Abstract
Summary
Radioactive ethionine is present in the soluble fraction and in the proteins of the rat fetus and placenta within 5 minutes after injection on day 12 of pregnancy. The maximum amount of soluble activity is found in the placenta within 15 minutes after injection and not until 2 hours in the fetus and amniotic fluid. The maximum amount of protein-bound label is present in the conceptus 12 hours after injection. Auto-radiography studies show the presence of diffuse radioactivity throughout the conceptus within 5 minutes after injection of ethionine, which persists up to 72 hours after injection. There is a possible concentration of the label in or adhering to the maternal and fetal erythrocytes at all times after injection of labeled ethionine.
The authors wish to express their appreciation to Dr. C. A. Woolever for use of the Packard Tri-Carb liquid scintillation system, to Mrs. Barbara D. Fleischaker and Miss Juanita Graves for technical assistance, and to Dr. S. W. Smith for suggestions on autoradiography.
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