The ultrastructure of the gastric glands and its relation to induced secretory activity of cod,Gadus morhua (Day)

Light and electron microscopic studies have been performed on different parts of cod stomach. The studies have been concentrated on the gastric glands of the gastric mucosa. The glands consist of only one cell type. This cell contains an apically located, comprehensive tubular system as well as zymogen granules and therefore probably secretes both acid and zymogen. The high degree of development of certain organelles and their mutual localization shows a structural organization which appears suitable for an effective secretion. What appears to be intermediate organelle forms are common. When acid secretion is increased by continuous intramuscular infusion of histamine or of carbachol the most marked structural changes are increases in the size of the gland lumen and in the cell membrane facing the lumen. Histamine in particular causes the appearance of numerous long and slender cell processes in an enlarged gland lumen. When the acid secretion, increased by histamine, had reached a plateau, metiamide was infused. This histamine H₂-receptor antagonist caused a decrease in acid secretion as well as in the size of the gland cell surface to values characteristic of untreated cod.