But for the first heartbeats the researchers found no clear pacemakers; different embryos had different cells that started beating first and they triggered the cells around them in a wave-like pattern.

但对于第一次心， 研究员没有发现明的起搏器；不同的胚胎有不同的细胞， 它们首先开， 并以波状模式触发周围的细胞。