A PATHOLOGICAL STUDY ON DEFORMATION OF THE VERTEBRAL COLUMN IN THE "SHORT-SPINE DOG"

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The four available "short-spine dogs" were investigated pathologically ; the results obtained may be summarized as follows. 1. The cartilaginous tissues in the vertebral column, in point of composition of the column, were quantitatively more abundant than those of normal dogs. In addition, the epiphyseal cartilaginous plates remained for a long period of time and especially cartilaginous fragments in the arcus vertebrae were recognized in all cases. These phenomena are suggesive of the probability that ossification of the vertebrae is feeble during the developmental process and also after birth. 2. The tissue debris of the chorda dorsalis in the spaces of the nuclei pulposi (n.p.) began to disappear during considerably early stages after birth, and the spaces of the n.p. were gradually invaded by low-differentiated cartilage cells of the perinuclear layer of the annulus fibrosus (a.f.) and were-entirely in some instances-occupied by the cartilaginous structures. On that occasion, even in the 5-year-old dog, there sometimes existed such n.p. as the replacing by cartilaginous tissues had not been perfectly occurred. 3. In the a.f., according to the progressive changes of the low-differentiated cartilage cells, the formation of many groups constituted of these cells was recognized. These cell groups were found chiefly in the interior but also in the peripheral portion of the a.f.; moreover, massive hyaline cartilaginous tissues were scatteringly found in the a.f. That is to say, in the a.f. pretty extensively low-differentiated and progressive changes were seen simultaneously. In addition to these changes, degeneration of cartilaginous tissues was recognized in various portions of the a.f. and especially, usually found in scattered portions of the cartilage cell groups. It may be understood that these pictures are highly significant in respect to the deformation of the vertebral coltumn in the developmental process and moreover, after birth. 4. In the parts of the a.f. constituted of fibrocartilaginous tissue, fish-bone patterned structures were irregular in some places due to the morphological abnormalities of the corpus vertebrae and degenerative changes of the cartilaginous tissue. 5. In the a.f. adjacent to the corpus vertebrae and in the cartilaginous plates adjacent to the corpus vertebrae which were seen on the central surfaces of the epiphysis of the corpus vertebrae and in the parts facing the central portions of bifidities of the corpus vertebrae, the loss of the calcified zones of cartilage was seen in some places, as a result of the degenerative changes of cartilaginous tissue principally, though occasionally, in having no relation to such changes. In the majority of the epiphyseal cartilaginous plates, foci of degeneration were recognized. It may be considered that these changes exert considerable interference in the growth of the corpus vertebrae. 6. In the a.f., free new-formed bone tissues and periostally new-formed bone tissues deposited in the corpus vertebrae were observed here and there. 7. In one place respectively in cases Nos. 1 and 4,fusion of a part of the corpus vertebrae and of the entire vertebrae was recognized. As to the embryological mechanism of these changes further investigation needs to be performed. 8. The areas of clefts of the arcus vertebrae and proc. spinosus were occupied by cartilaginous or fibrous or both ; in these cartilaginous tissues, pictures of degeneration were found. Furthermore, as shown in the vertebrae cervicales in case No. 3,there were bifidities of the arcus vertebrae which had been repaired with new-formed bone tissues. 9. In the articulationes intervertebralis, costovertebralis and sacro-iliaca, both degeneration of the articular cartilages and unification of the articular surfaces were observed in many of the joints. A picture of ossification was observable in the peripheral part of the unified articulatio intervertebralis between the os sacrum and the vertebrae coccygeae in case No. 1. It may be understood that in the joints of the vertebral column, degeneration of the articular cartilages and unification of the articular surfaces arise from mechanical factors and, sometimes, that osseous fusion occurs in these joints. 10. The relation between the changes of the ganglia spinalia and nerve bundles of the nervi spinales in the vertebral canal and the deformity of the vertebral column must be a subject for further research. 11. In the costo-chondral junctions foci of degeneration were found in all cases. In case No. 4,the dorsal ends of some costae were articulated with each other. Moreover, in these joints, there were degeneration of articular cartilages, unification of articular surfaces, formation of free new-formed bone tissue and periostal apposition of new bone tissue. It may be considered that the morphological abnormalities of the costae have occurred as secondary results of deformities of the vertebral column. 12. In the bones other than the vertebral column, costae, sternum and os coxae, and in the visceral organs, there was no finding directly related with deformation of the vertebral column. Thus, on the basis of the present pathological findings concerning the "short-spine dogs", the following conclusions may be drawn. It may be regarded that in the vertebral column, low differentiation, progressive changes and degeneration of cartilaginous tissue in the a.f. as well as low accomplishment of ossification occurred in the developmental process and after birth. It may be understood that these processes are principal causes of deformation of the vertebral column and that the morphological abnormalities of the arcus vertebrae and other portions can be induced secondarily.
北海道大学の論文

A PATHOLOGICAL STUDY ON DEFORMATION OF THE VERTEBRAL COLUMN IN THE "SHORT-SPINE DOG"

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