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Science 5 March 1971:
Vol. 171. no. 3974, pp. 898 - 901
DOI: 10.1126/science.171.3974.898
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Articles

Ribosomal RNA Synthesis and the Multiple, Atypical Nucleoli in Cleaving Embryos

Charles P. Emerson Jr. 1 and Tom Humphreys 1

1 Department of Biology, University of California, San Diego, La Jolla 92037

The rate of ribosomal RNA synthesis per nucleus in cleaving sea urchin embryos is similar to the rate at later embryonic stages. The multiple, atypical nucleoli, present in early embryos and usually attributed to decreased ribosomal RNA synthesis, are beginning stages of nucleolar formation. Full nucleolar development requires more time than the brief interphase of the rapidly dividing cells.

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Science. ISSN 0036-8075 (print), 1095-9203 (online)