Figure 4.

3D volume renderings of stage 1 to 4 buds of T. wilhelma and corresponding virtual sections from SR-μCT data elucidating the development of distinct morphological structures. (A) stage 1 bud without choanoderm/cortex differentiation (msb - megasclere bundle); (B) stage 2 bud without a separated choanoderm (dcd - developing choanoderm, dco - developing cortex) but displaying the first differentiated aquiferous system canals; (C) stage 3 bud with an early developing choanoderm (dcd) and developing cortex (dco), (D - E) stage 4 buds with differentiated choanoderm (cd) and cortex (co) regions, the latter displaying lacunar cavities.