The heart is at first placed within the body cavity attached to the ventral wall of the gut by a mesocardium (fig. 353 A).
mesocardium mes·o·car·di·um (měz'ə-kär'dē-əm, měs'-)
n. pl. mes·o·car·di·a (-dē-ə)
Either of the two layers of the embryonic mesentery supporting the embryonic heart in the pericardial cavity.
