Brunner's glands of the echidna.

Abstract

AbstractBrunner's glands of the echidna form a thick, interwoven collar confined to the submucosa of the most distal portion of the stomach. The glandular mass ends immediately proximal to the pyloroduodenal junction and empties onto a surface lined by stratified squamous epithelium. Histochemical studies indicate that the secretion elaborated by the glands is an acid mucopolysaccharide.Secretory tubules in the glands consist of large, pyramidal‐shaped cells resting on a delicate basal lamina. They contain large, pale or granular secretory droplets which are membrane bounded and are found in close association with extensive Golgi complexes and also at the apex of the cells. Secretary granules, occasionally fused into irregularly‐shaped complexes in the apical region, appear to rupture the cell membrane and discharge their contents into the adjacent lumen. Small, dense granules are also present but less abundant. The granular endoplasmic reticulum is confined mainly to the perinuclear region and comprises dilated cisternae containing amorphous material. Several small vesicles apparently formed from smooth membrane areas of the ergastoplasm are seen adjacent to the Golgi networks.The epithelium lining the duct is devoid of large secretory granules and contains relatively few organelles.