248 



J. A. Fernandez de Valderrama, L. M. Munuera 



2. "Stromba" alone 



No definite changes from the normal were observed. 



3. Cortisone followed by "Stromba" 



5 days after the administration of "Stromba" had begun there were many plump 

 osteocytes, together with evidence of new bone formation in the cortex. There was 

 also new bone formation in the metaphysis, and many new vessels. On the meta- 

 physeal side of the growth cartilage the number and calibre of vessels had returned 

 to normal. The greatly enlarged cartilage cells did not take part in subsequent endo- 

 chondral ossification but the vessels reached to the normal distance from the pro- 

 liferative zone, which had also regained its normal activity. 



Storey (1958) has shown that after cessation of cortisone administration in 

 growing rabbits there is a surge of new bone formation. To establish that the anabolic 

 agent has a direct effect, and that we were not merely observing a "rebound" pheno- 

 menon, cortisone administration in a third group of animals was continued con- 

 currently with the "Stromba" administration. 



4. Cortisone followed by Cortisone plus "Stromba" 



Most of the effects observed were exactly the same as those seen when cortisone 

 administration was discontinued before the anabolic agent was given (5 mg/kg). 



There were plump matrix forming cells. Proper vessel formation was seen and the 

 vessels reached to the normal distance from the proliferative zone (Fig. 2). Normal 



Fig. 4. After 1 week administration of cortisone and cortiM.nc jnj 

 is obvious new bone formation with p.iiti.ilh till 



enchondral ossification was also in progress (Fig. 3). The abnormal cartilage remained 

 unresorbed, and in many areas was covered by a surface layer of bone. In the cortex 

 some of the enlarged osteocyte lacunae filled in again; and resorption cavities became 

 filled with new bone (Fig. 4). 



