In vitro development and nutrient uptake by embryos derived from oocytes of pre-pubertal and adult cows.
The present study compared the developmental potential and uptake of nutrients by embryos from pre-pubertal and adult cows. Oocytes retrieved from ovaries of 5 to 7 month old calves and adult cows were matured and fertilized in vitro. Embryos were cultured in SOFaa to the blastocyst stage (7 days post-insemination). At successive stages of development, rates of glucose and pyruvate uptake were measured non-invasively by microfluorescence for individual embryos. Fertilization was equivalent in embryos from pre-pubertal and adult cows (P > 0.05), however development to blastocyst was significantly lower in embryos from pre-pubertal cows (9.8% versus 33.7%, respectively; P < 0.05). Total blastocyst cell number was not different between pre-pubertal and adult material (P > 0.05). Glucose uptake was exponential (pre-pubertal, r = 0.82; adult, r = 0. 82; P < 0.05), with an increase in uptake beyond the 8- to 16-cell stage. Glucose uptake was significantly lower in embryos from pre-pubertal cows at the 2- to 4-cell stages (1.5 versus 3.0 pmoles/embryo/hr; P < 0.05), but was equivalent to the adult cow at all other stages of development (P > 0.05). Pyruvate uptake was low until the blastocyst stage. Pyruvate uptake by embryos from pre-pubertal cows was significantly different to adult cows at the 1-cell stage (2.7 versus 4.6 pmoles/embryo/hr, respectively; P < 0. 05) and 2- to 4-cell stages (4.9 versus 3.6 pmoles/embryo/hr, respectively; P < 0.05). Pyruvate uptake was equivalent in the two groups in the later stages of development (P > 0.05). Perturbations in the uptake of nutrients by embryos from pre-pubertal cows were most likely due to the presence of a high proportion of developmentally incompetent embryos. Further, embryos from pre-pubertal cows that did develop to the blastocyst were as viable as blastocysts from adult cows with respect to nutrient uptakes and total cell number.
Steeves
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Centre for Early Human Development, Institute of Reproduction and Development, Monash Medical Centre, Clayton, Victoria, Australia. Tracey.Steeves@med.monash.edu.au
Gardner
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DK
Zuelke
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KA
Squires
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TS
Fry
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RC
D000818:Animals; D001755:Blastocyst / Q000378:metabolism; D002417:Cattle; D002452:Cell Count; D002470:Cell Survival; D002478:Cells, Cultured; D004622:Embryo, Mammalian / Q000378:metabolism*; D005314:Embryonic and Fetal Development; D005260:Female; D005307:Fertilization in Vitro; D005947:Glucose / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism*; D019289:Pyruvic Acid / Q000378:metabolism
D019289:Pyruvic Acid; D005947:Glucose