Embryological basis for cardiac left–right asymmetry

Abstract

Asymmetric heart tube looping and chamber morphogenesis is a complex process that is just beginning to be understood at the genetic level. Rightward looping is the first embryological manifestation of consistently oriented, left–right asymmetric development of nearly all visceral organs. Intuitively, invariant anatomical asymmetry must derive from a novel mechanism capable of integrating dorsoventral and anteroposterior information. The details of this process are emerging for several vertebrates and reveal that overall left–right asymmetry, once polarized with respect to dorsoventral and anteroposterior axes, unfolds through distinct left- and right-sided programs of gene expression. These, in turn, regulate expression of cardiac and chamber-specific genes which guide heart morphogenesis and differentiation