File:Epidermis-stem cell models.jpg

Epidermis Stem Cell Models

Models for the generation of a single innermost (basal) layer of cells with proliferative potential and multiple layers of suprabasal cells. Self-renewing stem cells (SCs) exist in the basal layer of the epidermis. Symmetrical divisions produce two stem cells, a process which can serve to replenish vacancies in the basal layer.

• Three-step model - a transit-amplifying (TA) intermediate arises, which has been postulated to divide four to five times before delaminating (straight arrows) and entering into a terminal differentiation program.
• Two-step model - a stem cell divides asymmetrically to preferentially partition proliferation-associated factors into the stem cell daughter while providing differentiation-inducing components to the other daughter, which is fated to become a spinous cell (SP).

• Depending on the orientation of the spindle, the divisions could either result in detachment of the SP daughter from the basement membrane or, if lateral, would then necessitate subsequent delamination of the committed SP daughter.
• The spinous cells enter a program of terminal differentiation as they move outward and are eventually sloughed from the skin surface.
• Differentiating cells are continually replaced by a flux of inner cells committing to terminally differentiate and moving outward.

Related Image: epidermis image without layer molecular information | epidermis image with layer molecular information

Original file name: Figure 2. http://jcb.rupress.org/content/180/2/273/F2.expansion.html (resized) Above text modified from original figure legend.

Reference

<pubmed>18209104</pubmed>JCB

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