The application of insulin-like growth factor-I in the in vitro production (IVP) of bovine embryos
2001
Makarevic, A. | Markkula, M. (Vyskumny Ustav Zivocisnej Vyroby, Nira (Slovak Republic))
The aim of this study was to test the ability of insulin-like growth factor -I (IGF-I) to improve the development of bovine in vitro produced (IVP) embryos and to define the influence of IGF-I on the proliferation activity of embryonic cells (the presence of PCNA-positive nuclei). IGF-I, when given at high concentrations, either during oocyte maturation (100 ng/ml medium) or during zygote cleavage (50 and 500 ng/ml medium) significantly stimulated embryo cleavage and blastocyst yield. When the maturation medium in the presence of fetal calf serum was supplemented with IGF-I, the stimulating effect was more expressed than those using serum-free medium. Addition of IGF-I to serum-free medium increased blastocyst yield comparable with serum-supplemented medium without IGF-I. The addition of both IGF-I and serum together caused the additive stimulating effect on the blastocyst development. Immunocytochemical procedure combined with laser confocal microscopy demonstrated the elevation in ratio of PCNA-positive proliferating nuclei to the total cell number in embryo after IGF-I addition to the maturation medium. These results indicate, that the requirement in IGF-I is crucial both during oocyte maturation as well as during zygote cleavage and cavitation of embryos. Stimulating effect of IGF-I is associated with an increase in number of proliferating nuclei, suggesting the possibility of application of PCNA as a marker of viability and quality of IVP embryos
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