Figure 2

Detailed visualization and analysis of the overall morphology of a stage 4 T. wilhelma bud (data set E, see Additional file 2) based on SR μCT x-ray absorption and volumetric measurements. (A) Stereo pair rendering with segmentation of morphological structures: sponge tissue (yellow) separated into cortex (co) and choanoderm (cd) with developed choanocyte chambers (cc), exopinacoderm (exp), skeleton (red) and aquiferous system (blue) with lacunar system cavities (lsc). (B) Related volumetric measurements. Proportions [%] of sponge tissue, skeleton and aquiferous system measured on 1.4 μm slices. Proportional volume is given for all three spatial directions (x, y and z axes) and as xyz averages with standard deviations in relation to the sponge centre (x, y, z = 0,0,0 μm); arrows and lower case letters refer to C - N (slice images). Main body structures and body extensions (ext) are marked in grayscale. (C - N) examples of 1.4 μm slices in grayscale (left column) and colored x-ray absorption-based segmentation of morphological elements (right column). Two slices are presented per dataset direction: xy slices (C, D, I & J), zx slices (E, F, K & L), zy slices (G, H, M & N); lower case letters and lines in grayscale slice images mark the corresponding positions of the orthogonal planes shown as examples in C - N.