Blood Chemistry of the Chick Embryo During Ontogenesis

Abstract

Within the last few years increasing attention has been given to studies concerning the changes in the concentration of a number of blood constituents during prenatal development. With the aid of such data it may be possible to add further information concerning the utilization of the various foodstuffs during the embryonic period. Further, it may be possible, by correlating the extent of functional development of the various organs of the embryo at a given age with such chemical blood data, to throw further light upon the influence of a given organ upon intermediary metabolism.

The chick embryo was chosen as the experimental animal. The eggs were incubated under standard conditions and at the desired age the egg was carefully opened and sufficient blood for analysis was withdrawn from the vitelline artery or vein into a 1 cc. tuberculin syringe. Since satisfactory blood samples could not be obtained from embryos of less than 9 days incubation no analyses were attempted until that time. From this period on, however, the analyses were carried on through the entire incubation period and for several days after hatching.

Table I presents the results of the average daily changes occurring in the several constituents of the blood during the course of ontogenetic development. The numbers in parentheses indicate the number of separate analyses from different embryos used to compute the average. From these results it is observed that the embryonic blood sugar is increased beginning with the 16th day of incubation. The increase in the uric acid concentration is observed much earlier in the developmental period. Similar increases are observed in the concentration of cholesterol and hemoglobin, and in red blood cell counts, with the exception of a definitely lowered level during the hatching period.