Splenic autotransplantation in nude mice. The formation of white pulp.

Splenic fragments were autotransplanted into the greater omentum of nude mice (nu/nu) and normal mice to investigate the formation of white pulp in splenic regeneration. The formation of white pulp began from day 5 after transplantation in both groups. Two patterns were found. In one pattern, follicles containing only B cells were first formed and developed into white pulp with poorly developed periarterial lymphoid sheaths (PALS). Most of the white pulp in nude mice and about one third of white pulp formed at day 28 in normal mice followed this pattern. In the second pattern, PALS were first formed and afterwards follicles appeared in the periphery of PALS. This was mainly seen in normal mice. Thus splenic autografts in normal mice contain white pulp with poorly developed PALS, and the homing of T cells begins later than that of B cells. This suggests the possibility of incomplete cellular immunity.