Ever wondered how the heart gets its distinguishing shape? Shape may be formed by cell movement, cell division, or alterations in cell size and shape, all of which react to influences from the local environment. Initially, the heart is an uncomplicated tube that bulges later on to develop into cardiac chambers.
In a new study published online in the open access journal PLoS Biology, Heidi Auman, Deborah Yelon, and colleagues found, by using transgenic zebrafish in which they can watch individual cardiac cells, that cells change size and shape, enlarging and elongating to form the bulges in the heart tube and eventually the chambers. Since the heart is beating as it develops, they asked whether cardiac function influences cell shape. Using zebrafish mutants with functional defects, they found that both blood flow and cardiac contractility influence cardiac cell shape. The researchers propose that a balance of the cell's internal forces (through contractility) with external forces (such as blood flow) is necessary to create the cell shapes that generate chamber curvatures. Disruption of this balance may underlie the aberrations observed in some types of heart disease.