日本沼虾消化道形态和组织学特点

HISTOLOGICAL AND SCANNING ELECTRON MICROSCOPIC CHARACTERISTICS OF THE DIGESTIVE TRACT OF FRESHWATER SHRIMP, MACROBRACHIUM NIPPONENSE

应用石蜡切片和扫描电镜技术对日本沼虾消化道进行了研究。结果表明，食道壁向腔内形成四个纵突，食道上皮由单层柱状细胞构成，上皮下的结缔组织中具有放射肌和皮肤腺，环肌层近于连续。食道和胃连结处的管腔背方具食道瓣，胃内具胃磨、滤器和滤沟等结构，胃的组织学结构中除无皮肤腺分布外与食道相似。中肠较长，约占整个消化道的７１７％，具一对中肠前盲囊。中肠上皮细胞大致有两种类型，基膜着色深，环肌层连续，纵肌成束分散排列。后肠为一短管，管腔呈迷路状，其中部为一球形膨大的直肠。后肠的组织学结构与前肠相似。

The structure of the digestive tract of freshwater shrimp, Macrobrachium nipponense ,was studied with light and scanning electron microscopy.The oesophageal wall formed inward four folds and its epithelium was composed of a layer of columnar cells.Below the epithelium the connective tissue was packed discretely with bundles of radiating muscle and tegumental glands.The oesophagus was enclosed by a layer of circular muscle,beneath which lied discrete bundles of longitudinal muscle.Between the oesophagus and the stomach,an oesophageal valve lied on the dorsal wall of the canal.There were gastric mill,filter and filter groove in the stomach.Histologically the stomach was similar to the oesophagus except the absence of tegumental gland.The mid gut was about 71 1% of the total length of the digestive tract and had a couple of anterior mid gut caeca.The epithelium of the mid gut was generally composed of two kinds of cells.The basement membrane was stained darkly.The circular muscle formed a layer,and the longitudinal muscle was arranged in discrete bundles.The hind gut was a short tube,and a rectum lied in its middle part.Histologically all the parts of the hind gut were similar except more tegumental glands in the connective tissue of the rectum.