Study on the Digestive Tube During the Embryonic Stage of Gushi Chicken

Gushi chicken is a very famous local variety chicken in China. It shows various qualities such as unique habius, rough-resistant feeding, delicate flesh and so on. In this study we use histology, immunohistochemistry and Molecular biology technologies to research the alimentary tract of Gushi chicken embryo during the development period. For clarification the histological feature of digestive tract systematically. And provide a theoretical basis for further research of digestion physiological.Histological results show that: The endodermal layer begins to invaginate at anterior and caudal of the embryo forming two open ended tubes: the anterior intestinal portal and the caudal intestinal portal.The formation of digest tube is starting. The gut tubes grow and extend from both the cranial and caudal embryonic ends until they meet and fuse at the yolk stalk.after five days’incubation. All segments of the digestive tract showed the same histologic structure during fourth to 6days of incubation. During this period, digestive tract can be divided into esophagus, stomach, preumbilical intestine and postumbilical gut. The lateral of digestive tube surrounded with thick and undifferentiated mesenchyme which derived from splanchnic mesoderm, inside cling the lumina is epithelial lining. in the end of 5 days incubation. Some mesenchyme cells of the preumbilical intestine became circling orientated, called smooth muscle precursor cells which show oblong nucleus. Cecum begins to form after five days’incubation. at 6days of the incubation, digestive tube already can be divided into esophagus, glandular stomach, muscular stomach, duodenum, jejunum, ileum, cecum, rectum. During 7 to 8 days of the incubation, almost all mesenchyme cells has been specific differentiated, appeared portrait differentiated smooth muscle.Abundant and cumulate epithelium mucosae cells. Lamina propria and muscularis mucosae have not yet invaginate in the epithelial lining which forms the fold or villus. Tunica adventitia contains many blood vessels. next I will describe the key features of alimentary tract anterior-posterior.during 13 to 14 days of incubation, apparente esophageal glands start to form in the lamina propria of esophagus which near the stratified epithelium, the nucleus of epithelial lining are round. At the 16days incubation, stratified squamous epithelium can be seen, which contain thin and flat nucleus. afterward esophageal gland increase gradually, the esophagus of newborn chick shows thick stratified squamous epithelium and abundant esophageal glands. We can divide the stomach into glandular stomach and muscular stomach at 6day incubation,glandular stomach have formed big glands. prior to the 6 day incubation time point the morphology of the two stomachs seems very similar, composed of a simple epithelial lining and surrounding undifferentiated mesenchymal cells. Whereafter, glandular stomach glands increase gradually. Until the hatching day the glandular stomach wall displays apparente reticulation, because of the devd glands. Muscular layer of muscular stomach become devd gradually. at 13day incubation. We can see sheeted and bobbed smooth muscle which surrounded with connective tissue, epithelial lining of muscular stomach start to invagination at 13day incubation. Muscular stomach glands can be seen clearly at 16day incubation. small intestine and large inmtestine have similar histological Structures, the height of villus in small intestine show more notable augmentation than large intestine, from duodenum to rectum, villus become thin and flat gradually. Periodic acid-schiff staining shows that positive cells first appear in cecum at 15day incubation, then they will extend to other part of the digestive tract. They mainly situated in epithelial lining and glandular epithelium. During the whole embryonic period of Chick Embryo. Cells of digestive tract colouring more easy, round cells become thin and flat, prismatical, spindle-shaped and so on, differentiate to distinct cells inhabit in different position of the alimentary tract specifically.Results of immunohistochemisty display that hydroxytamine, gastrin, somatostatin immunization positive cells mainly distribute in mucosa, which show round, ellipse, pear-shaped. Ghrelin distribute in everywhere of circular layer and lamina propria or glandular epithelium of glandular stomach. GABA mainly distribute in the circular muscle fasciculately. Hydroxytamine- immunoreactive cells distribute in the whole digest tract except esophagus and muscular stomach., they appeared for the first time at 13 days of incubation in duodenum and jejunum.at 17 days of incubation reach a staged peak. Except duodenum keeps a continuity increase. The distribution density of duodenum is more dense than other parts of the digestive tube. Gastrin immunization positive cells are only distribute in duodenum, jejunum and ileum, and the distribution density of duodenum is more dense than jejunum and ileum. Somatostatin immunization positive cells did not appear in esophagus, muscular stomach and cecum they appeared for the first time at 12 days of incubation in glandular stomach,duodenum at 15 days of incubation.And few at 19 days of incubation in rectum. Ghrelin are widely distribute in almost all endoderm tissues at 4 days of incubation. up to the end of incubation .they become specific distribute in some differential position.they mainly distribute in lamina propria and circular layer. masccline area in esophagus, glandular stomach, rectum is bigger than other parts. GABA first appeared bunchy in myenteric plexus of duodenum at 18 days of incubation.Semiquantitative-PCR show us that ghrelin mRNA mainly Express in glandular stomach、 duodenum and rectum.it first has a a small quantity expression in 4 days’whole embryo, and it has a greater expression in glandular stomach than other parts. In the embryonic period, we haven’t detected the expression of growth hormone in digest tract. Therefore the development of alimentary tract in chick embryo thought to be independent of pituitary growth hormone..All results above show that, development of digestive tube during gushi chick embryonic stage share similar characters, but also have unique laws. All of this can help the further research.