Growth and remodeling of bone. An investigation in chicken with special reference to the mechanism of bone resorption.

Bone resorption was studied in chicken by means of histologic and microradiographic examination after intravital injections of three boneseeking fluorochromes. The fluorochromes were injected at intervals from 36 hours to 5 days, and the chicken were killed at 36 hours to 10 days after injection of the third fluorochrome. Signs of osteolysis, such as enlarged osteocyte lacunae surrounded by a metachromatic zone in toluidine blue stained sections, and confluence of osteocyte lacunae in microradiographs, were compared with the fluorochrome labelling pattern. There was no correlation between the histologic findings of osteolysis and the fluorochrome resorption pattern which indicated that existence of so-called bone flow. In the "haversian systems" at midshaft level, the color pattern remained unchanged till resorption took place from the endosteal side. Osteoclasia seemed to be the dominant mode of resorption. The conclusion was drawn that bone flow does not exist in the tibiae of chicken.