Ontogeny of J chain expression in pig lymphocytes

The ontogeny of lymphocytes expressing J chain in the cytoplasm (J +) was studied in pig foetuses by the immunofluorescent technique. Peripheral blood lymphocytes were the first J + cells in prenatal life. The spleen and lymph nodes contained J + cells in the last days of gestation. J + cells were found in the lamina propria of the gut and some glands of conventional but not of germ-free piglets. J chain was not detected on or in cell membranes at any developmental stage.