AGE-STRUCTURED AND 2-DELAY MODELS FOR ERYTHROPOIESIS

An age-structured model is developed for erythropoiesis and is reduced to a system of threshold-type differential delay equations using the method of characteristics. Under certain assumptions, this model can b e reduced to a system of delay differential equations with two delays. The parameters in the system are estimated from experimental data, an d the model is simulated for a normal human subject following a loss o f blood. The characteristic equation of the two-delay equation is anal yzed and shown to exhibit Hopf bifurcations when the destruction rate of erythrocytes is increased. A numerical study for a rabbit with auto immune hemolytic anemia is performed and compared with experimental da ta.