Abstract

Objective: Morphological and descriptive analysis on different features of ultrastructural lumbar intervertebral discs during physiological and pathological conditions.

Design: This study was conducted on 33 anatomical preparations of L4-L5 and L5-S1 from cadavers, classified between normal and pathological according to Rolander criteria, and subsequently analysed by using scanning electron microscopy (SEM) technique.

Results: 7 out of 33 discs were classified as normal and 26 as pathological; SEM analysis showed a lamellar structure made of collagen fibres arranged as concentric bundles connected by annulus fibrosus cross-bridges, while the nucleus pulposus appeared as if consisting of a fibril substance arranged on an irregular pattern to form a sort of weave formed by softer fibres. Conversely, degenerative processes in pathological discs may be identified as fissures, especially through a radial arrangement from the third internal to the middle one in the annulus. Discs classified as normal showed microfissures especially on the external wall of the annulus.

Conclusion: Based on our observations, external microfissures can be considered a result of disc physiological involution and are not related to any degenerative process affecting the disc, which are instead represented by circumferential and radial fissures located on the posterior region.

Keywords: Degenerative intervertebral disks; Electron probe microanalysis; Fibrillar collagen; Annulus fibrosus