Thymus‐derived lymphocytes: their distribution and role in the development of peripheral lymphoid tissues of the mouse

Abstract

Abstract Using the theta (Θ) alloantigen of mice as a marker of thymus‐derived cells, we have studied the distribution of these lymphocytes in adult and developing lymphoid tissues of CBA and Balb/c mice. In adult mice, lymphoid tissues can be arranged in the following order according to the approximate proportions of Θ‐bearing (thymus‐derived) lymphocytes they contain: thymus (100%), thoracic duct lymphocytes (80–85%), blood lymphocytes (70%), lymph nodes (65–70%), spleen (30–35%), peritoneal lymphocytes (30–35%) and Peyer's patches (20–25%). Results obtained in newborn mice show that the development of peripheral lymphoid tissues is largely dependent on the inflow (and possibly the proliferation) of thymus‐derived lymphocytes. The presence of Θ‐bearing lymphocytes in developing Peyer's patches indicates that lymphoid differentiation in these organs is, in part at least, thymus‐dependent.