Experimental Growth in Animals 219 



work with colchicine. Others will be found in this chapter. Here, 

 as in other fields of colchicine work, problems must not be over- 

 simplified, and here especially, the greatest care should be taken in 

 all quantitative estimations. It is striking that it is when colchicine 

 is considered as a tool that the need for fundamental knowledge is 

 the most apparent. 



9.3: Cellular Multiplication in Normal Growth 



Gro^\•th patterns in the organs of adult animals can be revealed 

 far better after colchicine than with ordinary tissue sections. The 

 alkaloid may do more than simply locate the germinative zones of 

 organs; inider strict experimental conditions, it may solve some 

 quantitative problems of growth. Another method, which has brought 

 excellent results, is to study the growth of explanted tissues. This 

 has been done bv the ordinary methods of tissue culture,-^- ^-' ®* or 



TABLE 9.1 



Mitotic Activity in the Seminal Vesicles of Cas- 



tr.JlTed 80-dav-old Rats Treated With 0.3 mg. of 



Testosterone Propionate 



(Abridged from Burkhart^') 



by a modified technique in which cellular multiplication was ob- 

 served only for a fe\\' hours after explantation.^s, 24-27 Some of the 

 results demonstrating how useful colchicine may be as a tool in such 

 work will be summari/ed here. 



9-3-1 : Studies in vivo. Some of the early work in this field was 

 done on the ovary. Colchicine, l)y increasing from 11 to ,H5 times 

 the number of mitoses that could be observed in the germinal epi- 

 thelium of the ovary of mice, demonstrated that this Avas a region of 

 active growth.^- ■^'*' ^^' ^" Similar facts were observed in guinea pigs. 

 76, 77 Yhe relation between the mitotic activity in the ovarian follicles 



