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Multiple osteoblasts recorded. In the TEM image , the osteoid synthesized by the osteoblasts is clearly visible as a light-colored zone (black borderline) with two embedded osteocytes, which is sharply delineated towards the mineralized bone matrix.

Osteoblasts ( singular osteoblast ) are cells that are responsible for the formation of bone tissue during bone remodeling . They develop from undifferentiated mesenchymal cells , embryonic connective tissue cells. They form the basis of the bone substance, the bone matrix (osteoid), by mainly excreting type 1 collagen and calcium phosphate in the form of hydroxyapatite into the interstitial space. Osteoblasts have long cell extensions with which they remain in contact with the non-mineralized tissue or via gap junctions with neighboring osteoblasts. In the process of bone formation, osteoblasts change into a scaffold made up of osteocytes that are no longer able to divide and slowly mineralize and fill with calcium .

The opponents of the osteoblasts are the osteoclasts . Osteoblasts regulate the function of osteoclasts directly through the secretion of signaling substances: on the one hand through the activating RANK ligand (RANKL), on the other hand through the inhibiting osteoprotegerin (OPG), which neutralizes RANKL.

Degenerate osteoblasts can cause osteoblastomas , a type of bone tumor.

Individual evidence

  1. Thomas Heinzeller, Carl M. Büsing: Histology, Histopathology and Cytology for an introduction . Georg Thieme, Stuttgart 2001, ISBN 978-3-13-126831-0 , p. 83.