Isotopic labeling of embryo, yolk sac, and intracellular parasites of the embryonated hen's egg by yolk replacement.

A technique is described which allows the replacement of 50% of the yolk of the embryonated hen's egg with large volumes of diverse but chemically defined solutions. By using an electrosurgical unit and a polyethylene tunnel, the procedure was performed on eggs from days 3 through 7 with greater than 90% surgical success and viability for the short term. More than 50% of the eggs replaced showed viability for 2 weeks, and a significant proportion went full term. (32)PO(4) and amino acids ((3)H and (14)C) added to the replaced eggs were incorporated into the macromolecules of the embryo and yolk sac as well as into parasitic rickettsiae cultivated in the replaced eggs. The incorporated (32)PO(4) was shown to be assimilated into a variety of biochemical species.