[Ultrastructural and cytochemical study of the endocrine serotonin secreting cells of the fetal and adult rabbit intestinal mucosa].

Endocrine cells of intestinal mucosa have been studied in rabbit fetuses and adults. The problem of an ultrastructural identification of "preargentaffin" serotonin cells has been elucidated comparing cytochemical and ultrastructural datas. Since all cells exhibiting a yellow formaldehyde-induced fluorescence reacted with Sevier-Munger method and since all impregnated cells were fluorescent it has been concluded that impregnated cells at the electron microscope level are serotonin cells; these cells had generally small and round granules. Another cell type with small round granules showing deposition of silver grains on the outer rim has been identified as granular S cells.