206 Colchicine 



In Chapter 16, a technique of inducing polyploidy in vertebrates 

 will be discussed. This involves using sperm treated with colchicine. 

 It should be mentioned here that the alkaloid has not been reported 

 to affect adult spermatozoa. i-- 1'' 



8.2: Colchicine-induced Malformations 



The artificial production of embryonic monstrosities has received 

 a great impetus from the work of Ancel and Lallemand.^' -• -^ This 

 was initiated around 1937, and, together with the use of other chemi- 

 cals, has opened a new field in developmental research. A detailed 

 survey of this is to be found in Ancel's recent book. La Chimiotera- 

 togenese.^ 



Through a small opening in a chick's egg, a minute quantity of 

 a solution of colchicine in saline is introduced. The embryo is ob- 

 served, to make sure that no abnormalities exist at the start of the 

 experiment. The opening is closed and the egg hatched in an incu- 

 bator. 



One of the most striking results was the production of a malforma- 

 tion which had been described in calves by Gurtl (1832) and called 

 schistosomus reflexus. This is a peculiar type of celosomy, that is, a 

 total hernia of all the abdominal and thoracic viscera, residting from 

 an absence of the anterior body wall. Lesbre, in 1927, used the term 

 stropliosomy , or body-turned-inside-out, for the rachis and tail are 

 strongly bent backwards, the hind limbs located close to the back of 

 the head (Fig. 8.2) . Such a malformation had never been seen in 

 chicks, and naturally aroused great interest in colchicine. Further 

 testing of more than fifty substances, several of which induced various 

 abnormalities of development, demonstrated that only ricine and 

 abrine could initiate stropliosomy. 



Figure 8.3 shows the difference between the formation of celosomy, 

 which is much more frequent, and stropliosomy; the posterior bend- 

 ing of the caudal part of the spine plays a great part in the second 

 tyj)e of anomaly. The colchicine treatment of the eggs must be done 

 within a quite definite period. The optimal period is after 48 hours 

 of incubation; before this time, or after 68 hours, it is ineffective. 

 Only 5 hours after the introduction of colchicine into the shell, 

 the embryo demonstrates an exaggerated forward flexion of the infra- 

 cardiac region. Many of the embryos die at this moment. Some also 

 display a dorsal flexion of the caudal extremity of the rachis; these 

 are the ones which will eventually become strophosomic. This mal- 

 formation does not distmb the formation of the embryonic organs, 

 and the chicks are capable of living nearly until hatching, the longest 

 observed duration being 19 days. A similar condition had been 



