Respiration activity of single bovine embryos entrapped in a cone-shaped microwell monitored by scanning electrochemical microscopy

The respiration activity of single bovine embryos entrapped in a cone-shaped microwell was monitored by scanning electrochemical microscopy (SECM). A measuring cell composed of six cone-shaped microwells was employed. The height and radius of the cone-shaped microwell were both 2 mm. Individual embryos were located in either a culture dish or the microwell to compare the oxygen concentration gradients of the surrounding medium solution at 37 °C in a watersaturated atmosphere of 5% CO2 and 95% air. The oxygen concentration profile of the embryo located on the flat bottom of the culture dish is well described by the spherical diffusion theory. When the embryo was transferred into the cone-shaped microwell, the concentration profile changed. To analyze the diffusion behavior of the embryo in the microwell, a sphere whose center is located at the top of the cone was appropriate rather than one whose center is located at the sample center. The oxygen consumption rate of the embryo in the microwell was found to be 0.7 fold of that in the culture dish.