Human otoconial crystal growth. An approach from morphological and morphometric data.

The otoconium genesis was evaluated by morphometric procedures using transmission and scanning electron-microscopic techniques for human fetuses of 50, 110, 134, 173, 210, 220 and 232 mm crown-rump length. Different otoconial crystalline habits were found. For the elongated otoconia (hexagonal prism) different parameters were measured: (1) the mean cleavage angle value of the terminal rhombohedron was 102 (SD 0.65), which was independent of the fetal age; (2) large and short axes show a linear growing law in function of the fetal age, and (3) the otoconial volume grows following a quadratic law. A hypothesis about the physicochemical growth conditions is postulated.