Fig. 1

Standard length and cardiac maturation. A: The standard length (SL) of the fish as measured from snout to the base of the tail is a more meaningful measure of maturation state than zebrafish age. B: Zebrafish show a wide range of SL by age. The solid line represents mean growth while upper and lower dashed lines represent 95th and 5th percentiles size range, respectively. C,I: As the zebrafish grows, its cardiac needs grow proportionally, as seen by the linear relationship between SL and ventricle length (VL), measured from the ventricle apex to the bulboventricular junction (C) as indicated with the yellow line in (I). D-F: Maturation of zebrafish from larva (D) to juvenile (E) and finally in adulthood (F) demonstrates the changes in external features. G-I: Cardiac maturation from larva (G) to juvenile (H) and finally in adulthood (I) show not only an increase in heart size, but also changes in cardiac form. BA, bulbous arteriosus; V, ventricle; A, atrium. Scale bar = 100 μm.