A Sex-Difference in the Incidence of Bone Tumours in Mice

Abstract

In a previous account (1) of the development of an inbred strain of mice with a high incidence of spontaneous bone tumours, it was mentioned that sarcomata in general seem to occur more frequently in the females than in the males of the Simpson Strain. Figures were given for sarcomata of all types and in all sites in the entire Simpson stock maintained in this laboratory, including those branches which had been inbred to produce a strain of high sarcoma incidence. Recent observations on the inbred Sarcoma Strain have confirmed the earlier observations as to sex incidence. Originally developed from three females and one male, which had all produced bone tumours, the strain is now in its eighth generation of brother-to-sister inbreeding, a number of separate lines being continued. Only five other instances of double-sarcoma matings have so far occurred within the strain. The tumour arising from bone, of which a very brief description has been given (2), is the preponderant neoplasm in the strain; no other type of sarcoma has yet been found. Up to March 17, 1938, there were 195 deaths among the mice of sarcoma age belonging to F1 and subsequent generations; among these, there were 104 instances of bone tumour, an incidence of 53.3 per cent. Of the total number of animals dying, 97 were females and 98 males. Bone tumours appeared in 75 of the females, an incidence of 77.3 per cent, and in only 29 of the males, or 29.6 per cent.