膠原病観に基づく尿道細動脈の病変形態に関する実験的研究
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Previously, Tabayashi and Midorikawa in their studies on urethral stricture found degenerative changes of the walls of the arterioles located in the periurethral connective tissues showing proliferative or sclerocicatricial transformation. Since these changes are seen in all instances of uretheal stricture resulting from such causes as gonorrhea, trauma, tuberculosis or even by unknown etiology, these investigators regard such changes of the vascular wall to be common to all histologic characteristics of urethral stricture. Among the stricture due to unknown etiology, there are cases of habitual urticaria and of operations on duodenol stricture. There seems to be a relationship between the connective tissue changes and the degeneration Of the vascular walls, and, from the standpoint of collagen diseases, Tabayashi and Yamamoto made pathologic observations on the finer artetioles and their tissue beds. The results disclosed that the cases showing proliferative or degenerative changes of the walls of peripheral vessels, or so-called vasculitis type, comprised 62.5%, those demonstrating sclerotic transformation 12.5% and those with hypertropic changes 15.0%. The pathologic findings in the vasculitis type are characterized by centripetal, marginal or Obstructive changes of the lumen, although asthenic or patent forms may occasionally be seen. The intima shows often a marked hypertrophy due to fibrotic or proliferative changes as well as to cicatirization, resulting in luminal narrowing. The changes of the media are usually those of degeneration in varying degrees. Cellular infiltrations are chiefly of small round cell type, either aggregated around the vessles or widely scattered. On the basis of the above findings, which these authors interpreted to consist basically of so-called fibrinoid transformation, the condition was included in the category of collagenosis. Many reports are already found in the literature on the experimental investigations on allergic and rheumatic changes. The author, following the experimental method of Prof, Otaka, has undertaken animal experiments for the purpose of ascertaining whether or not these changes really belong to the category of collagen diseases. It must be emphasized that it is of utmost importance to determine if the pathogenesis of urethral stricture is related in any way to allergy. The experimental method consisted of producing urethral stricture by making strictureinducing injectioes in animals repeatedly sensitized with stated amounts of horse serum, egg albumin and 7-globulin. The animals were then sacrificed at varying intervals of time and histological sections were prepared from the tissues corresponding to the pars membranacea bulbi of the human. Observations were made by staining the sections by the same method employed by Tabayashi-Yamamoto. The results of observation may be summarized as follows: 1. So-called fibrinoid changes in the tissue beds consist of the swelling and loosening of connective tissue, the disruption, irregular arrangement and poor H・E, stainbility of fibrils. accompanied by cellular infiltrations. 2. The proliferative and degenerative changes of the walls of small vessels are particularly remarkable. 3. The changes of the vessel intima consist chiefly of proliferative hypertrophy, but: occasionally of expansive swelling. As a result, the lumen is either narrowed or obstructed in varying manners and stagnation of erythrocytes and plasma may be seen. 4. The smooth muscle fibers of the media are often swollen and separated or their arrangement may be distorted, and when these changes are extreme partial lysis or even total disappearance may occur. 5. The specimens vary as to the extent of cellular infiltrations, the two most usual types being aggregation and diffusion, which may be either compact or loose. These findings in animals present certain points of close resemblance to those seen in man, although there are naturally some differences in the following respects: In experimental specimens the changes of the connective tissue beds are frequently noted to be of recent origin, where as in human materials, atlhouth relatively typical fibrinoid changes are found in a few instances, the majority show proliferative or sclero-cicatricial changes of the connective tissue. The changes in the walls of the small vessels closely resemble each other, consisting of the narrowing of the lumina, proliferative hypertrophy of the intima, the swelling, separation, distorted arrangement and lysis of the medial fibers. In human materials, however, some restorative processes are evident, associated with distorted arrangement with cicatricization or mild hypertrophy. Cellular infiltrations are usually typical in experimental specimens but in human materials they are generally either mild or atypical. The points of difference in the findings between the two kinds of specimens may be briefly summarized. In human materials the so-called sclerotic type was represented by 12.5% and the medial hypertrophy by 15.0%, but in experimental specimens no such changes were found. Likewise. there were no animal specimens showing marked proliferation or cicatrization of the perivascular connective tissue. Even in experimental materials, the findings were different according to the period of observation, some having been prepared after one day, 7-8 days or even 1-2 months and those having received repeated injections into the urethra. Moreover, the changes were more recent and appeared to be fresh, as compared with the lesions existing for many years as in human cases. To summarize briefly, although there are some differences in the picture of fibrinoid changes in the arterioles and their connective tissue beds between the materials obtained from cases of urethral stricture in man and those of animals used in the present sensitization experiments, the histological findings in both groups resemble each other very closely. These observations, lead to the conclusion that certain factors simulating those involved in collagenosis are operative; in the pathogensis of urethral stricture.
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