Growth, development, and gene expression by in vivo- and in vitro-produced day 7 and 16 bovine embryos.

The effects of the embryo production system on growth and transcription rate of day 7 and 16 bovine embryos were investigated. In vivo- (controls) and in vitro-produced (IVP) embryos were transferred to female recipients on day 7 of development, and were allowed to develop in a synchronous uterine environment to day 16. Embryonic transcripts for insulin-like growth factors-1 and -2 (IGF-1 and -2), their receptors (IGF-1r and -2r), facilitative glucose transporters-1 and -3 (Glut-1 and -3), and interferon-tau (IFN-tau) were determined by real-time quantitative PCR (TaqMan); gender diagnosis was performed on day 16 concepti only. On day 7, IVP embryos presented lower mRNA levels than controls (P < 0.05), but these differences were generally reduced on day 16. No IGF-1 transcripts were detected on day 7, but a low IGF-1 mRNA level was observed in day 16 embryos. In the IVP group, IFN-tau mRNA levels were lower on day 7 (P < 0.05), but higher than controls on day 16 (P < 0.05). Control embryos showed a temporal decrease in the relative transcription from day 7 to 16 (P < 0.05), except IGF-1 mRNA. On day 16, IVP concepti were shorter and displayed smaller embryonic discs (P < 0.05). Female concepti were generally smaller than males, and IGF-2r mRNA and growth were negatively correlated. The in vitro production of bovine embryos negatively affected the amount of gene expression on day 7 and the rate of development on day 16. Physical traits and transcriptional activity on day 16 were associated with one another, which appeared to be significant for growth and development.

Morphology and morphometry of in vivo- and in vitro-produced bovine concepti from early pregnancy to term and association with high birth weights.

This study was designed to characterize conceptus development based on pre- and postnatal measurements of in vivo- and in vitro-derived bovine pregnancies. In vivo-produced embryos were obtained after superovulation, whereas in vitro-produced embryos were derived from established procedures for bovine IVM, IVF and IVC. Blastocysts were transferred to recipients to obtain pregnancies of single (in vivo/singleton or in vitro/singleton groups) or twin fetuses (in vitro/twins group). Ultrasonographic examinations were performed weekly, from Day 30 of gestation through term. Videotaped images were digitized, and still-frames were used for the measurement of conceptus traits. Calves and fetal membranes (FM) were examined and measured upon delivery. In vitro-produced fetuses were smaller than in vivo controls (P < 0.05) during early pregnancy (Day 37 to Day 58), but in vitro/singletons presented significantly higher weights at birth than in vivo/control and in vitro/twin calves (P < 0.05). From late first trimester of pregnancy (Day 72 to Day 93), placentomes surrounding in vitro-derived singleton fetuses were longer and thinner than controls (P < 0.05). At term, the presence of giant cotyledons in the fetal membranes in the in vitro group was associated with a larger cotyledonary surface area in the fetal horn (P < 0.05). The biphasic growth pattern seen in in vitro-produced pregnancies was characterized by conceptus growth retardation during early pregnancy, followed by changes in the development of the placental tissue. Resulting high birth weights may be a consequence of aberrant placental development due to the disruption of the placental restraint on fetal growth toward the end of pregnancy.