IMPBESSIONS PROI}UCED BY ITISC HERNIATIONS ON TIIE BOI}IES OF HT]MAN VER.TEBBAE

It is a common exPerience in medical practice that lesions of the intervertebral discs may be respon'sible for many cases of low backpain. The first detailed description of herniations of disc material into the spongiosa of adjacent vertebral
bodies (schmorl's bodies) was given by Schmorl (192?). A defect in the plate of cartilage present on either
surface of the intervertebral disc was considered responsible for such herniation. This view was confirmed experimentally where disc herniations were produced in dogs after making surgical damage in the cartitage plates covering the discs
(Compere and Keyes, 1933). Cases of disc prolaPse into the adiacent vertebral bodies were rel)orted in children who showed congenital defects in the cartilage Plates (Schmorl, 1930). A degenerative tr)rocess was also assumed to be an  underlying factor since many cases of Schmorl's bodies have also been ohserved in old subjects. In senilespecimens, these ProlaPses were found flrm in consistencY due to calcium deposition and in some ca' ses they were surrounded bY a r+ astive shell of sclerosed bone that could be visualised on X-raY examination (CoventrY, 1945)-The previotrs investigations on Schmorl's bodies were carried out using histological and radiological means but as far as our knowledge gces, no detailed study of their tra' cemarks on dried vertebrae has been done. The main objective of the present
work is to describe the shape, course and distribution of their impressions as seen in dried specimens.