Collection of lymph from single lymph nodes and the intestines of fetal lambs in utero.

Techniques for establishing chronic lymphatic fistulae in the intestinal and prescapular lymphatic ducts of fetal lambs during the test third of gestation are described. Despite the absence of antibody, immunoglobulin and extrinsic antigen, the number of recirculating lymphocytes increases considerably through gestation. Both thymus-derived and surface Ig-bearing B lymphocytes are present in the fetal recirculating pool and they appear to increase in number at the same rate.