3种珍珠贝的外套膜小片外表皮细胞的超微结构

Ultrastructure of the outer epithelial cells in mantle pieces of 3 species of pearl oysters

用透射电子显微镜对合浦珠母贝（Ｐｉｎｃｔａｄａｆｕｃａｔａ）、大珠母贝（Ｐｉｎｃｔａｄａｍａｘｉｍａ）和企鹅珍珠贝（Ｐｔｅｒｉａｐｅｎｇｕｉｎ）的外套膜小片外表皮超微结构进行比较观察，发现都是单层柱状表皮，由３类细胞构成，即柱状表皮细胞、粘液细胞和嗜酸性粒分泌细胞。柱状表皮细胞是贝壳和珍珠组份的主要合成和转运者，据其结构和功能的差异可细分为Ａ、Ｂ、Ｃ３型。粘液细胞和嗜酸性粒分泌细胞呈杯状或不规则，体积巨大，细胞质稀少，核的形态亦不固定，前者的胞体全由电子透明泡占据，后者含有大量嗜酸性的电子稠密颗粒。这２类细胞的主要功能是参与物质转运，它们在邻近表皮的结缔组织中也有分布，可作变形运动穿越基膜进入上皮层。

Ultrastructure of the outer epithelial cells in the mantle piece of pearl oysters Pinctada fucada, Pinctada maxima and Pteria penguin was observed under a transmission electron microscope. The results show that epithelial cells consist of 3 types of cells which are columnar epithelial cell, mucous cell and acidophilic granular secretory cell. According to their differences in structures, the columnar epithelial cells can be further devided into 3 types of A, B and C. The mucous cell and acidophilic granular secretory cell have irregular or goblet shapes and large volumes in which there are few cytoplasm and nucleus with fixed shape. The mucous cell body is occupied by quantities of electron-transparent vesicles, while the later has abundant acidophilic electron-dense granules. Both kind of cells above also distribute in the connective tissues near the outer epithelium. They are constantly observed to migrate across the epithelium with amoeboid locomotion.