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Morphology as a Tool in Embryo Technology
Author(s) -
MaddoxHyttel P.
Publication year - 2005
Publication title -
anatomia, histologia, embryologia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.34
H-Index - 35
eISSN - 1439-0264
pISSN - 0340-2096
DOI - 10.1111/j.1439-0264.2005.00669_49.x
Subject(s) - inner cell mass , biology , blastocyst , embryo , population , embryo culture , microbiology and biotechnology , somatic cell nuclear transfer , zona pellucida , embryogenesis , oocyte , demography , sociology
The increased use of embryo technologies, in particular in cattle, has emphasized the need for assessing embryo quality by morphological techniques, such as transmission electron microscopy, immunohistochemistry, immunocytochemistry for confocal laser scanning microscopy, and fluorescence in situ hybridization. By a combination of these techniques, we have demonstrated that (1) the rRNA gene activation in the 8‐cell bovine embryo as monitored by nucleolar development is comparable in embryos developed in vivo and produced in vitro , whereas embryos reconstructed by cloning by nuclear transfer display deviations in nucleolar development, (2) generating bovine embryos by in vitro production and reconstruction by nuclear transfer is associated with increased occurrence of apoptosis, in particular in the inner cell mass of the blastocyst, (3) the same two embryo production techniques are associated with increased occurrence of mixoplody, i.e. embryos presenting a major population of normal diploid cells and a minor population of abnormal haploid or polyploid cells, and (4) upon hatching from the zona pellucida , the inner cell mass of the bovine blastocyst differentiate into hypoblasts and epiblasts, the latter of which forms a laminin enclosed pluripotent cell niche staining positive for the pluripotent transcription factor Oct‐4; a morphology that resembles that maintained by bovine ES‐like cells cultured through several passages in vitro .