RESUMEN
5-HT immunoreactive cells(EC cells)in the gastrointestinal tract were studiedby immunogold silver staining method and PAP method in sixty human fetuses aged8-38 weeks of gestation.The results indicated that the appearance of EC cells wasas early as 8 weeks of gestation in the epithelium of duodenum.After 12 weeks ofgestation,the EC cells can be found in the whole human fetal gut.The number ofEC cells(EC cells with visible nucleus per visual field)at all period of gestationalways decreased in an order from the mucosa of duodenum,jejunum,ileum,ap-pendix,colon and stomach respectivly.EC cells in the mucosa of antrum often po-ssessed long processes contacted with other types of glandular cells.The EC cellswere open typed cells except those in the fundic mucosa.Grouped EC cells can alsobe seen in the mucosa of appendix and the intestinal glands.
RESUMEN
The ultrastructure of EC cells in the goose intestine was studied by means of antibody-colloid gold technique with high specific rabbit anti-5-hydroxytryptamin serum.Electron microscopic observation showed that the EC cells were characterized by markedly pleomorphic secretory granules (round, ovoid, pyramidal, rod-, pear-and kidney-shaped etc.). Most of the secretory granules showed high electron density with heterogeneous internal structure, but many with central cavitation and a few with central dense body and less dense in the periphery. The bounding membrane of secretory granules adhered closely to the cores. In duodenum, the EC cells can be grouped into two populations, one with smaller secretory granules and the other with larger. The EC cells with smaller granules were predominant in duodenum. In caecum, the maximum diameter of the secretory granules of EC cells was larger than that of duodenal EC cells. Many long cytoplasmic processes of EC cells, shaped 'leg-foot' like, were observed in caecum. The processes began at the basal part of EC cells and extended along the basement membrane.