[Characteristics of the structure and functional potentials of the metaepiphysis of tubular bones]

During early postnatal ontogenesis in the metaepiphyseal plate of the developing rat tibial bone, the borderline zone, the columnar cartilage zone and the zone of macrovesiculous cells differ in their cell composition, structure of basic substance and in functional and reactive potencies, which manifest themselves most distinctly after injection of growth-promoting hormones to the animals. The organic specificity of the metaepiphyseal borderline zone depends, first of all, on its intermediate position between the cartilage, fulfilling further bone growth lengthwise as an organ, and a developing endochondral bone substituting cartilage in the epiphysis. The borderline zone retains these features under hormonal effect. In the zone of columnar cells, it is reasonable to distinguish a layer of cuboidal cells--mature chondrocytes posessing great reactive and reparative possibilities, which become especially distincitive after prednisolon and TCT injection.