Abstract
Six populations of bone cells (populations 1-6) were obtained by sequential digestion of mouse calvaria with collagenase and trypsin. After release from the tissue, each cell population was cultured for seven days. Parathormone, but not calcitonin, elicited an increase in intracellular cyclic AMP in the cells of populations 4, 5, and 6. In contrast, both hormones elicited increases in cyclic AMP in populations 2 and 3 but had no effect on population 1. When the cells of population 2 were exposed to a Falcontissue culture polystyrene surface for periods of time up to 5 min, many cells adhered. The nonadhering cell population contained a lesser proportion of cells responsive to calcitonin, whereas the adhering population contained a greater proportion responsive to this hormone. Conversely, when the cells of population 2 were exposed to an acid-treated nylon surface, the nonadhering cells contained a larger proportion of those responsive to calcitonin and a smaller proportion responsive to parathormone. When those cells that were enriched for calcitonin responsiveness were examined, we found an increased proportion that exhibited an asymmetric bipolar morphology. These differed from large amorphous, often binucleate, cells which predominated in those populations that responded exclusively to parathormone. These results establish that bone contains at least two types of target cells--one that responds to parathormone but not calcitonin, the other that responds predominantly to calcitonin.