230
J. KIRK, and J. S. ORR
Although no experimental data are available for comparison, it is necessary to examine the behaviour of the formulation when the stem cell level
is held constant. In this case, the mitotic replenishment loop is inactive, and
only the red cell loop is in operation. The red cell population was given a
small perturbation to set up oscillations. Under these conditions, periodic
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Fig. 2. Variation of cell populations with time (a, b) and the corresponding
behaviour of the mathematical formulation (c).
(--- stem cell population, ------- red cell populations, ....... reticulocyte
population)
variations are found which damp out in a similar way to those of the stem
cell mitotic loop. It thus appears clear that neither the stem cell mitotic loop
nor the red cell loop can independently maintain oscillations, and that
continued oscillations can only be maintained under conditions of interaction between the loops.