Migration into pseudo-follicles of draining lymph nodes of medullary small thymocytes injected in the mediastinal cavity.
Maneno muhimu
Kikemikali
After an intramediastinal injection of labelled thymic cells, few cells were found in the pseudo-follicles of the draining nodes while the extrafollicular zone of their cortex contained abundant labelled cells (Sainte-Marie and Peng, in press). We proposed that the cells having migrated into the pseudo-follicles were small lymphocytes of the thymic medulla, or medullary small thymocytes, which accounts for about 5% of the thymocyte population. The purpose of the present study was to test the validity of the proposal. Rats received corticosterone injections to destroy, their cortical thymocytes and, thereafter, a dose of 3H-cytidine in order to label the surviving medullary small thymocytes. One hour later, these cells were suspended and injected in the mediastinal cavity of recipients which were killed 3 and 24 hours after the injection. The radio-autographs of the draining, and of the remaining, nodes revealed that most labelled cells, present in the nodes at the 24-hour interval, were situated mostly in the pseudo-follicles. The finding indicates, that, unlike the cortical small thymocytes, the medullary small thymocytes can migrate into pseudo-follicles. This is probably due to the greater motility of the medullary small thymocytes and possibly, to their involvement in the function(s) carried out in the pseudo-follicles.