The micro-anatomy of the lymph node of germ-free piglets.

Lymph nodes from germ-free piglets were examined by conventional histological techniques. Lymph nodes of germ-free piglets draining the site of injection of carbon particles were also examined. Germinal centres were not observed in the germ-free piglets. The results are discussed and it is suggested that, although the medullary and cortical tissue are reversed in position, the lymph node of the pig does not differ fundamentally from lymph nodes in other mammalian species.