title: Identification of marrow-derived and thymus-derived small lymphocytes in the lymphoid tissue and thoracic duct lymph of normal rats.
abstract: These experiments show that small lymphocytes from the thoracic duct of rats are normally a mixture of thymus-derived and marrow-derived cells, and define the traffic areas in lymphoid tissues through which the two populations recirculate. Thoracic duct lymphocytes were labeled in vitro with uridine-(3)H and their histological distribution in the lymphoid tissues of normal recipients was demonstrated by radioautography. Labeled lymphocytes occupied two adjacent areas distinguished by a marked difference in the intensity of labeling; heavily labeled cells were found in thymus-dependent traffic areas of lymphocyte recirculation, while lightly labeled cells localized in the thymus-independent follicular areas around germinal centers. A corresponding heterogeneity of uridine uptake among small lymphocytes from normal donors was demonstrated by sedimentation at 1 g; slowly sedimenting cells incorporated little uridine and localized in follicular areas after transfusion while rapidly sedimenting cells incorporated more uridine and localized in thymus-dependent areas after transfusion. Experimentally prepared marrow-derived small lymphocytes behaved in sedimentation studies and after transfusion like a pure population of the lightly labeled small lymphocytes in normal lymph. Artificially reconstituted mixtures of marrow-derived and thymus-derived lymphocytes were qualitatively indistinguishable from normal lymphocyte populations.
mesh_terms: D000818:Animals; D000921:Antibody-Producing Cells; D001345:Autoradiography; D001775:Blood Circulation; D001799:Blood Sedimentation; D001853:Bone Marrow; D001854:Bone Marrow Cells; D007082:Ileum / Q000166:cytology; D007275:Injections, Intravenous; D008196:Lymph / Q000166:cytology*; D008198:Lymph Nodes / Q000166:cytology; D008214:Lymphocytes; D008221:Lymphoid Tissue / Q000166:cytology; D011828:Radiation Chimera; D051381:Rats; D011919:Rats, Inbred Strains; D013154:Spleen / Q000166:cytology; D013897:Thoracic Duct / Q000166:cytology; D013950:Thymus Gland / Q000166:cytology*; D014316:Tritium; D014529:Uridine / Q000378:metabolism
chemical_list: D014316:Tritium; D014529:Uridine