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Unformatted text preview: em cells
gland Differentiation Transitamplifying
Epidermal stem cell FIGURE 17.20 Stem cells of the skin The epidermis consists of multiple layers
of epithelial cells. Cells from the surface are continually lost and replaced by epidermal stem cells in the basal layer. The stem cells give rise to transit-amplifying
cells, which undergo several divisions in the basal layer before differentiating and
moving to the surface of the skin. Stem cells of hair follicles reside in a region beneath the sebaceous gland called the bulge, and distinct stem cells of the sebaceous gland reside at its base. which proliferate and differentiate to form the hair shaft. Finally, a distinct
population of stem cells resides at the base of the sebaceous gland. It is
notable that, if the skin is injured, stem cells of the bulge can also give rise
to epidermis and sebaceous glands, demonstrating their activity as multipotent stem cells from which both skin and hair can be derived.
Skeletal muscle provides an example of the role of stem cells in the repair
of damaged tissue, in contrast to the continual cell renewal just d...
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