Table 1.

Timings of major events in heart development.

Human(days)	Mouse(E)	Chick (HH (days))	Zebrafish (hpf)	Major events in heart development
15	7.5	7 (1)	17.5	Cardiac crescent
21–22	8.5	8–9 (1.3)	18–19.5	Fusion of paired heart tubes
22	8.5	10 (1.5)	22	First myocardial contractions
22	8.5	9–10 (1.5)	30	Cardiac looping initiates
24	8.5	10 (1.5)	24	First blood flow through the heart
26	9.5	16–17 (2.5)	48	Ventricular trabeculation starts
28	9.5	12–13 (2)	60	First definable endocardial cushions
56	12.5	21–23 (3.5–4)	105	Appearance of primordial atrioventricular valves
56	12.5	28–29 (5.5–6)		Appearance of primordial semilunar valves
48–56	10.5–13.5	16–46 (2–21)		Atrial septation
52–56	11.5–13.5	25–34 (4.5–8)		Outflow tract septation
52–64	11.5–13.5	19–34 (3–8)		Ventricular septation

Comparison among human, mouse, chick and zebrafish; the latter three are frequently used as models of heart development. Human staging is given in days, mouse staging in embryonic day (E), chick staging in Hamburger-Hamilton staging (HH)(Hamburger and Hamilton, 1992) and approximate days of incubation, and zebrafish staging in hours post fertilization (hpf).

Note: The zebrafish heart has a single atrium and ventricle thus some aspects of heart morphogenesis differ from those of human, mouse and chicken. Adapted from (Lindsey et al., 2014)with additional data from (Stainier et al., 1993; Hu et al., 2000; Beis et al., 2005; Martinsen, 2005; Martinsen and Lohr, 2005; Martin and Bartman, 2009; Krishnan et al., 2014; Captur et al., 2016).