264 



BIOLOGY OF THE LABORATORY MOUSE 



Hormonal influences. — Although the distribution of lung tumors is not 

 exactly equal between the sexes, the investigations reported by various 

 workers give conflicting results. 



Slye, Holmes and Wells (93) recorded 57.4% of their lung tumors in 

 female mice and 42.6% in males. Lynch, on the other hand, in a large group, 

 obtained among females an incidence of 16% and in males 22%. 



Bittner's figures are again the most extensive available. The incidences 

 in the two sexes and in various generations are shown in Table 12. 



Table 12 

 Lung Tumor Incidence Following Reciprocal Crosses between A and 



Cs7 Black (B) Strains 



The incidence in the two sexes is thus approximately the same, and no 

 evidence of hormonal influence exists. 



Coat color. — Heston's work, referred to above, was planned to detect any 

 signs of linkage between certain of the common genes for coat color and the 

 tendency to form lung tumors if any such relationship existed. The genes 

 involved were the following pairs: 



C = color 

 A = agouti 

 B - black 



No evidence for linkage was found. 



c = albinism 

 a = non-agouti 

 b = brown 



Non-epithelial Tumors 



Under this very broad heading are included a large number of different 

 types of neoplasms. 



In spite of a large amount of pedigree data collected by Slye (86-92) and 

 others, there still is lacking a sulhcient number of animals with any one type 

 of tumor in any one inbred line of mice to give adequate and significant 



