Mechanisms of bone resorption in calcium-deficient rats.

A study of surface remodeling activity and osteocyte lacunar area was made in young and adult rats maintained on a low-calcium diet, to explore cellular mechanisms of bone resorption. The diet produced active remodeling of the endosteal part of the femoral cortex, with a decrease in the amount of bone present. Surface resorption, with numerous osteoclasts, was evident, but there was no evidence of osteocytic osteolysis in bone which, by tetracycline labeling, could be identified as existing at the commencement of the experimental period. Osteocyte lacunae in bone formed during the period of calcium deprivation were somewhat larger than lacunae in control animals, apparently because of interference with the formation or maturation of the perilacunar tissue.