Background: Fibronectin, a large dimeric plasma glycoprotein found only in vertebrates, is a core
component of several extracellular matrices. Integrin receptors regulate different cell activities. Fibronectin expression
patterns in intervertebral disc have not been extensively studied. The aim of this study was to evaluate the distribution of
fibronectin in the different regions of the intervertebral disc, and in intervertebral discs of different levels of monkeys.
Methods: Spines of nine 3-4 year-old cynomolgus monkeys (Macaca fascicularis) were studied. From every spine, 5 vertebral
motion segments were sectioned (C5-C6, T3-T4, T9-T10, L2-L3, L4-L5) producing forty-five vertebral motion
segments. These were bisected in the sagittal plane. Immunohistochemical studies were performed using specific antibodies
to detect fibronectin. Results: A positive immunoreaction for fibronectin was found in the endplates, in the peripheral
annulus fibrosus, and in the longitudinal ligaments. There was no fibronectin immunoreactivity in the nucleus pulposus
and in the central annular region close to the nucleus pulposus. There were no differences in immunoreactivity to fibronectin
among discs of different levels and discs of different monkeys. Conclusions: Fibronectin may exert a role in the
organization of the extracellular matrix of the intervertebral discs. Identifying the structural features of the intervertebral
disc extracellular matrix may help to understand the mechanisms of intervertebral disc pathology.