胡氏边白蚁消化系统的微细构造

胡氏边白蚁Marginitermes hubbardi(Banks)消化系统可分为前肠、中肠及后肠三大段.前肠包括葡萄状唾腺、口、咽喉、食道、前胃及贲门瓣;从贲门瓣开始到马氏管着生处为止这一段为中肠;后肠则分为葫芦形胃、结肠、直肠和肛门.其消化系统的特点:在前、后肠有几丁内膜、细胞层上还有一层微绒毛;上皮细胞底膜内陷很深,折叠中夹着许多线粒体;中肠围食膜表面有几丁层一直延伸到后肠;后肠前端膨大的葫芦胃中共生了很多种细菌及原生动物,共生的细菌、动物分泌纤维素酶帮助它消化木质纤维.

FINE STRUCTURE OF THE DIGESTIVE SYSTEM OF MARGINITERMES HUBBARDI (BANKS)

The termite Marginitermes hubbardi (Banks) was collected at the countryside of Tucson,USA,and kept in the laboratory.The fine structure of the digestive system was studied with transmission and scanning electron microscopes according the conventional technique of electron microscopy.It was seen that the foregut possessed a thick intima with longitudinal ridges composing spiny scale-like projections.The epithelial cells possess a layer of dense microvilli beneath the intima.The cardiac valves are situated between the foregut and the midgut and composed of twelve projections of three types and organized into four groups The midgut possesses typical columnar epithelial cells with long microvilli pointing to the lumen which are arranged in a hexagonal pattern when viewed above.The peritrophic membrane is thick and possesses electronic dense inner projections.The anterior portion of the hindgut is enlarged to form the paunch which contains a large quantity of microorganisms to digest cellulose in the food.It has a thin wall and the epithelial cells also possess microvilli beneath the intima.The rectum has six rectal pads and the epithelial cells in the section are rich in mitochondria basal plasma membrane infoldings,assuring the function of reabsorption.