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Chronological Appearance of Apoptosis in Bovine Embryos Reconstructed by Somatic Cell Nuclear Transfer from Quiescent Granulosa Cells
Author(s) -
Gjørret JO,
Wengle J,
MaddoxHyttel P,
King WA
Publication year - 2005
Publication title -
reproduction in domestic animals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.546
H-Index - 66
eISSN - 1439-0531
pISSN - 0936-6768
DOI - 10.1111/j.1439-0531.2005.00578.x
Subject(s) - blastocyst , embryo , biology , somatic cell nuclear transfer , tunel assay , somatic cell , apoptosis , andrology , embryonic stem cell , programmed cell death , embryogenesis , microbiology and biotechnology , genetics , gene , medicine
Contents Efficiency of cloning has remained low and in spite of attempts to improve this technology, many reconstructed embryos do not implant or are lost during early pregnancy. Chromosomal aberrations, deviant gene expression patterns and abnormal regulation of cell death may be involved in this increased early embryonic loss. Here, we investigate the chronological onset of both apoptotic changes in nuclear morphology and DNA degradation [detected by transferase‐mediated dUTP nick‐end labelling (TUNEL) reaction] in bovine two‐cell‐ to blastocyst‐stage embryos. Such embryos were generated either by reconstruction with nuclear transfer from quiescent granulosa cells or by regular in vitro embryo production. Nuclear condensation was observed from the two‐cell stage and TUNEL labelling was observed from the six‐cell stage in reconstructed embryos, whereas nuclear condensation was evident from the eight‐cell stage and TUNEL labelling from the 13‐cell stage in embryos derived in vitro . Furthermore, reconstructed embryos displayed elevated ratios of embryos containing apoptotic nuclei at pre‐compaction stages and higher indices of apoptotic nuclei in morula and blastocyst stages when compared with in vitro ‐produced embryos.