Characteristics of the Intestine of Infantile Mice with Reference to the Pathogeny of Experimental Cholera

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In the pathogenesis of infectious diseases, a certain host factor should play a significant role as well as a pathogenic microorganism. Cholera, an infection with Vibrio cholerae, is not an exception. The clinical manifestation of cholera should be influenced by a certain condition of the host infected with Vibrio cholerae. In the experimental cholera of mice by oral challenge with Vibrio cholerae which has been developed by Ujiie and others, the incidence of the disease is closely related to the age of mice; only infantile mice younger than one week old of age are susceptible to oral challenge with Vibrio cholerae, and in mice older than one month, neither symptom nor multiplication of Vibrio cholerae in the intestine is seen. Therefore, it is understood that the infancy of mice should be one of the host factors as far as the experimental cholera in mice is concerned. It is presumed that characteristics of the infancy of mice may consist of uncompleted intestinal flora, deficiency of digestive enzymes, simplicity of intestinal content, particular immunological condition, abnormal absorptive ability of the intestine, etc. In this study, the morphological structure, histochemical behavior and function of the intestinal mucosa were investigated to compare the differences between infantile and adolescent mice. The characteristics of the infancy were as follows. 1). The surface of villi was lacking in enzyme layer. 2). The intercellular space in the epithelium was wide and conjunction between the cells is lax except apical region. 3). There were a lot of vesicles and vacuoles of various size or phagosomes and pinocytotic indentations in the upper part of the absorptive cells. 4). A large number of phagolysosomes were found in the middle part of the cytoplasm. 5). The plasma membrane of microvilli was lacking in trilaminal structure. 6). Polysaccharides and alkaline phosphatase were not or poorly found in the brush border. 7). Epithelial cells ingest protein (ferritin) without decomposition. The above mentioned characteristics which were found in the infantile mice suggest that toxin or toxin-like substances produced in the intestine by multiplying Vibrio cholerae will be able to be absorbed through the intestinal wall. So far, no exact knowledge on the host factor in human cholera has been obtained. However, it can be presumed that some of the factors which were indicated by the present study may be a homologous condition in the pathogeny of human cholera.感染症において,病原体が病因として決定的な役割を演ずるのは当然であるが,同時に宿主側の条件が発症機序に大きく関与する.コレラについても例外ではなく,感染個体の発症如何は宿主生体側の条件に左右されるとが大きい.氏家らが開発した幼若マウスにおける実験コレラでは,コレラ菌経口感染による発症率が,生後日数と確実に相関する.すなわち,生後1週間頃を境として発症率が著明に異なり,生後1ケ月以後のものでは全く発症が認められない.この実験コレラの成績に関しては,マウスの幼若性を発症のための宿主側条件の一つとして理解することが出来る.実験コレラ発症要因としての幼若性を分析すれば,腸内細菌叢の未完成,消化酵素の欠如,腸内容の単純性さらに免疫の異常などとともに腸粘膜細胞の構造ならびに機能の未熟さを挙げることが出きよう.この研究においては,腸粘膜の構造および機能を,生后1週間前後ならびに1カ月前後のマウスについて比較し,幼若性という特質を両者の相異からみいだそうと試みた.幼若マウスに認められた特徴は次のようであった.1,絨毛上皮の表面はenzyme layerを欠いている.2,絨毛上皮層の細胞間隙が広く,細胞間の結合が弱い.3,細胞質内には大小多数の空胞,液胞あるいはPhagosomeを有し,同時に多数のpinocytotic identationを認める.4.細胞質内には極めて多数のPhagolysosomeが存在する.5.Microvilliにおいては,限界膜の三層構造が不明瞭である.6.刷子縁における多糖類の存在およびアルカリフォスファターゼの活性は極めて乏しい.7.上皮細胞は蛋白質(フェリチン)を未消化(原形)のままとり込む.以上のように,幼若マウスが示した腸膜粘の構造ならびに機能上の特異性は,腸管内においてコレラ菌が増殖した場合,その毒素または毒素様物質が容易に吸収される可能性を示している.ヒトにおけるコレラ発症の生体側要因は今日全く不明であるが,ここに幼若性を分析して得たいくつかの条件の個々あるいはそのいくつかが重さなり合って,ヒトのコレラ発症に相似の条件を呈供することもありうると思われる.
長崎大学熱帯医学研究所,Institute of Tropical Medicine, Nagasaki Universityの論文

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岩永正明
Ddepartment Of Bacteriology Faculty Of Medicine University Of The Ryokyus

Characteristics of the Intestine of Infantile Mice with Reference to the Pathogeny of Experimental Cholera

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