HISTOMORPHOMETRICAL AND IMMUNOHISTOCHEMICAL STUDY IN PRIMATES (MACACA FASCICULARIS) ON THE DIFFERENCES AMONG CERVICAL, THORACIC AND LUMBAR INTERVERTEBRAL DISCS

The aim of this study was to analyse the morphological differences of the intervertebral disc at different levels focusing in the endplate and the anchorage of the disc fibres to the vertebrae and the distribution pattern of collagen I and II. This study was conducted on 45 intervertebral discs from nine monkeys (Macaca fascicularis). All slices were processed for histological, histomorphometrical and immunohistochemical analysis. The endplate was formed, at all the levels, by 3 zones: a cartilaginous zone adjacent to the nucleus pulposus, an intermediate mineralised zone of cartilage and a growth cartilaginous zone adjacent to the vertebrae. The inner annular fibres anchored to the not mineralised cartilaginous endplate zone, whereas the outer annular fibres anchored to the mineralised cartilaginous endplate zone. The height of the intervertebral disc varied along the length of the spine. The smallest value was measured in T3–T4, with a larger increasing caudally than cranially. The highest value was measured in L2–L3. A cervical intervertebral disc was the 55% of a lumbar one. The findings of this study provide a detailed structural characterization of the IVD and may be useful for further investigations on the disc degeneration process.