Fine Structures Of The Alimentary Canal And The Malpighian Tubules In Deraeantha Ono Pallas (Orthoptera:Bradyporidae)

In this study,using the stereoscopic microscope and light microscopy,scanning electron microscopy and transmission electron microscopy observation,the fine structures of the alimentary canal and the malpighian tubules in Deraeantha ono Pallas(Orthoptera: Bradyporidae)were researched.Besides to deeply discussed the alimentary canal's structure-function suitability.We compared the alimentary canal and the malpighian tubules to other insects' from the aspects of morphology and histology,but also focused on the study of the regional function of the midgut from the cytology.This thesis will provide auxiliary reference for the research of insect taxonomy,and the basic data about physiology for the biological control of pests.The results showed that the digestive tract of adult Deraeantha ono Pallas ca.10 cm,which is composed of the foregut and the hindgut all from the ectoderm by invagination(with mouthparts and anal opening outward),and the midgut from the endoderm.The foregut is consisted of preoral cavity,gula,membranous esophagus,inflated crop and proventriculus.A keratinization hypopharynx,which have different morphologies of sensory hairs and bristle,located in the preoral cavity.The abundant circular muscles and the longitudinal muscles that only distribute at dosral-ventral are arranged on the outermost of the esophagus,also on its' the inner wall of the anterior and posterior segments have teeth.The crop's outer circular muscles are more abundant,and the inner wall divided into two sides,which are symmetric,have 4 groups ridges through abdominal groove(Arg).The tooth in different forms lay on the inner wall of the crop.The Arg's outer is one bunch of longitudinal muscles.6 rows rides distributed in the proventriculus,with the skeletogenesis tooth line on it.The proventriculus ends in the cardiac valve,which controls the food into the midgut but also prevents the food from the midgut into the foregut.The midgut is divided into the dorsal-ventral gastric caeca and tubular ventriculus.Gastric caeca is composed of the sac lay and the internal longitudinal ridges.Histologically,midgut from outside to inside consists of longitudinal muscles,circular muscles,basal lamina and epithelium layer,which is composed of regenerative cells and columnar cells.At the root of the epithelium,regenerative cells form a crypt.The regenerative cells generate nodules out of basal lamina on the internal longitudinal ridges.Infoldings of the basal membranes of the columnar cells account for a greatly labyrinth.Terminal is microvilli,the length of which increased gradually from anterior to posterior until at the end of microvilli became shorter.Columnar cells have secretion: apocrine secretion and holocrine secretion mainly concentrated in caecum and posterior 2/3 of midgut,the merocrine secretion concentrated in the anterior 1/3 of midgut,and after 2/3 in the midgut region distribution of lipid droplets and particles,in the anterior 1/3 of midgut region only being particles.The hindgut is composed of a funnel-shape ileum,a coiled colon and rectum.The anterior portion of the ileum forms the pyloric valve,which is a door that the midgut enters into the hindgut.There are 6 rectal pads on the inner surface of the rectum.The epithelial layer is composed of the junctional cells and the principal cells.There are teeth on the inner wall of the hidgut except for the surface of the rectal pad,but the tooth shape is similar.Malpighian tube is divided into urinary bladder and free malpighian tubules.Free malpighian tubes' ends gathered at the junction of the foregut and midgut caecum and rectum.The conclusion show that the crop and proventriculus foregut surface morphology can be used as the basis for classification of Orthoptera,and hindgut morphological features have little significance on the classification;The gastric caeca is mainly site of secretion enzymes,which is used for the digestion and absorption of food in the midgut.Malpighian tube may develop from the endoderm and is mainly excretory organ in Deraeantha onos Pallas,but also water is transported into the midgut for reabsorption.