Functional and morphological changes in post-capillary venules in relation to lymphocytic infiltration into BCG-induced granulomata in rat skin.

Vessels identical to lymph node high endothelial venules (HEV) have been described in sites of non-lymphoid tissue lymphocyte accumulation. In this study the function of these (HEV-like) vessels has been investigated in BCG-induced skin lesions in the rat. By following the traffic of radiolabelled lymphocytes from the blood into the lesions the HEV-like vessels have been shown to be the preferred site of migration. The complicated development of the vessels has been studied and an hypothesis advanced to explain their inter-relationship with tissue and circulating lymphocytes.