[Characteristics and structural variants of human lumbar intervertebral disks]

By means of macro- and microscopical methods structure of 412 lumbar intervertebral discs (ID), obtained from 84 corpses of persons died at the age 16-90 years have been studied, as well as 30 macerated lumbar vertebra. During these periods the lumbar ID are formed by hyalin laminae and a connective tissue wall, surrounding the cavity. According to the tissue type, in the ID wall three main layers are differentiated. The external layer is determined as a fibrous ring, the middle one--as fibrous-cartilagenous and the internal one--as a chondromucoid ring. The three layers gradually and consequently turn one into another. According to manifestation degree of these layers, development of the internal layer and size of the cavity three main variants of the ID structure are nominated: intervertebral synarthrosis, intervertebral hemiarthrosis and intervertebral "diathrosis" (real articulations have not been revealed between the vertebral bodies). The occurrence rate of the ID structural variants revealed in the lumbar part of the spinal cord is demonstrated. Absence of chordal mucous in the cavity is specific for the ID during the age periods investigated. The role of the "nucleus" is performed by the internal layer of the ID wall, which possesses a system of processes and a forming peculiar pulpous complex, which ensures the ID adaptation to various changes in position of the vertebral locomotor segment. The pulpous complex is surrounded with a united fibrillar carcass of hyalin laminae and fibrous-cartilagenous ring; together with the carcass it forms an elastic layer between the vertebral bodies.