BONE RESORPTION IN TISSUE CULTURE 625 



MEDIA COMPOSITION FROM RESORBING AND CONTROL CALVARIA 



8 10 12 14 



TIME- DAYS 



Fig. 28A. Comparison of media of parathyroid extract (0.5 u/ml) resorbing 

 cultures versus those of control, relatively nonresorbing cultures with respect to 

 calcium, phosphorus, citrate, glucose, and lactate over a 2-week culture period. 

 Note that the calcium and citrate levels of the PTE resorbing cultures (solid 

 circles) are consistently elevated above the controls (open circles), and that 

 the lactate levels of the controls are higher than those of the parathyroid ex- 

 tract-treated cultures after 6 days. (Data reproduced from Mecca et at., 1963.) 



tivity occurred in the media collected on the 4th day, which cor- 

 responds to the period of most rapid resorption morphologically. 

 Fractionation of whole media without prior hydrolysis showed that 

 the labeled hydroxyproline was not in a large peptide or protein 



