Morphogenesis of the Upper Jaw and the Adjacent Structures of the Maxillofacial Region in Human Pre-Fetuses Aged 7-9 Weeks of the Intrauterine Growth

Based on scientific sources stury, the authors concluded that the upper jaw in the perinatal period of ontogenesis is characterized by the diversity of the topical position of its processes and walls and predetermines the need for further anatomical studies of its prenatal ontogenesis. Thus, we initiated a new cycle of investigations of morphogenesis of the upper jaw and some structures of the human maxillofacial region with a description of the features of its course in the embryonic period of prenatal ontogenesis. Having completed the first stage of the work, we considered it expedient to continue the study of the morphogenesis features of the maxillofacial region in the dynamics of the pre-fetal period of human ontogenesis in the 7th -9th weeks of fetal development as a prospect of further researches. Objective. The purpose of the article is to examine the features of the morphogenesis of the upper jaw and some structures of the human maxillofacial region in the dynamics of the 7th -9th weeks of the prenatal ontogenesis. Materials and methods. The study was conducted with 39 specimens of human pre-fetuses with 14.2-41.0 mm of crown-rump length (7-9 weeks of intrauterine development) using the methods of macroscopy, morphometry, manufacturing and microscopy of a series of sequential histological sections of human embryonic specimens and that of histochemistry. Results. In the 7th week of the intrauterine growth (IUG) the differentiation of structures involved in the formation of the maxillofacial apparatus progresses more rapidly compared to such processes at the previous stage of development (embryos aged 6 weeks of IUG). There is a convergence of the frontal and lateral nasal processes that form the upper jaw. Osteogenesis progresses developed more actively in the mandible. There are foci of mesenchyma condensation in the upper jaw, which begin to turn into osteogenic islets. The oral cavity vestibule is formed, an anlage of the dental plates takes place, and by the end of the week there is an anlage of the tooth buds. Mimic and chewing muscles can be identified. At the same time, the lagging of histogenetic transformations in the maxillary rudiments compared to the mandibular ones continues. At the end of the 8th week of the human IUG morphogenetic processes in the maxillofacial apparatus were characterized by further transformations, resulting in the formation of a solid base of the jaws, and its surrounding soft tissues lose the features characteristic of mesenchyma, transforming into the structures of loose fibrous connective and muscle tissue. Corresponding progressive changes are also observed in ectodermic derivatives of the maxillofacial apparatus, which are involved in the formation of the oral cavity vestibule and the dental rudiments. As a result of the 9th week course of human IUG there is a number of formative processes that are accompanied by further complications of intercellular and inter-tissue relations in heterogeneous rudiments of organs and structures of the maxillofacial region in pre-fetuses, which cause the formation of the secondary oral cavity.