Descriptive growth model of the height of stapes in the fetus: a histopathological study of the temporal bone.

Temporal bone histological findings can be evaluated from several points of view. The most basic consists of a description of the characteristics and abnormalities of particular temporal bones. The second one is the measurement of various structures in a larger set of temporal bones and the monitoring of these structures over time. The height of stapes was measured in a set of 40 temporal bones from 27 fetuses, and the growth of stapes from the 13th to 36th weeks of pregnancy was determined. A computer-assisted nonlinear regression analysis of diagnostics enabling simultaneous examination of data (influential points, i.e., outliers and leverages) was carried out, a growth curve model proposed and a mathematical method with Ratkowski criteria for estimation applied to find the best descriptive model of the height of stapes versus time y= f(x) growth curve; the results of 13 growth models were examined. It was found that the maximum growth of the height of stapes was between the 13th and the 24th weeks of pregnancy. The average height of stapes was 1.05 mm in the 13th week and 2.6 mm in the 24th week. Later, after the 25th week, the growth of the height of stapes was slower, and the average height in the 30th week was 3.0 mm.