TNP-Ficoll response in Xenopus laevis: substitution and reconstitution in thymectomized animals.

The capacity to respond to haptenated Ficoll, though thymus-independent in mammals, is lost in Xenopus laevis following thymectomy at any stage of development. This capacity can be restored to thymectomized Xenopus by whole allogeneic thymus implants, by thymus implants from animals treated with N-methyl-N-nitrosourea (which have an active thymus medulla but no cortex, and which lack certain thymus-dependent immunological functions), and Concanavalin A. These results are discussed in terms of the cell populations and/or factors which may be involved.