[Formation of adaptive structures at tendon compression sites]

The structure of tendons in long and short human fibular muscles, in superficial and deep toe flexors of the dog hind paws has been studied histologically and histochemically. In the parts of tendons experienced pressing down, various degree of tendinous transformation into cartilaginous and osseous tissue has been revealed. The degree of transformation depends on the power of pressing factor and on the age of the individual. In the course of adaptive changes in these parts certain constructions appear that are oriented transversally to the tendinous fasciculi, but along the pressing vector and having the appearance of basophilic "cross-bars" and oxyphilic "columns". These constructions contain acidic mucopolysaccharides (glycosaminoglycans) of chondroitinsulfates of A, B, C types and keratansulfate. In the course of reconstruction of cartilaginous tissue into the osseous, avascular tissue transforms into the tissue rich in blood vessels.