784 



Colchicine 



per cent of all the nucleated cells of the marrow were arrested at 

 metaphase."" That this actually decreases the output of young red 

 blood cells was made clear by reticulocyte counts in the blood of 

 rabbits. Normal animals and rabbits with phenylhydrazine-induced 

 hemolytic anemia were utilized (Fig. 7.4 and 7.5) . A sharp but 

 transient iall in the percentage of reticulocytes is a convincing demon- 

 stration ol the inhibition of blood formation. -- 



35.000 7 



I 



30.000 6 



I 



25.000 5 



20.000 _^ 



15.000 



10.000 



I 



5.000 



2.500 



colchicine i 

 jr. 4- 



,r.b.c. xlO^ 



euk. 

 ^r«tic.%o r.b.c. 



SO 

 45 

 40 

 35 



30 



25 



20 



15 



10 



5 



1 



1 



•,\ 



-•— s 





^ I 

 I I 

 I I 





_ 



1 



9 DAYS 10 



F!g. 7.4 — Blood changes in the adult rabbit. Colchicine-leukocytosis and sharp fall of 

 the numbers of reticulocytes (immature red-blood cells). The importance of the mitotic 

 disturbances of the erythroblasts is evidenced by the slow return of the reticulocyte 

 number to normal, and by a slight anemia. (Unpublished, after P. Dustin"^) 



On the other hand, Dixon and Maiden-' disco\ered that in rabbits 

 and dogs an injection of colchicine was followed by a considerable in- 

 crease in the number of circulating white blood cells (Figs. 7.6 and 

 7.7) . These authors, while reporting this curious effect, mentioned 

 that 12 hours after the injection, tlie bone marrow of rabbits apjK-ars 

 empty of most of its nucleated cells. Fhis is in agreement with 

 observations of bone-marrow aplasia, sometimes fatal, which have 

 since been recorded in the medical literature (cf. Chapter 10) . 



The British authors-^ expressed their conclusions in a rather mis- 

 leading way, to cjuote: "evidence is conclusive that colchicine is a pow- 

 erfid stimulant to the bone-marrow, since it tmns out into the circu- 

 lation all the elements including the erythroblasts, and leaves the 



