Tb. Corona et Sj. Warburton, Regional hypoxia elicits regional changes in chorioallantoic membrane vascular density in alligator but not chicken embryos, COMP BIOC A, 125(1), 2000, pp. 57-61
Citations number
16
Categorie Soggetti
Animal Sciences",Physiology
Journal title
COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY A-MOLECULAR AND INTEGRATIVE PHYSIOLOGY
Hypoxic incubation increases vascularization in the chick chorioallantoic m
embrane (CAM). The effect of regional hypoxia on the vascular density of Am
erican alligator (Alligator mississippiensis) and chicken (Gallus gallus) C
AMs was studied to determine if hypoxic proliferation of blood vessels is l
ocalized or global across the CAM. Eggs were incubated under normoxic condi
tions with a portion of the eggshell covered with non-toxic beeswax to indu
ce external regional hypoxia. CAMs were examined under a microscope with a
'bulls eye' coverslip and a vascular density index (VDI) was determined. Th
e hypoxic portions of the alligator CAMs were more vascular than the normox
ic portions (VDI = 200.9 versus 157.8, respectively). Presumably this respo
nse is maladaptive by causing increased blood flow to the poorly oxygenated
portions, i.e. increased 'shunt'. Thus, we hypothesize increased vasculari
ty due to hypoxic incubation is due to local release and subsequent rapid l
ocal breakdown or uptake of angiogenic factors. In contrast, the hypoxic an
d normoxic portions of the chick CAMs exhibited virtually no difference in
VDI (VDI = 211.5 versus 217.9, respectively). We suggest the air cell and a
ir space of the chicken eggs allows for circulation of gas in ovo, eliminat
ing the possibility of regional internal hypoxia. (C) 2000 Elsevier Science
Inc. All rights reserved.