A simple method for forming embryoid body from mouse embryonic stem cells.

We proposed a simple method for forming an embryoid body (EB) from mouse embryonic stem (ES) cells using a polypropylene 1.5-ml conical tube with a screw cap. An ES cell suspension containing 2 x 10(4) cells was incubated in a conical tube. After 5 d of incubation, a single EB of 440 microm average diameter was formed in the conical tube. The formation efficiency of EB, which is the ratio of the number of tubes showing EB formation to the number of tubes seeded with ES cells, was greater than 99% in the conical tube, while it was approximately 60% in a hanging drop culture. The 5-day-old EB formed by the conical tube method had a sufficient differentiation ability. The beating of the cardiac muscle was microscopically observed in the populations derived from the 5-day-old EB.