The amniote embryonic heart starts as a crescent of mesoderm that transitions through a midline linear heart tube in the course of developing into the four chambered heart. It is unusual in having to contract rhythmically while still undergoing extensive morphogenetic remodeling. Advances in imaging have allowed us to determine when during development this contractile activity starts. In the mouse, focal regions of contractions can be detected as early as the cardiac crescent stage. Calcium transients, required to trigger contraction, can be detected even earlier, prior to contraction. In this review, we outline what is currently known about how this early contractile function is initiated and the impact early contractile function has on cardiac development.

中文翻译：

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第一次心跳——心脏收缩活动的起源。

羊膜胚胎心脏开始于中胚层的新月形，在发育成四腔心脏的过程中通过中线线性心管过渡。在进行广泛的形态发生重塑的同时必须有节奏地收缩是不寻常的。成像技术的进步使我们能够确定在发育过程中这种收缩活动何时开始。在小鼠中，早在心脏新月阶段就可以检测到收缩的焦点区域。触发收缩所需的钙瞬变可以在收缩之前更早地检测到。在这篇综述中，我们概述了目前已知的早期收缩功能如何启动以及早期收缩功能对心脏发育的影响。