Influence of Thymic Mass on Murine Viral Leukaemogenesis

Abstract

THE origin of lymphoma in the thymuses of mice is now well documented¹. Of interest is the fact that regardless of the means used to induce the lymphoma (virus, chemicals, hormones, X-rays), the pattern of the thymic response is always similar. Recently, in pathogenesis investigations of a virus-induced lymphoma, attention was directed to the thymic anatomy. It was demonstrated that the two ‘lobes’ of ‘the thymus’ actually are two separate, paired organs^2–4. This was of interest because it was noted that the lymphoma change occurred in only one of the two thymuses. Tumour cells frequently disseminated from a tumour-transformed thymus at a time when the opposite thymus was still histologically normal. The process of tumour formation studied histologically in serial sections suggested that the tumour cells evolved throughout a single thymus rather than at a single point³. Regarding the thymuses as organs which provide the site for the lymphoma evolution⁵, it was of interest to investigate the anatomic unit of thymic tissue necessary for such a change.