Stem cells are not just for embryos!  Stem cells are essential in many organs and tissues throughout our adult bodies.  For example, our intestinal tissue constantly replenishes itself in a fascinating assembly line that begins with stem cells.  Today’s image is from a paper that discusses the signaling in an intestinal stem cell. 

Our intestine is lined by sheets of cells that are folded and shaped into finger-like projections called villi (which means “shaggy hair” in Latin).  These villi help increase the surface area in the intestine in order to absorb as many nutrients from our food as possible.  Each villus is a tiny organ of its own, with different cell types and even stem cells.  The crypt base columnar (CBC) stem cells sit at the bottom of the villi and maintain the number of cells in the intestine.  A recent paper identified a role for a common signaling protein, Notch, in CBC stem cell function.  According to VanDussen and colleagues, Notch helps regulate the decision for stem cell self-renewal versus differentiation into specific cell types.  In the images above, intestinal tissue shows a marker for CBC stem cells (green) and for dividing cells (red).  In normal tissue (left), CBC stem cells were found at the base of the crypts.  Some of these CBC cells were also actively dividing (cell with both red and green, arrows).  Notch inhibition (right), however, caused CBC cells to be misshapen and to weak stem cell marker staining.  Notch inhibition also caused a drop in the number of CBC cells that were actively dividing (arrowheads on left), causing a decrease in the total number of CBC stem cells.

For a more scientifically detailed description of this image, check out my post on The Node, the community forum for and by developmental biologists.