Goblet and secretory cells. Coloured transmission electron micrograph (TEM) of a section through a goblet cell (red & dark brown) and secretory cells of the duodenum, part of the small intestine. The goblet cell secretes mucus which neutralises stomach acid. The mucigen granules (circular objects, at upper centre) combine with water to form the mucus. On either side of the goblet cell are the secretory cells whose secretions help in the digestive process. The microvilli (blue hair- like structures, upper frame) serve to increase the secretory capacity of the secretory cells by increasing their surface area. Magnification unknown.