Experimental Growth in Animals 229 



vesicles in the guinea pig. This figure Avas increased to 16.8 by the 

 hormone alone, and to 119 by hormone -j- colchicine.^- A method 

 tor the detection of increased amounts of this hormone in the urine 

 ol patients has been proposed^i (Table 9.6) . A response is positive 

 when more than 4 mitoses per 100 vesicles are detected." Other 

 authors have confirmed these results, but some abnormal resjjonses 

 were attributed to a rhvthmic growth response of the thyroid. "^^ 



The gonadotropic hormones stimulate mitotic growth in many 

 tissues, and this was studied by means of colchicine as early as 1937.^- 

 In the uterine glands of guinea pigs, colchicine made clear the 

 location of the zones of maximal growth. Action of pituitary hor- 

 mones on endocrine glands will be considered later. Results of work 

 on pregnant guinea pigs may be mentioned however, because they 

 bring e\idence of many, often unsuspected stinudations of mitosis 

 by the increased amount of gonadotropic and other steroid sex 

 hormones during pregnancy. -^^ Especially notable is the stimulation 



TABLE 9.6 

 Mitoses in One Microscopic Field in the Thyroid of the Guinea Pig 



(After Bastenie") 



of the paratltNroids, exocrine glands of the pancreas, and kidney 

 tubules — changes which would have been unnoticed -without col- 

 chicine. This important work does not seem to ]ia\e been pursued so 

 far as colchicine is cone erned (Table 9.7) . 



The absence of pul)lications on the adrenocorticotropic hormone 

 (ACTH) and colchicine has already been mentioned.^* It is still 



