Red cell egress from the marrow: ? vis-à-tergo

The egress of red cells from the marrow requires their translocation from the hemopoetic space into the marrow sinus lumen. The force for this translocation may be derived from a pressure drop that exists across the marrow sinus wall. Modeling suggests that a pressure gradient of the magnitude estimated to be present in the marrow could drive cells rapidly through pores in the sinus endothelium.