不同月龄虹鳟肝显微及超微结构特征

应用多种组织化学方法和透射电镜技术，对同一生长条件下8月龄、20月龄及30月龄虹鳟（Oncorhynchus mykiss）肝显微结构和超微结构特征进行研究。结果表明：不同月龄虹鳟肝被膜均为单层扁平上皮，厚度变化明显；肝细胞为单核，8月龄细胞排列不明显，20月龄及30月龄形成完整双层管式排列，胆管及其周围结缔组织随月龄发育尤为明显，血窦分支吻合成网状，窦壁内皮细胞扁平，胞质孔较多，窦腔内巨噬细胞具有典型胞质突，但并没有观察到Kupffer细胞；各月龄组肝星状细胞发育完善，胞突彼此相连；汇管区分为胆管孤管型、胆管动脉型、胆管静脉型、胆管动静脉型4种，8月龄以胆管孤管型为主，20月龄以胆管动脉型为主，30月龄以胆管动脉型、胆管动脉静脉型为主。因此，性成熟前虹鳟肝组织结构与其生理发育密切相关，胆管系统结构形式随月龄变化明显，肝细胞排列逐渐完善，Disse间隙胶原纤维及网状纤维含量逐渐增加，与被膜、中央静脉及汇管区结缔组织互相延伸，构成肝完整骨架，有利于调节肝细胞正常生理功能。

Microstructure and Ultrastructure of the Liver Tissue in Oncorhynchus mykiss at Different Ages

The liver microstructure and ultrastructure of 8-month-old, 20-month-old and 30-month-old Oncorhynchus mykiss were observed by both light and electron microscopy. The results showed that the hepatic capsule thickness varied with age. The parenchyma showed tube-like arrangement of two-hepatocytic plates encircling central venous radially. The hepatocytic microvilli extended from hepatocytes into biliary passages and towards the space of Disse. The hepatic stellate cells (HSC) were located in the space of Disse with irregular shape and angular nuclei and rich in heterochromatin and paranuclear lipid droplets. Cytoplasmic processes radiated randomly from the cell body and round sinusoid. There were free ribosomes, rough endoplasmic reticulum, Golgi complex and mitochondria in the cytoplasm and cytoplasmic processes. There were macrophages in the sinusoid, but Kupffer cells were not evident in the liver. The stromal reticular fiber increased with age. HSC and sinusoid developed perfectly in all age groups. Vessels and bile ducts were observed to scatter without any apparent order within the parenchyma. The portal area was arranged as solitary biliary, biliary-arteriole, biliary-venous and venous-biliary-arteriolar tracts. Structural differences of the portal area between different ages were observed. It was mainly the biliary solitary tube at 8-month old, while there were mainly biliary-arteriole type at 20-month-old and venous-biliary-arteriolar type at 30-month-old. These results indicated that the liver structure varied with in O.mykiss.