Differentiation of mouse thymus cultured in diffusion chambers.

Abstract

AbstractConsiderable evidence has been brought forward in recent years to show that thymus growing in intraperitoneally implanted diffusion chambers will partially restore immunological competence to mice thymectomized at birth (Osoba and Miller, '63); Levey, Trainen and Law, '63; Law, Trainen, Levey and Barth, '64; Law, Dunn, Trainen, and Levey, '64; Osoba, ('65). Since it was suggested that the thymus cells secrete a factor that mediates the restoration, it was of interest to examine the thymic cells that grew or survived in the diffusion chamber. Whole thymuses from new‐born mice were grown in thymectomized or intact, syngeneic or allogeneic hosts of various ages. Whole‐mount preparations were made of the thymus tissue after it had grown for from 9‐‐86 days. Thymic lymphocytes, granulocytes, macrophages and fibroblasts migrated rapidly from the explant, the latter forming a sheet that covered the entire chamber. Viable lymphocytes were present in chambers removed from the host after 86 days. The striking feature of the cultures was the differentiation of the epithelium into sheets, clusters, and cords of cells reminiscent of glandular epithelium. Whorls of cells resembling Hassall's bodies were occasionally seen. These epithelial cells were distinguished by the presence of large lipid‐filled vacuoles and neutral mucopolysaccharide in the cytoplasm. It is suggested that the epithelial cells were engaged in secretory activity.