The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)


Size and Shape Maturation of the Human Cochlea

THANAKUL WANNAPRASERT1, FRED SPOOR2 and NATHAN JEFFERY1.

1Institute of Ageing & Chronic Disease, University of Liverpool, United Kingdom, 2Dept. Human Evolution, Max Planck Institute for Evolutionary Anthropology, Germany

Thursday 11:00-11:15, Ballroom B Add to calendar

Previous studies suggest that the human cochlea attains a size within the adult range as early as 23 weeks in utero, but 3D shape changes have as yet not been assessed. Here we document the shape component of form change of the human fetal cochlea and test whether the shape is distinct from that seen among adults. We collected microCT data for 12 fetuses ranging from 16 to 39weeks in utero and data for 5 adults. Each cochlea was reconstructed in 3D and a spline function was fitted along the centre of the duct. A total of 25 landmarks were placed at equidistant points along the line and were subjected to form analysis. Measurements of cochlear length, width, height and volume were also collected. Findings indicate that there is little difference of cochlea shape between fetuses and adults but, in contrast to previous studies, a small difference of size was observed.

Analyses revealed a significant correlation (p<0.05) of PC1 scores with centroid size. This was associated with shape changes primarily in the apical region. Discriminant function analysis found no significant differences of cochlear shape in pairwise comparisons between the smallest fetuses, largest fetuses and adults. Mann-Witney Tests suggest that the adult cochlea is on average significantly bigger than the largest fetuses in terms of length (+10%), width (+10%) and volume (+30%). These results suggest that whilst the general coiled shape is reached at an early stage of development, there may be size related morphological changes after birth.

TW was funded by a scholarship from the Royal Thai Embassy, London.

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