不同盐度驯化下施氏鲟幼鱼鳃泌氯细胞结构的变化

Structural changes of chloride cells in gills epithelia of juvenile Acipenser schrenckii acclimated to various salinities

采用光镜和透射电镜方法,研究了不同盐度驯化下施氏鲟幼鱼鳃中泌氯细胞的分布和结构特征。结果显示,在淡水中,施氏鲟幼鱼鳃中的泌氯细胞数量较少,且主要分布在近鳃小片基部,胞体与核均较大而明显,胞内含大量线粒体;泌氯细胞中有网管和囊管,但网管欠发达,囊管分布面积小,细胞表面有顶隐窝。表现为典型的淡水型泌氯细胞(freshwater-type chloride cells)特征。与淡水组相比,盐度10组鳃泌氯细胞的分布和结构变化均不明显,仅数量略有增加,胞体变大。幼鱼在盐度25海水中驯化65d,鳃丝和鳃小片上泌氯细胞数量明显增加,泌氯细胞集中分布在鳃小片基部;超微结构显示,细胞内线粒体数量明显增加,胞质中网管颇为发达,囊管丰富,顶隐窝扩大,表面有微绒毛,表现为α-型(-αsubtype)泌氯细胞特征。泌氯细胞具有分泌体内过多Na+、Cl-以及调节体液渗透平衡的功能,其数量和结构变化与幼鱼所处的高渗环境相适应。

Modifications in the chloride cells of the gill epithelia of juvenile Amur sturgeon （Acipenser schrenckii） in various salinities （0, 10, 25） were examined by light and transmission electron microscopy. In freshwater, a few Chloride cells were present on the base of lamellae and in the interlamellar region of the filament with undeveloped tubular network and vesicle-tubular as freshwater-type chloride cells. While in brackish water （salinity 10）, fish showed a little increase in the number and size of chloride cells. In contrast to freshwater specimem, seawater-acclimated （salinity 25） fish showed a marked increase in the number and size of chloride cells. On the lamellae of these fish, chloride cells were generally centralizing to the base of lamellae. Ultrastructural modifications included： presence of a more compact tubular network, a greater development vesicle-tubular and a enlarged apical crypt bearing some short microvilli as a-subtype chloride cells. The gill chloride cell, with increasing in the number and modifying structure, participate in extruding excess Na^＋ , Cl^- and adjusting osrnolality of body fluid in the hyperosmotic medium.