Figure 1621

Diagrams of an enterocyte in different phases of absorption, a. This cell has a striated border on its apical surface and junctional complexes that seal the lumen of the intestine from the lateral intercellular space. The characteristic complement of organelles is depicted in the diagram, b. This cell shows the distribution of lipid during fat absorption as seen with the TEM. Initially, lipids are seen in association with the microvilli of the striated border. Lipids are internalized and seen in vesicles of the smooth endoplasmic reticulum (sER) in the apical portion of the cell. The membrane-bounded lipid can be traced to the center of the cell, where many of the lipid-containing vesicles fuse. The lipid is then discharged into the intercellular space. The extracellular lipids, recognized as chylomicrons, pass beyond the basal lamina for further transport. (Based on Lentz TL. Cell Fine Structure: An Atlas of Drawings of Whole-Cell Structure. Philadelphia: WB Saunders, 1971.)

terminal web lysosomes microvilli junctional complex terminal web lysosomes microvilli terminal web lysosomes microvilli junctional complex terminal web lysosomes microvilli

chylomicrons
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