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Dr. Ebraheim’s educational video describing Osteoclasts - bone absorption. The origin of osteoclasts my come from fusion of the macrophages/monocytes. As many as 50 of the cells fuse together to form a giant osteoclast cell. Osteoclast cells absorb bone. The lifespan of osteoclasts is a few days. One osteoclast can create a lot of damage. It will take three months to replace the bone that has been removed within only a few days by the osteoclasts. It may take 100-150 osteoblasts to replace the bone that has been removed by one osteoclast. The osteoclast cell has a lot of mitochondria (it is actually a machine). The osteoclasts is found against the bone surface in a hollow depression called the Howship’s Lacunae (where bone resorption occurs). The Howship’s Lacunae is the site of bone resorption where the ruffled border meets the bone surface. When the osteoclast absorbs the bone, it develops a ruffled border and a sealing zone. Osteoclasts secrete two enzymes: Cathespin K (CTSK) is an enzyme
