STRUCTURAL ORGANIZATION OF THE MARGINAL AND THORACIC NUCLEI OF THE POSTERIOR HORNS OF THE HUMAN SPINAL CORD IN THE PRENATAL PERIOD

Abstract

Background. Embryology is the fundamental study that provides insights into the formation stages of the central nervous system and the mechanisms involved in its development. Thus, we can establish clear time intervals for thoracic and marginal nuclei formation during intrauterine development. Aim: To investigate the morphogenesis of the marginal and thoracic nuclei of the posterior horns of the human spinal cord during intrauterine development. Results. In the period of 7-8 weeks of gestation, the first signs of the formation of the thoracic nucleus appear, while for the marginal - 9-10 weeks of gestation. Glial cells are companion cells that always surround neurons. In turn, the cells of each nucleus are characterized by uniformity and similarity in shape and size. At 11-12 weeks of gestation, the thoracic nucleus acquires a typical oval shape. The marginal nucleus begins to separate from the gelatinous substance. Clear boundaries of the thoracic nucleus with its inherent oval shape, in comparison with the marginal one, are formed earlier. We found them in 14-15 weeks of gestation. At the same time, the marginal nucleus is separated from the surrounding structures in 20-21 weeks of gestation. By 29-30 weeks, the thoracic and marginal nuclei finish forming boundaries and occupy positions according to the topography, but the process of neuronal differentiation continues until birth. Conclusion. Understanding the stages of fetal development is critical for ensuring healthy pregnancies. So, considering the data we obtained, it became clear that the thoracic nucleus begins to form earlier than the marginal one. The difference in period is on average 3-4 weeks of gestation. Later, the thoracic nucleus acquires its characteristic shape, while the peripheral nucleus begins to separate from the surrounding tissues. The 29-30th week of gestation is characterized by the completion of the formation of both nuclei and their location by their inherent topography.