Neonatal thymus grafts. II. Cellular events.

Neonatal thymus undergoes sequential necrosis and cell regeneration after grafting under the kidney capsule in normal and thymectomized recipients. This regeneration assessed in terms of cell number, response to mitogens, in vivo steroid sensitivity, level of antigen-binding cells, and cellular distribution on Ficoll gradient is not influenced by the presence of host thymus or by FTS injections. The grafted thymus shows a similar pattern of development as control thymus of the same age followed up in situ, with the exception of age-related involution the onset of which takes place earlier in the grafted thymus.