鶏の唾液腺細胞の超微細構造について

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　光顕的組織化学によって類別されている鶏唾液腺の粘液細胞と漿･粘液細胞との差異を電顕的に観察した. 粘液細胞の観察用としては前下顎腺を用い,漿･粘液細胞の観察用として前舌腺,単孔上顎腺および口角腺を用いた. 白色レグホーン種7羽からそれぞれの唾液腺を採取し, 直ちにその細片をs-Collidineで緩衝した1%オスミック酸(pH7.4)で2～3時間固定したのち, Luft法によりエポキシ樹脂で包埋. 超薄切片をつくり, これに酢酸ウランと硝酸鉛の二重染色を施したものを日立HU-11,D-S型電子顕微鏡で観察した.　粘液細胞は分泌顆粒が充満して固有の細胞質は極度に少なく,核は細胞基底部に押しやられている. 分泌顆粒内には微細粒子がまばらな電子密度の低い部分と微細粒子が集合した電子密度の高い部分とがみられ,後者は分泌顆粒の限界膜に沿ってその分布域が半月状をなして見える.個々の分泌顆粒は分泌直前まで限界膜によって包まれ,互いに融合することは少ない.　漿･粘液細胞にも分泌顆粒が充満するが, この細胞は顆粒間や細胞基底部にかなり多くの固有細胞質を保有し,核は基底上部に位置する. 分泌顆粒内には電子密度の低い部分と高い部分とが認められ,特に後者の形状は腺によって多少の違いがある.すなわち,顆粒内の電子密な部分は,前舌腺と単孔上顎腺の細胞では顆粒の限界膜から遊離して小塊状をなし, 口角腺の細胞では限界膜に沿った顆粒周辺部にリング状をなして存在する.個々の分泌顆粒は限界膜を失なって互いに融合するものが多く, なかにはその程度が進んで融解に近い状態を示すものもある.漿･粘液細胞にはこのほか叉状の糸粒体, 同心円状の滑面小胞体および細胞相互の複雑な接触面等が観察されるが, チモーゲン顆粒は認められない.　粘液細胞も漿･粘液細胞も分泌顆粒はゴルジ装置と密接な関係をもって形成され, またいったん形成された分泌顆粒に粗面小胞体が直接連絡開口し, その内容物が流入して顆粒が増大する可能性が強い.これらの分泌顆粒は両種細胞とも黒住の述べるIV型(従来のeccrine型)によって細胞外に放出される.The morphological differences between mucous cells and sero-mucous cells of chicken salivary glands which have been classified histochemicaly were examined with the electron microscope. The anterior submandibular glands were used for observations of the mucous cells and the anterior lingual, maxillary and angularis oris glands for the sero-mucous cells. Each salivary gland from 7 White Leghorn chicks was fixed in ice-cold 1 % OsO_4 solution buffered with s-Collidine at pH 7.4. After 2-3 hours of fixation, the tissue blocks were embedded in Epon according to the method of Luft ('61). Ultrathin sections were double stained with uranyl acetate and lead citrate, and were examined with a Hitachi HU-11, D-S electron microscope. As the mucous cells are filled with a large number of secreting granules, only a small amount of cytoplasm is present and the nucleus is located at the basal portion of the cell. A part of low elctreon density in which fine granules are dispersed and a part of high electron density in which fine granules are aggregated can be observed in the secreting granule and the latter are aggregated in a semilunar-shaped mass at one side along the limiting membrane. All of the secreting granules are enveloped by limiting membranes and there is almost no mutual fusion until just before their discharge. The sero-mucous cells are also filled with secreting granules but the large amounts of cytoplasm are seen in its basal part and amoung the granules compared with the mucous cells. The secreting granule also has a low electron density part and a high density part but the form of the latter differs somewhat according to the variety of the glands. That is, the part of high electron density in the granules in the anterior lingual and maxillary glands is in the form of a small mass and is free from the limiting membrane but in the angularis oris glands, it is present in ring form along the limiting membrane. Most of the secreting granules lose their limiting membranes and in some cases, fuse with each other. Besides the above, forked mitochondria, concentric arrays of smooth surfaced endoplasmic reticulum complicated intercellular junctions can be observed in sero-mucous cells but zymogen granule cannot be observed. The secreting granules of all cell types are formed in connection with the Golgi apparatus. Moreover, continuity of the rough surfaced endoplasmic reticulum to the secreting granules formed beforehand can be observed and its content flows into the latter to enlarge the granules. The discharge mechanism of mucous granules from both cell bodies is the Kurosumi's type IV extrusion (the previous eccrine mechanism).
宮崎大学農学部の論文

鶏の唾液腺細胞の超微細構造について

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