Gas exchange by embryos from chickens acclimatized to an altitude of 3800 m (pB = 480 torr) was studied in order to ascertain the nature of the altitude adaptation in this species. The PO2 and PCO2 differences across the egg shell were measured and found to be less than the values previously reported for sea-level eggs by about a factor of two. Further measurements of embryonic oxygen consumption (O2) and shell conductivity to oxygen (GO2) indicated that, compared to eggs at sea level, O2 was reduced by a factor of 0.58 while GO2 was increased only by a factor of 1.07 in the high-altitude eggs. These independent measurements predict the ΔPO2 across the egg shell of the high-altitude eggs to be only 0.54 times that of sea-level eggs; the directly measured factor was 0.53. The authors conclude that at high altitude a major adaptation of the chick embryo is a reduced metabolism which decreases the ΔPO2 across the egg shell since its gas conductivity remains essentially unchanged.
Bibliographical noteFunding Information:
Accepted for publication 5 March 1974. * These studies were carried out at the White Mountain Research Station operated by the University of California, Director Dr. Nello Pace, University of California at Berkeley. The White Mountain chicken colony has been supported by grants from the United States Public Health Service (HE-01920) and NASA (NGR 05-004-008) to the University of California at Davis. The present study was supported in part from the Institutional Funds Committee, Faculty of Health and Sciences, State University of New York at Buffalo, New York. ** 0. D. Wangensteen’s present address is Department of Physiology, 424 Millard Hall, University of Minnesota, Minneapolis, Minnesota 55455, U.S.A. *** R. R. Burton’s present address is USAF School of Aerospace Medicine, SMB, Brooks Air Force Base, Texas 78235, U.S.A.
- Air-cell O and CO
- Chick embryo
- Diffusion coefficient
- Egg shell porosity