According to the structure and function, the epithelium of gill filament is seperated into four zones: frontal ciliated columnar cells, lateral ciliated columnar cells, mucous cells and flat cells.

• 鳃丝上皮按结构与功能可区分为4个区带：前纤毛柱状细胞区、侧纤毛柱状细胞区、粘液细胞区和扁平细胞区。