features of the early morphogenesis of the central nervous system in the embryonic and early pre-fetal periods of human ontogenesis.
Methods. The study of the early stages of the formation of the brain and spinal cord was carried out on 14 embryos and 12 human fetuses with 4.5-20.0 mm parietal-caudal length (PCL) by the methods of microscopy, three-dimensional computer reconstruction, morphometry, and statistical processing of digital data.
The investigations were performed keeping to the major regulations of the Resolution of the First National Congress on Bioethics «General Ethic Principles of Experiments on Animals» (2001), ICH GCP (1996), the European Union Convention on Human Rights and Biomedicine (04.04.1997), and the European Convention for the Protection of Vertebrate Animals Used for Experimental and Other Scientific Purposes (18.03.1986), the Declaration of Helsinki on Ethical Principles for Medical Research Involving Human Subjects (1964-2008), EU Directives №609 (24.11.1986), the Orders of the Ministry of Health of Ukraine № 690 dated 23.09.2009, №944 dated 14.12.2009, № 616 dated 03.08.2012.
The work is carried out within the framework of the initiative research work of the Department of Histology, Cytology and Embryology of Institution of  the Bukovinian State Medical University "Structural and functional peculiarities of tissues and organs in ontogenesis, regularities of variant, constitutional, sex-, age-related and comparative human morphology". State registration number: 0121U110121. Terms of execution: 01.2021-12.2025.
Results. There is a close relationship between the development of the cerebral cavity, in particular, its ventricles, and the morphogenesis of the corresponding parts of the brain. In the process of complications in the structure of the ventricles of the brain, namely during the formation of the vascular plexus, disturbances can occur, which cause defects in the subsequent stages of ontogenesis. On the basis of the above, this period (the 6th week of embryonic development) can be classified as critical.
Conclusion. In embryos of 6.0-8.0 mm PCL, the formation of primitive, without the formation of corresponding parts, lateral ventricles and the third ventricle of approximately elliptical shape is determined. In embryos of 9.0-12.0 mm PCL, the contours of the medulla oblongata are defined, which is a continuation of the spinal cord, the central channel of which forms the cavity of the fourth ventricle in the shape of a diamond. At the end of the embryonic period (embryos 12.0-13.5 mm PCL), accelerated development of the terminal and hindbrain is observed, which leads to a change in the configuration of the brain cavity, in which the anterior and lower horns of the lateral ventricles can be distinguished. At 16.0-18.0 mm PCL of human fetuses, the formation of the cerebral vascular plexus begins, which is represented by insignificant folds with barely noticeable protrusions on the ependymal membrane of the brain cavity.