232 Colchicine 



epidermis of the ear considerably more during estrus than during 

 diestrus. The mitoses were counted hour by hour by cHpping small 

 Iragments of the ear. This difference can be explained by a shorten- 

 ing of the time taken for one division, from about 2 hours in diestrus 

 to 34 hour in estrus. This significant result is not discussed; other 

 possible hypotheses are, for instance, synergic action of colchicine 

 and hormone, or changes in the duration of interphase. The alkaloid 

 is simply considered to stop metaphases.-- -"'• "- 



Androgenic hormones, also, stinudatc mitotic growth, and the 

 use of colchicine was advocated in 1937 for the study of the changes 

 in the seminal vesicles'*'*' *'•''• ^- (Fig. 9.7) . The accumulation of arrested 

 mitoses in the prostate or seminal vesicles of castrated mice or rats 

 has been projjosed as a test for androgens.'''' In mice, colchicine 

 helped to jjrove that the prostate is a more sensitive reactor than 

 the seminal vesicles to testosterone.^^ Data about the "explosive" 

 aspect of mitotic stimulation when studied with colchicine in these 

 tissues has been discussed already and presented in Table 9.1. 



The quantitative aspects of the seminal vesicle reaction to various 

 androgens and related hormones have been carefully investigated.^*^' *^ 

 Figure 9.8 demonstrates how the increased number of mitoses heljjs 

 to establish the linear relations between the doses of androgen in- 

 jected and the intensity of the reaction. With other hormones, such 

 as progesterone and estrogens, though the mitotic index may increase, 

 no such relation is foiuuH" (Fig. 9.9) . 



Colchicine also brought further evidence that in the female 

 guinea pig, the epoophoron reacted to colchicine like the male epi- 

 didymis, of which it is the anatomical homolog.*^ 



g.^-^: Mitotic sti/nuldllon o^ endocrine glands. Though pituitary 

 hormones play a great jxirt in mitotic stimulation in various organs, 

 the cells of the pituitary may also undergo mitosis under the in- 

 fluence of hormonal stimuli. '^^ ■^''' "^ Colchicine helped to demonstrate 

 that in virgin female rats, ovariectomy did not promote pituitary 

 mitoses. ^'-^ On the contrary, injections of estrogens, natural or syn- 

 thetic, enlarge the pituitary as a consequence of mitotic growth made 

 evident with colchicine.''"* It has, however, been shown that castration 

 could influence the numbers of c-mitoses of the basophil cells of the 

 anterior lobe of the i)ituitary.'^i There are no data about the posterior 

 lobe of the organ, which may be an interesting object for future col- 

 chicine work. 



Several papers deal with mitotic stimulation in the cortical region 

 of the adrenals.'-*-' ^'^^ «''' ^••'' *' In inmiature female rats, colchicine re- 

 veals a stimulation which reaches its maximum 96 hours after an 

 injection of testosterone. At the same time, however, mitotic activity 

 is increased in thyroid, parathyroid, and ovary. This may be evi- 



