title: Oxygen consumption of single bovine embryos probed by scanning electrochemical microscopy.
abstract: Oxygen consumption of individual bovine embryos was noninvasively quantified by scanning electrochemical microscopy (SECM). A probe microelectrode was used to scan near a single embryo surface in a culture medium to monitor the oxygen reduction current at 37 degrees C, under a water-saturated atmosphere of 5% CO2 and 95% air. The oxygen concentration profiles near the embryos were in good agreement with the theoretical spherical diffusion. When an embryo reached the stage of a morula with a 74-microm radius on day 6 after in vitro fertilization, the oxygen concentration difference (deltaC) between the bulk solution and the morula surface was 6.90 +/- 1.35 microM. The oxygen consumption rate (F) of the single morula was estimated to be (1.40 +/- 0.27) x 10(-14) mol s(-1). After the SECM measurement, the embryo was continuously cultured for another 2 days and grew to the stage of a blastocyst with a 100-microm radius. For the blastocyst, the deltaC values for the inner cell mass side and the trophoblast side were 16.40 +/- 1.83 and 9.14 +/- 1.68 microM, respectively. The oxygen consumption rate of the blastocyst was found to be in the range of (2.50 +/- 0.46) x 10(-14) mol s(-1) < F < (4.49 +/- 0.50) x 10(-14) mol s(-1). We have carried out SECM measurements for 19 embryos, and the results were compared in detail with these from an optical microscopic observation. The deltaC values for the morulae on day 6 after in vitro fertilization were strongly related to the morphological embryo quality. The morulae showing a larger deltaC value developed into blastocysts of a larger size, and the deltaC value after the subsequent 2 days of cultivation was found to be increased.
authors.affiliation: Regional Joint Research Project of Yamagata Prefecture, Japan Science and Technology Corporation, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Shiku
authors.forename: T
authors.initials: T
authors.lastname: Shiraishi
authors.forename: H
authors.initials: H
authors.lastname: Ohya
authors.forename: T
authors.initials: T
authors.lastname: Matsue
authors.forename: H
authors.initials: H
authors.lastname: Abe
authors.forename: H
authors.initials: H
authors.lastname: Hoshi
authors.forename: M
authors.initials: M
authors.lastname: Kobayashi
mesh_terms: D000818:Animals; D002417:Cattle; D004563:Electrochemistry / Q000295:instrumentation; D004622:Embryo, Mammalian / Q000378:metabolism*; D020527:Microscopy, Scanning Probe; D010100:Oxygen / Q000032:analysis* / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*
chemical_list: D010100:Oxygen