Fig. 6. Light microscopy and transmission electron microscopy of the duodenal mucosa epithelium of fasting caimans. The enterocytes are narrow, contain no lipid droplets, and are arranged as a pseudostratified epithelium. The brush border is barely visible. The connective tissue cores of the villi are broader and more condensed than in digesting caimans. (A) Low power light micrograph, showing the arrangement of arrangement of the enterocytes as typical pseudostratified epithelium. Note the aggregation of lymphocytes at the base of the middle villus. (B) High power light micrograph of the mucosa epithelium (same magnification as Fig. 5B). (C) Transmission electron micrograph of the mucosa epithelium with enterocytes and one enteroendocrine cell, the lumen of the gut contains an accumulation of cellular debris. (D) Segment of the cell membrane of two adjoining enterocytes showing folds of spare membrane (arrows). (E) Microvilli of an enterocyte exfoliating membrane vesicles from the tip of the microvilli. (F) Bifurcating microvilli. (G) Microvilli of the brush border disintegration, i.e. swollen tips and formation of membrane vesicles. bb, brush border; cd, cellular debris in lumen of gut; eec, enteroendocrine cell; gc, goblet cell; iel, intraepithelial lymphocyte; l, lymphocytes; m, mitochondria; mc, mast cell; mv, microvilli; mvs, membrane vesicles; n, nucleus of enterocytes; smc, smooth muscle cell.