Japanese Journal of Veterinary Research;Volume 19, Number 1-2

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PATHOLOGICAL STUDIES OF MAREK'S DISEASE : I THE HISTOPATHOLOGY ON FIELD CASES IN JAPAN

FUJIMOTO, Yutaka;NAKAGAWA, Michio;OKADA, Kosuke;OKADA, Masaaki;MATSUKAWA, Kiyoshi

Permalink : http://hdl.handle.net/2115/1969
JaLCDOI : 10.14943/jjvr.19.1-2.7

Abstract

In order to clarify the characteristics of Marek's disease, 181 cases of chickens were histopathologically investigated. They consisted of field cases which were considered as cases of classical (groups A, B & C) and acute Marek's disease (groups D, E & F) on the basis of clinical, epidemiological and pathological features. As a result of investigation, basically 2 kinds of lesions were found in the peripheral nerves : Tumorous proliferation (T-type) and non tumorous response (R-type). Therefore, each case consisted of any of 3 types (T, T+R, R). Furthermore, T-type lesions could be subdivided into 3 according to the types of cell which appeared and the characteristics of the lesions. T_I-type lesions consisted of only uniform small lymphoid cells. T_<II>-type lesions consisted of pleomorphic cells which included small, medium and large lymphoid cells (lymphoblastic and hemocytoblastic) and fewer reticulum cells. T_<III>-type lesions consisted of reticular or undifferentiated mesenchymal cells. R-type lesions of small lymphocytic and plasma cellular infiltration and were accompanied by frequent edema and proliferation of Schwann cells. Tumorous proliferation was often found in the visceral organs and tissues, and the central nervous system. The cells of which they were composed were similar to those of the peripheral nerves (T_I, T_<II>, T_<III>). Tumorous invasion was found extending from the nerve fibers in the visceral organs and tissues to the adjoining tissues in some places. Eye lesions were considered as one kind of lesion in systemic tumorous proliferation. All investigated groups were regarded as one disease entity with lesions possessing the same characteristics, but of varying severity. Consequently, it may be considered that Marek's disease is closely connected with the nerve tissues and the lesions mainly consisted of tumorous proliferation of lymphoreticular cells originating from the undifferentiated mesenchymal tissues of the extracapillary reticular tissues in the whole body.

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