The mechanism of regeneration of the tissue of the chest on the example of needle ether

The article presents the results of a microstructural study of the regenerating tissues of the thoracic limb of the needle-shaped newt after total resection, taking into account the histological and histochemical features, and also considers the timing and mechanism of the formation of various tissue structures: cartilage matrix, muscle tissue and skin. The studies were carried out in the histological laboratory of the Department of Anatomy, Pathological Anatomy and Surgery of the Institute of Applied Biotechnology and Veterinary Medicine of the Krasnoyarsk State Agrarian University in 2021. The sections prepared on a microtome were stained with hematoxylin and eosin, using the Van Gieson method, Mallory and Schiff's alcian blue. The sections were examined under a Mikomed-5 binocular microscope and microphotography was performed with a Canon PC 1201 camera. It was found that on the 62nd day after amputation of the triton's thoracic limb, the formation of the main anatomical structures of the regenerating limb is completed: the humerus, the bones of the forearm, wrist, metacarpus and fingers. Regeneration of the limb is due to a number of regularities: the division of cells of the fibroblastic row, oriented in the direction of growth of the regenerate, then the formation of a matrix of light-optically dense tissue around them and the formation of a zone of cartilaginous tissue in the area of articular surfaces. A feature of post-traumatic histogenesis of cartilaginous bone in newts after total amputation of the thoracic limb is the sequential formation of cartilaginous bone structures followed by morphofunctional maturation of chondrocytes and matrix.At the same time, the development of striated muscles, covered with thin skin with 3–6 layers of multilayer non-keratinizing epithelium and with functionally active glands and functionally active glands, occurs, which determines the definitive development of the newt limb. On the 62^nd day of regeneration in the proximal parts of the metacarpal bones in the chondromucoid, acidic mucopolysaccharides detected by the Schiff method with alcian blue are determined. Such morphological and histochemical differentiation indicates that first the morphological (structural) matrix of the cartilaginous bone is formed, and later the amorphous substance is saturated with acidic mucopolysaccharides, which determine the morphofunctional maturity of chondrocytes and chondromucoid in the regenerating bones of the newt limb.