Spontaneous Bone Tumours of Mice

Abstract

This is an account of the origin and establishment of an inbred strain of mice with a high incidence of spontaneous bone tumours. A description of the Simpson Strain maintained in this laboratory since 1929 has been published elsewhere (Pybus and Miller, 1934) in connection with spontaneous mammary carcinoma, the incidence of which is very high. It was known (Marsh, 1929) that, in addition to mammary, liver and lung tumours, occasional sarcomata occurred in the strain, but it was not until 1933, by which time 3 bone tumours and 2 spindle-cell subcutaneous sarcomata had appeared among the descendants of our original pair of mice, that the possibility of establishing an inbred sarcoma strain presented itself. Origin of Sarcoma Strain By 1933 two branches of our Simpson Strain were in existence: one (“Right Ear Punch”) consisting of the inbred progeny of the first litter of the original pair; the other (“Left Ear Punch”) descended from a litter obtained by mating an F1 male with his mother. Of the first 5 sarcomata, 4 were in the L. E. P. Strain, 2 in F3 and 2 in F4. The offspring (or, in one case, litter mates) of these mice were segregated and bred from. Strain A: With the intention of procuring a high incidence as quickly as possible, the F4 sarcoma female, 711, was mated with the son of an F2 sarcoma female, and the 2 daughters of this pairing (mice 1165 and 1166) were mated in turn with 2 sons of an F4 sarcoma male (from an outcross of this male to a R. E. P. female), while mouse 1166 was mated, also, with her own father. The progeny of the 4 pairings were inbred brother to sister for 2 generations, and one pair in the third generation (Fig. 1). Owing to the intentional concentration of the sarcoma character, Strain A seemed to be most promising, but sarcomata were infrequent and late in appearing, and, as better results were obtained in Strain B, breeding was discontinued.