Effect of methods of preservation on the arrangement of collagen fibrils in connective tissue matrices: an x-ray diffraction study of annulus fibrosus.

Samples of annulus fibrosus were dissected from the anterior of lumbar intervertebral discs from adult rabbits. X-ray diffraction was used to provide a measure of the distribution of collagen fibrils in each sample. The sample was then preserved and the experiment repeated twice. Three methods of preservation were used: (1) fixation in formol saline, (2) freezing, (3) freezing in liquid nitrogen. Frozen specimens were subsequently thawed. None of the three methods of preservation affected the distribution of collagen fibrils in the tissue significantly. However, fixation does cause the collagen molecules to become more closely packed within a fibril. The method of choice for preserving annulus fibrosus and, by implication, other connective tissue matrices for ultrastructural studies is discussed.