Amira software v6

Sensory epithelia of the vestibular system from all available gestational stages were again manually segmented using Thermo Scientific™ Amira™ Software® v6.4.0. For all sensory epithelia, the center of mass was calculated using the Material Statistics tool. Using the X-, Y- and Z- coordinates of the region centers the distances between all neurosensory regions (3 Crista ampullaris and the macular organs of the utricle and the saccule) were measured as the vector magnitude representing the distance between two respective points (i.e., the distance between the centers of two neurosensory regions).

MicroCT scans of the fetal human temporal bone belonging to all available gestational ages were manually segmented using Thermo Scientific™ Amira™ Software® v6.4.0 and validated independently by trained anatomists. Segmented labels were cropped to reduce file size. The scala media label was isolated using the Arithmetic tool [expression (“a==bundle number of scala media”)*1]. The result obtained was resampled by the factor 2 (Resample). Subsequently, the resampled volume was processed in the Segmentation editor using five voxel dilation (Grow selection) followed by three steps of contour smoothing (Smooth labels) and a five voxel erosion (Shrink selection). Based on the smoothed scala media mask, a skeletonization was performed (Centerline tree, number of parts = 1). The resulting spatial graph was smoothed (Smooth Line Set, Smoothing = 0.85, Adhere to original data = 0.05, Number of Iterations = 200). Finally, the length of the smoothed spatial graph representing the total length of the scala media was measured (Spatial Graph Statistics).