Alexander Lipschiitz 



303 



pig with small quantities of estrogens and the cervical mucosa had undergone 

 cornification. It follows from our comparative work in rats and guinea pigs 

 that the metaplastic pluristratified epithelium of the endometrium in the 

 guinea pig is unable to undergo keratinization as in the rat. Neither were 

 there (in the guinea pig) the great increase in size and the tumoral transforma- 

 tion of the anterior lobe of the hypophysis which so readily appears in the rat 

 (McEuen, Selye and CoUip;'* Zondek"). The mammary gland, which in the 

 guinea pig greatly increases when treated with estrogens, never became adeno- 

 carcinomatous, while this is characteristic for certain strains of mice. In guinea 



TABLE 1 



Territories 



Endometrium. 



Anterior lobe of the hypophysis 



Visceral and parietal serosa. . . . 

 Mammary gland 



Type of reaction in 



Guinea pigs 



Pluristratified metaplasia 

 without cornification 



Never great increase in size 



Abdominal fibroids 



Rarely adenofibroma; never 

 adenocarcinoma 



Rats 



Pluristratified metaplasia 

 with cornification 



Enormous increase in size, 

 sometimes abnormal and 

 tumoral. 



No abdominal fibroids. 



[Mice: adenocarcinoma] 



pigs we found adenofibroma on two occasions and slight metaplastic changes 

 also in two cases. As to the abdominal serosa, the difference between guinea 

 pigs and rats is very marked. Quantities forty times greater than those which 

 induce fibroids in almost every guinea pig fail to elicit any macroscopically 

 visible reaction in the visceral or parietal serosa of the rat (Lipschiitz, Egana, 

 Szabo and Lecanellier^). 



The above statements give full evidence that homologous territories respond 

 to the tumorigenic stimulus of estrogens in a diff:erent manner according to 

 the species, as is also the case with carcinogenic hydrocarbons. The organism 

 may be considered tentatively as a mosaic of territories each of which obeys 

 its own laws in development of experimental tumors. It is very likely that 

 similar conditions prevail also with respect to spontaneous tumors. According 

 to Loeb'^^ it is probable "that each type of tumor is hereditarily transmitted 

 without regard to other types of tumors." 



IV. Experimental Tumorigensis Elicited by Endogenous Hormones 



It has been shown by our former work (Lipschutz™""') that atypical prolifera- 

 tion of the epithelium of the uterine mucosa may be seen in the guinea pig 

 when protracted follicular phases are produced by experimental inicr\cnti()n 



