We consider a steady-state non-linear boundary value problem which arises i
n modelling the formation of vascular networks in response to tumour growth
. Global bifurcation from both trivial and non-trivial solution branches is
considered, with emphasis on the latter. By investigating such secondary b
ifurcation, it is shown that positive, bounded solutions exist for all phys
ically relevant values of a critical parameter. A certain class of these so
lutions is discussed with respect to the application to tumour growth. (C)
1999 Academic Press.