Restoration of the T lymphoid system of nude mice: different regeneration of neonatal and adult thymuses.

When a neonatal thymus and an adult (reticuloepithelial) thymus from normal mice are simultaneously grafted to individual adult nude mice, the host-derived T cell precursors regenerate the neonatal thymus more efficiently than the adult (reticuloepithelial) thymus. Thus, this is a direct cause for the poor restoration of the T lymphoid system of nude mice by adult and/or reticuloepithelial thymus grafts.