616 



p. GOLDHABER 



Fig. 15. Six-day control calvaiium (roller tube at 20 per cent Oo). Note re- 

 sorption (R) in median suture area. (X 14.) 



Fig. 16. Six-day culture containing approximately 5 X 10 '^•'' m 2,4-dinitro- 

 phenol (roller tube at 20 per cent Oo). Note inhibition of resorption, although 

 outgrowth is healthy. ( X 14.) 



Fig. 17. Histological section through control calvarium maintained in cul- 

 ture for 2 weeks. Note thick layer of new osteoid (O) on surface of darker, 

 original bone (OB). ( X 325. ) 



Fig. 18. Histological section through 2-week culture exposed continuously 

 to 5 X 10~^ M 2,4-dinitrophenol. Note patch of defective osteoid (O) on 

 surface of original bone (OB) . ( X 325.) 



tion (Figs. 19 and 20). Again, under these conditions, bone forma- 

 tion was not completely inhibited (Figs. 21 and 22), suggesting 

 that bone formation and resorption are independent processes hav- 

 ing diflFerent metabolic pathways. The above findings support the 

 concept that the Krebs cycle is intimately involved in the process 

 of bone resorption. Along these lines, previous concomitant chemical 

 analyses of the supernatant fluid of resorbing bone cultures have 

 revealed a cumulative increase in citric acid over a 10-day culture 



