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CELL DEATH AND CELL RENEWAL (A)
epithelial cells Cell
shedding 19 Goblet Enterocell endocrine
cells Stem cell (B) Surface epithelium Stem cell Crypt FIGURE 17.19 Renewal of the intestinal epithelium (A) Colon
epithelial cells are renewed by division of stem cells located at the bottom of the intestinal crypt. The stem cell gives rise to a population of
transit-amplifying cells, which occupy about two-thirds of the crypt and
undergo three to four divisions before differentiating into the three cell
types of the surface epithelium (absorptive epithelial cells, goblet cells,
and enteroendocrine cells). The surface epithelial cells continually undergo
apoptosis and are shed into the intestinal lumen. (B) Micrograph of a
colon crypt a...
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