CHAPTER 2 



Nucleus and Chromosoines 



2.1: Original Concepts 



A basic and far-reaching discovery in biology emerged from the 

 activities--'- •^'^ of the Laboratories of Pathological Anatomy, Faculty 

 of Medicine. University of Brussels, under the direction of Professor 

 Albert-Pierre Dustin: Colchicine induced metaphasic arrest 

 (stathmokinesis) . Nuclear mitoses were studied experimentally at 

 Brussels for more than a decade, 1924-1934. chemicals being applied 

 by several methods. After colchicine was suggested, '^^ evaluation of 

 its mitotic activity came quickly, and showed that a powerful agent 

 had been discovered. ComjKuative tests for mitotic poisons proved 

 that colchicine was one thousand times more potent than sodium 

 cacodylate, which they had studied previously. •'^'^ Pure substance, in 

 minute quantity, caused metaphasic stages to accumulate in a treated 

 tissue far beyond the percentages found in untreated sarcomas. These 

 original tests with colchicine, coujiled with previous experience 

 with other mitotic poisons, helped to frame the idea of. metaphasic 

 arrest by colchicine.--' 



7he original slides preserving the tissues treated wiih colchicine 

 were re-examined by the authors when they worked together in 

 1949.-'''^ From these impressive sections, new photomicrograj)hs were 

 made for this book (animal cells, cf. Chapter 10, Fig. 10.1; plant 

 tissues. Fig. 2.1C'). Ihe total effectiveness displayed by the drug act- 

 ing upon mitosis is re-emphasized by these pictures. Microscopic in- 

 spection reveals an luiusual sight. Similar impressions of this totally 

 different mitotic picture had been formed earlier when the senior 

 author, -^^ in 19.S7, saw animal cells treated with colchicine and placed 

 beneath the microscope (cf. Chaj)ter 1) . The jjower to sto)) mitosis 

 in metaphase was clear to us, and this property has been confirmed by 

 many experimenters. •^•'' Everyone agrees that the reaction upon nuclear 

 mitosis is specific, selective, and total, inider prescribed conditions. ^•'- ^^ 



A large bibliography^-^ has accumulated since 1934, but one of the 

 original conclusions, metaphasic arrest, conceived by Professor A. P. 



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