Gas exchange and development of chicken embryos with widely altered shell conductance from the beginning of incubation.
The O2 uptake of chicken embryos confined in the eggshell (MO2) is governed by a shell diffusive conductance (GO2) and PO2 difference between ambience and air space, suggesting that a relation between GO2 and air space PO2 (PAO2) is hyperbolic at constant MO2. Upon wide alteration of GO2 from the beginning of incubation, the MO2 was measured on day 16 of incubation and the relation between GO2 and PAO2 examined. The MO2 increased hyperbolically with increasing GO2, reached maximum at control conductances and decreased with further increase in GO2. From these changes in MO2 with GO2, an equation was derived predicting PAO2 as a quadratic function of inverse gO2 (mass-specific conductance, i.e., GO2 standardized by fresh egg mass), and the relation between air space PO2 and shell conductance was no longer hyperbolic. The arterialized blood PO2 (PaO2) of the allantoic vein measured individually was also expressed by a quadratic equation of inverse gO2. While for widely altered conductance the MO2 was little related to PaO2, the mass (embryo)-specific O2 uptake increased with PaO2. The excess water loss associated with increased conductance was involved in changes in these variables.
Okuda
A
A
Department of Electronic Engineering, Muroran Institute of Technology, Japan.
Tazawa
H
H
D000818:Animals; D002642:Chick Embryo / Q000502:physiology*; D004058:Diffusion; D004528:Egg Shell; D006128:Growth; D010100:Oxygen / Q000097:blood / Q000502:physiology*; D010313:Partial Pressure; D014867:Water / Q000378:metabolism; D014870:Water Loss, Insensible
D014867:Water; D010100:Oxygen