[Morphometric analysis of differentiation of skeletal muscle fibers of the maxillofacial region during the process of embryonic development].

The skeletal muscle tissue of the lip, tongue, soft palate and masticatory muscles have been morphometrically studied in 70 human fetuses (4-10-month-old). In the muscles mentioned decrease in the nuclear volume and in the nuclear-cytoplasmic ratio is observed. Increase of the muscle fibres in the area of transversal sections is especially intensive during last three months. The labial and glossal fibres reach the greatest thickness. On the 6th month and further, there is an essential difference in number of myons with nuclei in the transversal section of the tongue and lips, as compared with the masticatory muscle and soft palate. In 9-10-month-old fetuses the index on saturation of the glossal and labial muscle fasciculi with capillaries is much greater than that of the soft palate and the masticatory muscle. There exists a statistically important and rather high positive correlation between the area of transversal sections of the muscle fibres, the number of nuclei in them and the density of capillaries in the muscle fasciculi. The relation between histochemical profile of the muscles under investigation and the number of capillaries in them is discussed.