Kinetics of the distribution of thymus and marrow cells in the peripheral lymphoid organs of the mouse: ecotaxis.

Abstract

The differences between the fate of mouse thymus and marrow cells labelled in vitro with [3H]adenosine following intravenous injection into syngeneic recipients are defined. Thymus cells home predominantly to the thymus–dependent territory in the recipient's peripheral lymphoid organs, whereas the majority of bone marrow cells is found in thymus–independent sites. In addition, it is shown that a marrow inoculum contains a variety of sub-populations able to discriminate microenvironmental differences within the thymus–independent territory itself. In general, cell populations behave as if they have the ability to distinguish and home towards what is probably their usual environment. The word `ecotaxis' is offered to define this phenomenon, and the mechanisms that may be involved in determining it are discussed.