Nucleolar and mitochondrial morphology in bovine embryos reconstructed by nuclear transfer.
Mol Reprod Dev
; 44(4): 499-506, 1996 Aug.
Article
em En
| MEDLINE
| ID: mdl-8844693
ABSTRACT
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 heterogeneous 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.
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Base de dados:
MEDLINE
Assunto principal:
Nucléolo Celular
/
Embrião de Mamíferos
/
Técnicas de Transferência Nuclear
/
Mitocôndrias
Limite:
Animals
Idioma:
En
Revista:
Mol Reprod Dev
Ano de publicação:
1996
Tipo de documento:
Article