Pathways regulating bone resorption

Published on January 19, 2015   40 min

Other Talks in the Series: Bone in Health and Disease

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Osteoclasts are among the most remarkable cells in the body. In this lecture, in addition to outlining their key regulatory pathways, I want to address some aspects of osteoclast biology that might be less well known, with a special focus on the roles of the fundamental parameters, oxygen tension, and pH.
If you want to see osteoclasts in action, a good place to start is actually to look at erupting teeth in the developing jaw. In this image, you can see adult teeth embedded in the jaw, and milk teeth protruding from the gum above. The developing adult teeth that are embedded in the jawbone have to make their way through the jawbone in order to erupt and serve their function.
This image shows, in higher power, the developing, erupting adult tooth surrounded by the concave bone. Lining the bone, you can see a number of large cells is the osteoclast. And these are in the process of eroding away the bone of the jaw, the alveolar bone, in order to make way for the tooth.
At higher power, we see the row of osteoclasts on the bone's surface. And we see that each osteoclast is embedded in a concavity in the bone. This is the process of bone resorption. In juveniles, such as the specimen we're seeing here, osteoclasts may be quite frequent.
However, in adult bone, osteoclasts occur far less commonly. But, for example, if we look at this section of a human finger bone, there's only a very small area, highlighted here, in which osteoclast activity is evident.