Observations of human fetal otoconial membranes.

Intact otoconial membranes from 31 human fetuses ranging in gestational age from 14 to 36 weeks were studied. At all stages of development specimens from different individuals showed marked variations in overall shape. During the course of the second and third trimesters, both saccular and utricular otoconial membranes were found to increase three to fourfold in surface area and more than twofold in weight. Near the end of gestation the fetal specimens were about equal in area and weight to otoconial membranes from children up to 13 years of age. However, the crystal layers of the fetal membranes has less prominently developed surface contours than usually observed in children and adults, indicating that maturational changes continue after the time of birth.