Abstract:The expression of ghrelin,KGF,TGF-β2 and TGF-β3 in gastrointestinal tract of Buteo hemilasius was investigated by immunohistochemistry combined with stereological methods,and the expression intensity of these growth factors was analyzed by IPP professional image analysis software. Results showed that ghrelin immunopositive cells mainly distributed in the mucosal layer of all intestine segments:duodenum,jejunum,ileum,caecum and rectum. The ghrelin immunopositive cell density gradually decreased from the duodenum to the caecum,and its distribution density in the rectum was higher than that in the caecum. Gastrointestinal tract showed positive KGF immunoreactivity. KGF immunopositive cells mainly distributed in the epithelial cells of the superficial glands and deep glands of glandular stomach mucosa,as well as mucosa,simple tubular glands of muscular stomach. KGF immunoreactive cells were also found in the blood vessel,lymph and smooth muscle fiber of the intestine lamina propia. TGF-β2 and TGF-β3 immunopositive cells were found in the mucosa,and deep glands of glandular stomach,simple tubular glands of muscular stomach,intestine,and intestinal glands. They mainly distributed in the cytoplasm of the epithelial cells. Analysis of images showed that the KGF displayed a wave-like distribution pattern in the gastrointestinal tract,with the maximal distribution in the jejunum and rectum. The TGF-β2 also displayed a wave-like distribution pattern in the gastrointestinal tract,with the maximal expression in the muscular stomach and jejunum. The expression of TGF-β3 increased from glandular stomach to jejunum,decreased progressively after jejunum,and increased again in caecum. The expression of ghrelin,KGF,TGF-β2 and TGF-β3 may be closely related with the digestive function of gastrointestinal tract. Their coordinated expression may control the growth and development of gastrointestinal tract in birds.