Microinjection of rabbit hemoglobin messenger RNA into amphibian oocytes and embryos

After microinjection of hemoglobin mRNA from rabbit reticulocytes (9S mRNA) into Xenopus laevis oocytes, the cytological structure remains normal. The peroxidase reaction does not show an accumulation of synthesized hemoglobin in the germinal vesicle. Fertilized Pleurodeles Waltlii eggs synthesize rabbit hemoglobin after injection of 9S mRNA; hemoglobin synthesis decreases as development progresses. Micromeres and macromeres synthesize equal amounts of hemoglobin, despite the fact that the micromeres contain many more ribosomes. Descendants of injected blastomeres divide more slowly and do not differentiate; they ultimately undergo cytolysis.