Ageing in Inbred Strains of Animals 



121 



One task of experimental gerontology is to analyse more 

 closely the causes of death in these animals. Our attention 

 was first drawn to a form of amyloidosis which was investi- 

 gated by Thung and co-workers (Thung 1955, 1956; Thung 

 and van Rijssel, 1954). 



Generalized infiltration of tissues with an amyloid-like 

 substance is a frequent occurrence in old mice. If localized in 

 the kidneys, this condition may lead to fatal renal disease, as 



Table I 



Causes of Death in Virgin Females of Different Inbred Strains of 

 Mice and their Hybrids 



has first been described by Dunn (1944). This senile amyloido- 

 sis is dependent upon dietary and genetical factors, which 

 have been analysed by Heston and co-workers (Heston and 

 Deringer, 1948; Heston, Larsen and Deringer, 1945). The 

 genetical aspects may be illustrated as follows: 



The DBA f strain has a high incidence of amyloid in the 

 adrenals and in the ovaries (about 90 per cent in mice over the 

 age of 18 months), while the kidneys are usually only slightly 

 affected or not at all. 



The O 20 strain is practically free of this amyloid degenera- 

 tion. In the adrenals it was seldom seen, while the kidney only 



