Immunocytochemical and electronmicroscopical data on the differentiation of somatostatin-containing endocrine cells in human large intestine.

The distribution and ultrastructure of the somatostatin-containing endocrine cells in the distal large intestine of fetuses, children and adults was investigated by silver impregnation, immunocytochemical and electron-microscopical techniques. Somatostatin-containing endocrine cells in 10-14-week-old fetuses were found to differentiate very intensively. In 19-25-week-old fetuses the frequency of occurrence began to decrease and this tendency was preserved during the subsequent stages of ontogenesis. Conversely, the frequency of occurrence of argyrophil endocrine cells increased. The change in the mean diameters of the secretory granules was also studied.