Unformatted text preview: stine is lined by a single layer of
epithelial cells that are responsible for the digestion of food and absorption
of nutrients. These intestinal epithelial cells are exposed to an extraordinarily harsh environment and have a lifetime of only a few days before they
die by apoptosis and are shed into the digestive tract. Renewal of the intestinal epithelium is therefore a continual process throughout life. New cells This material cannot be copied, reproduced, manufactured, or disseminated in any
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18 CHAPTER 17 Hematopoietic
stem cell Myeloid Reticulocyte Megakaryocyte Lymphoid Monocyte Erythrocyte
Macrophage Eosinophil Basophil B lymphocyte T lymphocyte Granulocytes FIGURE 17.18 Formation of blood cells All of the different types of blood
cells develop from a hematopoietic stem cell in the bone marrow. The precursors
of differentiated cells undergo several rounds of cell division before they differentiate. are derived from th...
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