The ultrastructure of endocrine cells in the corpus of the stomach of human fetuses.

The ultrastructural development of endocrine cells from the corpus of fetal human stomachs is described. Samples were taken from fetuses ranging in fertilization age from 6-8 to 22 weeks. The identifying features used for the classification of the various types of endocrine cells were their basal locations in the epithelium, the presence and morphology of their characteristic granules and the sizes of the mitochondria. Five types of endocrine cells with specific granules were found:D, EC, ECL, AL and D1. The type and number of endocrine cells increased as development proceeded. The endocrine cells were confined to the epithelium, they did not reach the lumen and they appeared to develop in situ. The D, EC and ECL cells were the most numerous. The fetal endocrine cells resembled morphologically those found in the stomachs of various adult animals. The EC, ECL and D1 cells contained small slender mitochondria with few cristae. Intramitochondrial granules were absent in all the cell types. Agranular electron-lucent cells with small mitochondria were considered to be immature endocine cells. The advanced stage of differentiation observed in these cells suggest that they may be capable of producing and storing biogenic amines and polypeptide hormones. Their possible involvement in the synthesis of serotonin, enteroglucagon and intrinsic factor is discussed.