Abstract
Summary Experiments have been reported which show that diffusion chambers constructed of Millipore membranes of 0.45 μ average pore size can support the growth of lymphoma cells from thymus fragments and stromal cells from both normal and lym-phomatous fragments of thymus for as long as 32 weeks. Certain animals carrying chambers with tumor fragments developed lymphoma from 4-18 weeks after the chambers were implanted. It is concluded that the majority of these neoplasms probably were the result of the escape of the cells from the diffusion chambers. This conclusion is based upon the localization of tumor growth to the region near the chamber, and the short temporal relationship of tumor development to chamber implant. It is the author's opinion that migration of both normal and malignant lymphocytic cells through Millipore membranes of the mean pore size employed here remains a possibility which must be considered in all experiments of this type. Liberation of a subcellular tumorigenic agent by the viable lymphoma cells within the chambers could possibly explain the development of some of the malignancies observed.