Under hypoxic conditions, angiogenesis in the chorioallantoic membrane exhibits a sensitive response depending on the developmental timing and intensity and duration of the hypoxia. Furthermore, the effects of hypoxia on vascularization in the chorioallantoic membrane are controversial. In this study, we used microscopy to determine the vascular density index of chicken embryonic chorioallantoic membrane and quantitative PCR to examine the expression of the HIF-1α and VEGFA genes. Two levels of hypoxia (15% and 13% O2) and three durations (days 0–10, 11–18, and 0–18) were applied. The results showed that 13% O2 incubation restrained angiogenesis in the chorioallantoic membrane at an early stage of embryonic development as seen on day 6, but incubation under 13% or 15% O2 efficiently stimulated vascularization of the chorioallantoic membrane as seen on days 16 and 18. Notably, 13% O2 incubation caused visible curling of the blood vessels in the chorioallantoic membrane on day 18. The increased vascular density index under hypoxia was accompanied by an increase in the expression of VEGFA and HIF-1α. Curled blood vessels were observed on day 18 under 13% O2 incubation; however, the curling was not a result of VEGFA overexpression. Thus, the present study helps in elucidating vascularization of the chorioallantoic membrane under hypoxic conditions.
Regional hypoxia elicits regional changes in chorioallantoic membrane vascular density in alligator but not chicken embryos.
Comp. Biochem. Physiol. A Mol. Integr. Physiol.12557-61.
A novel role for VEGF in endocardial cushion formation and its potential contribution to congenital heart defects.
Angiogenesis in a human neuroblastoma xenograft model: mechanisms and inhibition by tumour-derived interferon-γ.
Br. J. Cancer941845-1852.
RouwetE.V.TintuA.N.SchellingsM.Van BilsenM.LutgensE.HofstraL.SlaafD.W.RamsayG.Le NobleF. (2002)
Hypoxia induces aortic hypertrophic growth, left ventricular dysfunction, and sympathetic hyperinnervation of peripheral arteries in the chick embryo.
The gaseous environment of the chick embryo in relation to its development to and hatchability. 2. Effects of carbon dioxide and oxygen levels during the period of the fifth through the eighth days of incubation.
The gaseous environment of the chick embryo in relation to its development to and hatchability. 3. Effects of carbon dioxide and oxygen levels during the period of the ninth through the twelfth days of incubation.