Influence of fasting and stimulation on the rat gastric endocrine cells. Histochemical and ultrastructural study

The ultrastructure and certain cytochemical parameters of endocrine cells of the rat gastric mucosa during 168 h of fasting were investigated. To some of the fasting animals peroral food or alcohol was administered before decapitation. The EC (enterochromaffin cells) the ECL (enterochromaffin-like cells), D1 cells, AL (A-like cells) and G cells were identified by means of electron microscopy. Only the EC, ECL, and G cells could be identified by means of light microscopy by an adequate histochemical technique. The ultrastructural picture of the ECL and of the EC cells did not change markedly during the fasting. In the D1 cells there occurred an agglomeration of secretory granules. Some of them disintegrated and disappeared. In the AL cells an agglomeration of granules during the fasting was also observed. Granules engulfed in lysosomes were often found. The participation of lysosomes in the degradation of granules during the fasting was more marked in the AL cells than in the G cells. The participation of lysosomes was questionable in the EC and D1 cells, and in the ECL cells no lysosomes were observed. In contradistinction to the G cells of the non-fasting animals, where more than one half of the gastrin granules were "empty", the G cells during the fasting were filled with agglomerated dense granules and contained lysosomes with fragments of engulfed secretory granules. Following the administration of food (Larsen's diet) 3 h before sacrificing the dissolution of the content of granules with well preserved membranes was observed (emiocytosis did not take place). The administration of food did not lead to changes in the ultrastructural appearance of the EC cells. The peroral administration of alcohol did not lead to any changes in the ultrastructural appearance of the AL and G cells.