缢蛏消化盲囊的组织学与组织化学

Histological and histochemical studies on digestive diverticula of Sinonovacula constricta

运用光镜、透射电镜及组织化学方法研究了缢蛏消化盲囊的结构与功能。消化盲囊为复管泡状腺,以导管与胃腔相通。腺上皮由胚性细胞(E 细胞)、纤维细胞(F 细胞)、吸收细胞(R 细胞)和分泌细胞(B 细胞)组成,它们在分布位置、结构及功能等方面各有其特点:E-细胞主要存在于近端(与导管相连处),体积较小、核质比大,能分化为其它类型的腺细胞;F-细胞内含发达的粗面内质网和游离核糖体,功能是合成、分泌消化酶;R-细胞以脂肪滴和糖原粒的形式储存丰富的能量;B-细胞只见于远端,游离端具发达的微绒毛,内含大量的次级溶酶体和消化残体,有很强的吸收和细胞内消化功能;B 细胞和R 细胞消化脂类的能力较强。导管壁由单层短柱状纤毛细胞和丰富的粘液细胞构成,纤毛柱状细胞能合成、分泌消化酶。消化盲囊参与无机盐代谢。

The structure and function of the digestive diverticula of Sinonovacula constricta were studied using light and transmission electron microscopy and histochemical methods. The digestive diverticula is the type of compound tubuloacinar gland which communicates with the stomach by a system of ducts. The glandular epithelium is composed of four types of cells :embryo cell (Ecell),fibrillar cell(Fcell),resorptive cell(Rcell) and secretory cell(Bcell).These cells are different from each other in distribution, structure and function.Ecells are mostly located at the proximate position of tubules connecting the duct and the big nuclearcytoplasmic ratio shows that they may be involved in mitotic activity for production of other cell types which comprise the glandular epithelium. Fcells contain plenty of rough endoplasmic reticulum and free ribosome suggesting that they may synthesize and secrete digestive enzymes. Lipid and glycogen are abundant throughout Rcells suggesting that these cells are the sites of significant energy stores. Bcells distribute only in the distal end of alveoli and have their cytological features: congested microvilli on the free border,numerous secondary lysosome and residual body support the view that Bcells are capable of absorption and intracellular digestion of food. Bcells and Rcells have the strong function of digesting lipid. The duct is composed of simple ciliated columnar epithelium and abundant mucous cell, and the former can synthesize and secrete digestive enzymes. The digestive diverticula may also participate in the metabolism of inorganic salt.