An Electron Microscopic Study of the Intestinal Villus: II. The Pathway of Fat Absorption

摘要: The intestinal pathway for absorbed fat was traced in thin sections of villi from rats fed corn oil by stomach tube after a fast 24 to 40 hours. For electron microscopy the tissues were fixed chilled buffered osmium tetroxide and embedded methacrylate. light microscopy, other specimens same animals formal-calcium, mordanted K2Cr2O7, gelatin. Frozen stained with Sudan black B or IV. About 20 minutes feeding, small droplets (65 mµ maximal diameter) appear striated border between microvilli. At time particles are seen within pinocytotic vesicles immediately subjacent terminal web. In later generally larger (50 240 mµ) lie deeper apical cytoplasm. All intracellular loosely enveloped membrane, outer surface which is sometimes studded fine particulate component This envelope, apparently derived cell pinocytosis, has at this stage evidently become part endoplasmic reticulum. Just above nucleus numerous clustered dilated cisternae Golgi complex. As absorption progresses intercellular spaces epithelium, interstitial connective tissue lamina propria, lumen lacteals. these extracellular devoid membranous envelope. picture as reconstructed studies involves stream filtering through border, entering epithelial pinocytosis bases intermicrovillous spaces, coursing reticulum be discharged sides into spaces. From move propria thence lymph. If considered continuous phase, then entire may regarded extracellular. However, it impossible evaluate microscopic evidence thus far available quantitative importance mechanism described.