Nucleolar and mitochondrial morphology in bovine embryos reconstructed by nuclear transfer

Autor: W.A. King, L. Plante, F. L. Barnes, M.-C. Lavoir, D.L. Shepherd, C. R. Looney
Rok vydání: 1996
Předmět:
Zdroj: Molecular Reproduction and Development. 44:499-506
ISSN: 1098-2795
1040-452X
DOI: 10.1002/(sici)1098-2795(199608)44:4<499::aid-mrd10>3.0.co;2-u
Popis: The nucleolar and mitochondrial morphology of developing reconstructed bovine nuclear transfer (NT) embryos and stage-matched in vivo-produced control embryos were examined under the electron microscope. Each reconstructed embryo at the one-cell (n = 12), two-cell (n = 5), three-cell (n = 3), four-cell (n = 5), 5–8 cell (n = 5) and blastocyst (n = 3) stages was produced by fusion of a 16–32-cell-stage blatomere with an aged enucleated bovine oocyte. The normal and reconstructed embryos showed similar mitochondrial morphology. However, NT embryos produced several pleiomorphic forms not seen in controls, and were more heterogenous at early stages of development. Control embryos exhibited nucleolar features considered indicative of rRNA synthesis from the eight-cell stage onwards. In contrast, the NT embryos presented nucleoli with morphology consistent with rRNA synthesis in all embryos examined, except in the three-cell and in two of the five four-cell embryos. From this nucleolar morphology, it was concluded that nuclear reprogramming does not occur immediately following nuclear transfer, but occurs gradually over the first two or three cell cycles. © 1996 Wiley-Liss, Inc.
Databáze: OpenAIRE
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