Histopathology of the intervertebral disc of progressive ankylosis mice.

The intervertebral disks of progressive ankylosis mice were examined at successive periods in order to describe the pathologic lesions involved and to explore possible relationships with any known human disorder. The techniques employed in this study showed the presence of necrotic foci of calcification that ultimately obliterated the anulus fibrosus. Following the appearance of these lesions, peripheral proliferation of hyaline cartilage appeared that eventually bridged adjacent vertebral bodies, calcified, and was replaced with bone. The results of this study support the hypothesis that the progressive ankylosis mouse has a disorder affecting mineralization. Although it does not exactly resemble any known human disorder, it should be an important model for studying both crystal deposition and abnormal mineralization of hyaline cartilage and fibrocartilage since many vertebral ankylosis disorders, as well as the normal aging process, involve increased mineralization.