著者

田島 正典

出版者

北海道大学

雑誌

獸醫學研究 (ISSN:04393457)

巻号頁・発行日

vol.1, pp.1-"64-6", 1953

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The severe prevalences of equine encephalomyelitis were observed in Hokkaido from summer to autumn, 1948 and 1950. The author has histologically investigated the central nervous system of 56 cases, which affected naturally with the malady during the prevalences. Materials examined are shown in Table 1. The summarized results obtained are as follows : (1) Grossly, characteristic changes in the central nervous system were scanty. As main findings, congestion, petechial hemorrhage and edema were observed in nervous substance and leptomeninges. There were formation of "Druckwulst (Occipital protrusion)" DEXLERs which were morphological change caused by presumably increasing cerebral pressure in 20 cases and necrotic and malactic focus in 1 each case respectively. (2) Histologic changes in the central nervous system of the entire number studied are comprehended under the diagnostic name of encephalomyelitis universalis and during the earlier stages of the disease exudative changes are prominent, but in the later stages proliferative processes take over gradually the former. (3) The total cases were classified, according to existence of tissue infiltration of polymorphonuclear leucocytes and its degree, into the three pathological stages; that is, leucocytic, transitional and nonleucocytic stages (Tables 2,3 and 4). There were the differences to a certain extent among the stages, not only the tissue infiltration of polymorphonuclear leucocytes but also in occurrence of other inframmatory reactions and its regional distribution. These stages are closely related to the length of the disease as shown in Table 6. Namely, such difference in the nature and the distribution of lesions, it should be ascribed to the time factor and it is further considered that the severity of the disease or the natural resistance of the individual horse play also a certain role. (4) Polymorphonuclear tissue infiltration were observed in 31 cases (55%). The majority of the cases (94%) were those which died or were destroyed within fifth day of the contracting disease. During the earlier stage of the disease, polymorphonuclear leucocytes infiltrated diffusely throughout the central nervous system and disappeared rapidly, then were replaced by proliferative processes especially by the proliferation of the microglia cells. (5) Perivascular cuffs were observed in the whole studied cases. It came to highest degree in third to fifth day of the disease and infiltrated cells overflowed frequently from ROBIN-VIRCHOW's spaces into the surrounding parenchyma. Cellular constituents in perivascular cuffs consisted of polymorphonuclear leucocytes, lymphocytes, lymphoid cells, lymphoblasts, macrophages, plasma cells and eosinophile cells. Its constitution made discrimination on each case, but as a rule, at the earlier stage numerous polymorphonuclear leucocytes were observed and accounted for approximately 50% of the total cells. Then cells of the lymphocytic series became gradually to main constituents. The former is apparently hematogenous and suggested that the majority of the latter should have arisen in that spot. (6) Mobilization of the neuroglia cells was very slight in the earlier stage of contracting disease, especially in the case that which showed heavy infiltration of polymorphonuclear leucocytes. When polymorphonuclear leucocytes tend to disappear, these are gradually replaced by both nodular formation and diffuse proliferation of glia cells. In all cases, microglia cells proliferated most activly and mobilization of oligodendroglia cells and astrocytes were slight. There was no proliferation of glia fibers. Rod shaped cells were observed in on and about fourth day of the disease, and as a rule, increased in number with progress of the disease. Apart from the malactic foci, gitter cells were seldom demonstrated. (7) Degeneration of the nerve cells was observed in the whole cases studied. Its degree ran usually parallel with the severity of other inflammatory c