[Heart growth in the human embryonic period (a study related to the 2d month of gestation)].

The growth of the heart was studied in 27 human staged embryos of post-somitic period (stages from 15 to 23, Carnegie Institution of Washington). The volume of the heart was determined multiplying the cardiac profiles areas (evaluated by point counting planimetry on serial sections) by the thickness of microtomy. Cardiac volume increase was examined relative to age, to crownrump length, and to body weight. The data were transformed into logarithms and bivariate relations were analysed according allometric equations of the form (log y = k log x + log b). The data were fitted according to three techniques: least squares, major axis, and reduced major axis. The slopes of the allometric regressions indicate positive allometry of the cardiac volume relative to embryonic age and to C-R length, and isometry relative to body weight.