Comparative histological study of human adult cervical and lumbar intervertebral discs and its relation to functions and diseases

Background The intervertebral discs are the major structural links between adjacent vertebrae. They serve to allow greater movement and compression between vertebral bodies. However, there is regional difference in disc structure and pathology relative to different mechanical stresses and load bearing. Aim of work Comparing the histological structure of human cervical and lumbar intervertebral discs at adult age to analyze the extent of variations in structure between these regions and its relation to their functions and diseases. Materials and methods (12) IVDs: (4) C3C4, (4) L4L5 and (4) L5S1 and adjacent bony vertebrae were removed from each of 12 adult male and female humans at autopsy. The discs and vertebrae were processed for paraffin sections and stained by haematoxylin and eosin, trichrome, orcein and safranin stains. Histomorphometric study and statistical analysis were conducted. Results L4-L5, L5-S1 IVDs presented less collagen and more elastic fibers in posterior region of annulus fibrosus than anterior region, peripheral regions were thicker than central one of lumbar end plate. The annulus fibrosus invading nucleus pulposus and dividing it but at cervical level invading without dividing it. Safranin reaction was positive and much higher in cervical than in lumbar annulus fibrosus. The reaction was much higher in lumbar than in cervical nucleus pulposus. There are significant differences in collagen, elastic fibers and heights of cervical and lumbar discs. Conclusion There are histological differences of human adult intervertebral discs in cervical and lumber regions which may affect their mechanical and physiologic functions and provide a better understanding of the external factors causing spinal disorders and enable the best method to be applied to the patients both at the diagnosis and the treatment stage.