part of develops from start stage end stage midbrain torus semicircularis TAO:0000599 zebrafish_anatomy semicircular torus Multi-tissue structure that is part of the midbrain and develops from the alar plate. The torus semicircularis is located dorsal to the lateral tegmentum where it extends into the medial tectal ventricle and receives ascending sensory octavolateralis input. ZFA:0000599 alar plate midbrain region multi-tissue structure unknown adult