Transplantation behavior and cytogenetic characteristics of a spontaneous reticulum cell sarcoma in the golden hamster

During a period of 2 1/2 years, 33 spontaneous reticulum‐cell sarcomas arose in our colony of golden hamsters. One of the tumors, made transplantable in the solid and the ascitic form, is described with regard to behavior in homologous hosts and to cytogenetic characteristics. During four years of transplantation, the tumor changed its pattern of growth and, after an initial phase of localized growth, displayed a leukemialike mode of spread resulting in the death of the hosts on the 6th or 7th day irrespective of site of transplantation. Animals of the same passage reacted differently to tumor implantation: some hamsters developed large tumors without tumor cell spread, others showed very small tumors with heavy tumor cell dissemination. These different modes of growth are assumed to be dependent on host factors. Chromosome analyses were carried out on tumor cells of different transplantation generations. The chromosomes in cells of the 38th generation did not differ from normal hamster cells, except for a higher variation in the number of chromosomes. Within the next 15 passages the karyotype changed considerably, but from then on remained stable with a stemline of 44 chromosomes and six markers. The late replication pattern of sex chromosomes and of most of the autosomes seems to be the same for both normal hamster cells and tumor cells. The DNA content of the tumor cells was found to correspond to the modal chromosome number. No causal relationship between changes in growth characteristics and in karyotype could be established. Comportement chez l'hǒte et caractères cytogénétiques d'un réticulo‐sarcome spontané chez le hamster doré En 2 ans et demi, 33 réticulosarcomes spontanés se sont produits dans notre colonie de hamsters dorés. L'auteur expose le comportement chez l'hǒte homologue et les caractères cytogénétiques de l'une de ces tumeurs, rendue transplantable sous forme compacte et sous forme ascitique. En 4 ans de transplantation, la tumeur a modifié son type de croissance et, après une phase initiale de croissance localisée, a présenté un mode de propagation de type leucémique entraǐnant la mort de l'hǒte le sixième ou le septième jour, quel que soit le point de transplantation. Les animaux recevant la tumeur au měme passage ont réagi différemment à l'implantation: certains ont présenté de grandes tumeurs sans diffusion des cellules, d'autres des tumeurs très petites mais avec forte dissémination cellulaire. On suppose que cette différence est li