ウマバエ属幼虫寄生馬の胃および十二指腸の病理学的所見

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Pathological detection was carried on Pars proventricularis where Gasterophilus intestinalis larvae used to live upon, and on Pars pylorics and the beginning of duodenum where G. nasalis larvae used to live upon (either of them being dense parasitic area), thus obtained the following. 1) At Pars proventricularis pustule-like protuberances were formed and on top of them crater-like parasitic perforations were observed. The parasitic perforation was about 1. 3-1. 8mm in diameter, the depth of which was just sufficient to inject the head of a worm (1. 5-2. 0mm). In the dense area with worms parasitic perforations were distributed at a rate of 4-5 per 1cm2. Mucousal layer of the protuberance indicated hypertrophy, and submucosa showed hyperplasia being very stiff. When many of parasitic perforations gather at the part of Margo plicatus, plicae of Margo plicatus became hypertrophied like papillae (papillomatous ploriferation). A parasitic perforation after a worm fallen off (i. e. parasitic traces) generally became shallower. 2) Formation of ulcer at the parasitic perforation was found by the microscopical detection. That is, the epithelial layer fallen off and disappeard completely exposing at the bottom the connective tissue layer (Lamina propria mucosae). Epithelium around the parasitic perforation indicated parakeratosis and specific degeneration was seen on prickle cells layer. Furthermore thin necrotic layer of the part, neutrophil infilltration and bacterial mass were interpositioned between the worm and exposed part of connective tissue. Exposed part of the above showed remarkable hyperplasia of granulation tissue (connective tissue), and various degrees of infiltration were observed on lymphocyte, plasma cell, neutrophil, eosinophil and mononuclear cell ; especially eosinophil infiltration was widely spread out to fairly apart section (Lamina propria mucosae). Muscular tunic of the mucous membrane directly under parasitic perforation was disjunctive and bandle of muscular fiber was branched in pieces with irregular courses and finally disappeared. Submucosa indicated remarkable hyperplasia too, with infiltration of eosinophil, etc. Furthermore connective tissue at the part indicated edematous swelling, showing remarkable change (edematous dissociation of wall, partly disjunction, etc.) of blood vessels (especially arteries). No remarkable change was observed on muscular layer and serosa. 3) At Pars pylorica and the beginning of duodenum, suckerform excavations (parasitic sulcus) were shaped. Diameter of margin of parasitic sulcus was about 5mm. At the bottom there was a hole of about 1. 5mm in diameter, in which a worm inserted its head. Some were showing 2-3 perforations in one parasitic sulcus. Inside of parasitic sulcus was sloped rather gently, but sometimes margin was abraded down being very shallow. (Most of the parasitic traces showed such tendency.) When parasitic sulcus gathered in large numbers, being pressed with each other, their typical shape (sucker form) changed into complicated irregularities. At parasitic region (specially at the beginnig of duodenum), mucosal plicae disappeared and generally projected compared with non-parasitic region. Mucousal layer and submcousal layer of parasitic region became stiffer remarkably being thicker. Furthermore by a lager number of worms being parasitic on duodenum, it strictured remarkably. 4) Under the microscope it was found that at parasitic sulcus mucousal layer was perfectly deciduated by abrasion exposing submucosa, thus forming ulcer. Narrow necrotic layer, foci of karyorrhexis of neutrophil, eosinophil, etc., were observed between the exposed part and the worm. At submucosa of the exposed part granulation tissue (connective tissue) proliferated, and various grades of infiltration were observed on lymphocyte, plasma cell, neutrophil, eosionphil and mononuclear cell. Mucousal epithtlium at margin of parasitic sulcus was partly collapsed and glandular tissue became atrophied. At the part followed, activation of epithelial cells accelerated secretion of goblett cells were observed. At the place fairly apart from parasitic sulcus (Lamina propria mucosae), too, infiltration of eosinophil, plasma cell as well as sweling of lymphatic follicles were observed. At the bottom of parasitic sulcus muscular tunic of the mucous membrane was disjunctive and disappeared being connected directly to thickened focus of submucosa. A part of those thickened submucosa indicated hyaline degeneration and edematous swelling. Arteries in submucosa indicated remarkable edematous dissociation of vessel wall (swelling). At muscular layer, too, interstitial tissue became lightly hyperplastic and somewhat eosinophil infiltration was observed. Furthermore lesion at Pars pylorica and duodenum were fairly remarkable in general compared with those at Pars proventricularis. It can be concluded that lesion of this disease is an inflammatory change (degeneration, exudation, tissue proliferation, etc.) based on mechanical and chemical activities of worms. At the same time histological presentation of allergy was also recognized.　G. intestinalis幼虫の寄生する馬の前胃部,並びにG. nasalis幼虫寄生の幽門部･十二指腸起始部の病理学的所見の検討を行なったが,双方とも病変の基本は同じである. すなわち,虫体による鈎着･穿刺などの器械的作用および虫体から出すある種の成分によると思われる化学的作用で,潰瘍形成および炎性変化(組織変性･滲出･組織増殖)が起こり,更に虫体の成分ないし代謝産物による感作でアレルギー性を獲得し,それに基づく組織反応も認められる. 本症の病変は,一般的に牛の双口吸虫症などの場合と比較するとかなり著しい. なおG. intestinalisとG. nasalisの幼虫を比較すると,前者がひとまわり大きく,それに伴い器械的作用も一段強いと思われるが,生起する病変は前胃部よりも幽門部･十二指腸の方が顕著である. これは双方の粘膜の性状が異なることに基因するものであろう.

著者

芦沢広三
宮崎大学農学部家畜病理学教室

ウマバエ属幼虫寄生馬の胃および十二指腸の病理学的所見

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