D. Ribatti et al., ENDOGENOUS BASIC FIBROBLAST GROWTH-FACTOR IS IMPLICATED IN THE VASCULARIZATION OF THE CHICK-EMBRYO CHORIOALLANTOIC MEMBRANE, Developmental biology, 170(1), 1995, pp. 39-49
Chorioallantoic membrane (CAM) and chorioallantoic fluid (CAF) of the
chick embryo were studied for the presence of immunoreactive and biolo
gically active basic fibroblast growth factor (bFGF) from Day 6 to Day
18 of incubation. An immunoreactive M(r) 16,000 bFGF-like molecule wa
s detected both in CAM and in CAF. This molecule was identified as bFG
F on the basis of its molecular weight, its affinity for heparin, and
its capacity to induce plasminogen activator production in cultured en
dothelial GM 7373 cells. The levels of biologically active and immunor
eactive bFGF vary in CAM and CAF during embryonic development, maximal
concentrations being observed between Days 10 and 14 of incubation. A
t all time points investigated, absolute concentrations of bFGF were s
ignificantly higher in CAM (ranging from 25 to 183 ng/g of wet tissue)
than in CAF (ranging from 0.2 to 4 ng/ml). In a parallel series of ex
periments performed at Day 8 and evaluated at Day 12 of chick embryo d
evelopment, human recombinant bFGF and neutralizing anti-bFGF antibody
were investigated for their capacity to affect the vasoproliferative
processes of the CAM. The two molecules either were applied onto the s
urface of the CAM or were injected into the allantoic sac. When bFGF o
r anti-bFGF antibodies were absorbed on methylcellulose discs and appl
ied on the top of the CAM, they exerted a strong angiogenic or anti-an
giogenic effect, respectively. On the contrary, when bFGF or the corre
sponding neutralizing antibody was injected into the allantoic sac, no
modidcations of the vasoproliferative processes of the CAM were obser
ved at either the macroscopic or the microscopic level. These results
provide evidence indicating that endogenous bFGF has a rate-limiting r
ole in the vascularization of the CAM during chick embryogenesis. bFGF
located within the CAM, rather than that present in the CAF, appears
to be involved in this developmental process. (C) 1995 Academic Press,
Inc.