Abstract
Quantitative bone marrow studies were performed in young adult rats about 60 days after extensive removal of lymph nodes. At the time of the bone marrow studies the mean content of lymph nodes in the animals corresponded to 32% of the mean lymph node content in control-operated rats. In spite of this difference in lymph node content, the lymphocyte content as well as the cell content of the other main cell groups of the bone marrow were the same in both groups of animals. This suggests that the lymph nodes are not important sites of origin of bone marrow lymphocytes.