122 O. Muhlbock 



exceptionally showed amyloid disease. The O 20 X DBA f 

 hybrids, however, are very frequently affected. Above an age 

 of 20 months various organs are increasingly affected, the 

 incidence in the adrenals and in the kidneys being around 

 90 per cent at 24 months. 



The amyloid degeneration of the mouse kidney may be 

 briefly described as follows: while amyloid may occur in the 

 glomeruli, its most frequent site is the interstitial tissue of the 

 renal papilla. The amyloid deposits here lead to obstruction 

 of the Bellini ducts. Infection may secondarily occur, and the 

 final result is atrophy and degeneration of the renal tubules, 

 often in wedgelike areas. For this process Dunn has proposed 

 the name "papillo-nephritis". This degeneration may be 

 accompanied by cystic dilatation of the tubules and of the 

 Bowman capsules. According to the occurrence and degree of 

 these dilatations, two varieties of the affection are discernible 

 macroscopically : the cystic and the atrophic form. 



The occurrence of these dilatations also depends upon 

 genetical factors. The cystic form of papillo-nephritis is 

 found in C 57 BL mice and is most frequently found in C 57 BL X 

 DBA f hybrids. In O 20 X DBA f hybrids, on the other hand, the 

 atrophic form is usually found. 



These lesions of the kidneys are but one instance of senile 

 changes leading to death. Many others certainly remain to 

 be analysed. In these investigations a comparative analysis 

 of the functions of young and old organs and tissues is 

 necessary. 



Transplantation Experiments 



One of the outstanding advantages of inbred strains is the 

 possibility of transplantation of tissues and organs from one 

 animal to another, either within the inbred strains or from an 

 animal of an inbred strain to one of its F x hybrids. The 

 reverse, i.e. transplantation of organs and tissues from an F x 

 hybrid into one of its parent strains is not possible. 



The use of this transplantation method can be demonstrated 

 with the transplanted ovaries, in which the function of the 



