Developmental Changes Of Ghrelin-immunopositive Cells In The Gastrointestinal Tract And Morphological Structure Of Small Intestine In Jining Gray Goat

In the present study, the developmental changes of intestinal mucosal structure ghrelin-immunopositive (ghrelin-ip) cells in the gastrointestinal tract in Jining Gray Goats were investigated. Using the method of histology and immunohistochemistry, morphological structureof small intestinal and ghrelin-ip cells in the gastrointestinal tract of Jining Gray Goat at theages of day0,30,60,90,120,150and180.It will be helpful to understand or hypothesize regarding the physiological role and action mechanism of ghrelin. The results were demonstratedas follows：1. The villi length of each segment of the small intestinal increased gradually from0to30d but shortened from30to60d. After60d, the length of duodenum villi shortened with age and reached a minimum in120days, bur slightly increased at aged150and180d. In the jejunum, the length of villi shortened gradually with age extending from60to180d. The length of ileum villi reached the lowest point at120d and there was no significant difference from90to180d.The depth of crypt of each segment of the small intestinal increased remarka-bly from0to30d ang followed by a downward trend with age. The crypt depth of duodenum,jejunum and ileum reached the lowest at150,180and180d.The V／C value of each segment of the small intestinal fell promptly from the largest at0d to60or90d and slightly increased from then on. There was a steady thickening in muscular layer over the whole experimental period.2. Ghrelin-ip cells which can be classified into open-and closed-type cells were found tobe localized in the mucosa epithelium, glands and lamina propria of abomasums, duodenum, jejunum, ileum, cecum and colon, but not in rumen, reticulum, omasum and rectum. Thegreatest number of ghrelin-ip cells was found in the abomasums and the ghrelin-ip cell density gradually decreased from the abomasums to the colon. The percentage of closed-type cellsto all immunopositive cells also decreased from the abomasums to the colon. With the goatgrowth, the densities of ghrelin-ip cells in the abomasums and jejunum increased from aged0to120d, but slightly decreased at aged150and180d.There was also a steady increase in the number of ghrelin-ip cells from postnatal day0to day90in duodenum, which reached a plateau and remained steady。Very few ghrelin-ip cells were found in the ileum, cecum and colon and the densities of which increased with the age growth. As the results are shown above,the intestinal mucosal structure underwent a series of remarkable changes, especially from30to90d，to perform its digestive and absorptive as well as endocrine．The changes of ghrelin-immunopositive cells in the gastrointestinal tract of growing goats suggest that ghrelin may be involved in gastrointestinal tract development.