The aim: To find out the sources of formation and the chronological sequence of the morphogenesis of the maxilla at the early stages of human ontogenesis. Materials and methods: 14 series of consecutive histological specimens of human embryos and prefetuses (4,0-66,0 mm of parietal-coccygeal length) aged from 4 to 11 weeks of intrauterine development with the use of a complex of modern morphological methods of investigation (anthropometry, morphometry, microscopy, and 3D computer reconstruction) were studied. Results: On the basis of a complex of morphological research methods, data were obtained that made it possible to establish the general patterns of development of the human maxilla: separation of the pharyngeal apparatus (4th week), convergence and fusion of the jaw processes (5-8th weeks), formation of tooth buds (7-8th weeks), which allows considering the specified periods as critical in the formation of possible anomalies in the facial part of the skull. At the same time, a tendency of heterochrony of morphological transformations in the maxilla and maxilla was revealed. Conclusions: 1. At the beginning of the 4th week of intrauterine development, 3 pairs of pharyngeal arches are formed. Detachment of the mandibular and maxillary processes of the mandibular pharyngeal arch is planned. 2. During the 7th week of intrauterine development, the maximum convergence of the maxillary processes with the lateral and medial nasals occurs, and in embryos of 20.0 mm PCL grow with the frontal process, forming the maxilla and upper lip. During the 8th week of intrauterine development, the bone base of the jaws is modeled as a result of the increase in the size of osteogenic islands and their fusion, alveolar processes are formed. 3. During the 9-10th weeks of intrauterine development, the primary palate is formed as a result of the fusion of the palatine processes. 4. At the 11th week of intrauterine development, the bone base models both jaws. Due to the processes of histogenesis of the soft tissues of the maxillofacial apparatus, the face acquires anthropomorphic definitive human features.
Morphometric and topographic-anatomical features of the suprahyoid triangle of the anterior cervical region in the fetal period of human ontogenesis. Higher State Educational Establishment of Ukraine «Bukovinian State Medical University», Chernivtsy, Ukraine.ABSTRACT. Background. The study of the features of spatio-temporal transformations and the variant anatomy of the suprahyoid region (SHR), the clarification of the critical periods of development and topography of its structures in the fet al period of intrauterine development (IUD) is an important area of morphological research, the development of which contributes to the improvement of methods of prevention, early diagnosis and effective correction of congenital malformations and acquired diseases of the human neck and face. Objective. To find out the dynamics of morphometric and topographicanatomical changes of the suprahyoid triangle of the anterior cervical region in human fetuses. Methods. 61 specimens of human fetuses 160.0-480.0 mm of parieto-coccygeal length (TCD) (4-10 months of VUR) were investigated, among which 34 were male and 27 were female. A set of methods of morphological research was applied, which included anthropometry, morphometry, X-ray techniques, preparation, three-dimensional reconstruction, statistical analysis. Results. It was found that the anterior angle of SHR in males decreases slightly during the fetal period of IUD, except for dolichomorphic objects, which tend to increase from the middle of the fetal period, while in femalesalmost unchanged in mesomorphic objects. In mesomorphic males and dolichomorphic females, the anterior angle of the SHR decreases at 7th month of IUD, while in brachymorphic females it increases. The length of the lateral and posterior borders, anterior-posterior length and area of SHR tend to decrease in male brachymorphic fetuses. In dolichomorphic female fetuses, it decreases by the 6th month of IUD with subsequent growth by the end of the fetal period of development. Irregular temporal dynamics of changes in these morphometric parameters of SHR is observed in dolichomorphic male fetuses and in brachymorphic female fetuses, where accelerated growth was detected in the 6th month of IUD and slowed down during the 7th month of development. Conclusion. The critical periods of morphogenesis of the SHR of human fetusesthe time of the change in the growth rate of the region depending on gender and constitutional typeare 6-7 months of IUD, which may indicate the formation of variants of the structure during this period, and the possible occurrence of congenital defects of the neck and maxillofacial region.
The aim: To find out the sources of origin, the chronology of ossification, the peculiarities of age-related topographical and anatomical changes in the bones of the human orbit. Materials and methods: The research was carried out on the specimens of 18 human embryos and prefetuses aged from 4th to 12th weeks of intrauterine development and 12 human fetuses aged from 4th to 9th months which were studied by microscopic examination and 3D reconstruction. Results: The first signs of osteogenesis around the main nervous and visceral contents of the orbit rudiment are observed in 6-week-old embryos in the form of seven cartilaginous bone models. The first signs of ossification in the region of the orbit are found in the maxilla. During the 6th month of intrauterine development, intensive processes of ossification of the frontal, sphenoidal, ethmoidal bones and maxilla are noticeable. From the beginning of the fetal pe¬riod of human ontogenesis, the ossification of bone rudiments that form the walls of the orbit continues. The processes of ossification of the structures of the sphenoidal bone continue, which leads to morphological transformations of the orbit in 5-month-old fetuses – it is separated from the sphenopalatine and infratemporal fossae by a bone layer, the optic canal is formed, and in 6-month-old fetuses, processes of ossification of the frontal, sphenoidal and ethmoidal bones and maxilla occur, Müller’s muscle changes its structure to a fibrous one. Conclusions: Critical periods of the orbit development are the 6th month of prenatal ontogenesis and the 8th month.
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