Sexually dimorphic ontogenetic trajectories of frontal sinus cross sections.

In this paper, we analyze a large published data set of cross sections of frontal sinuses of 3 to 11-year-olds (105 males and 87 females) from Central Europe to investigate several issues relating to frontal sinus ontogeny. Despite a large variation in every one year age cohort, we detect no asymmetry of the left average versus the right average frontal sinus lobe cross-sectional areas in the population, neither for males nor for females. The growth rate is shown to be nonuniform and differs between males and females. We demonstrate the use of a sigmoid function interpolation to characterize one aspect of ontogeny, namely, the functional relation between the cross-sectional area of the frontal sinus and the age of the individual. Ontogenetic trajectories of these cross-sectional areas are remarkably well modeled by a sigmoid function (logistic curve) with suitably estimated parameters for development up to an age of 11 years (females) and 9 years (males). However, these developmental curves also reliably predict the average adult cross-sectional area at age 19 (99% for females, 95% for males). Apart from possible inadequacies of the data set, we also discuss the possibility of heterochrony in the ontogenetic trajectory before versus after puberty.