part of start stage end stage postoptic commissure tract of the postoptic commissure Tract that extends from the postoptic commissure through a curved trajectory in the diencephalon into the ventral midbrain. In the anterior diencephalon the TOP is a single tract but caudally the axons of the TPOC diverge and tend to grow in distinct parallel bundles. The more dorsal bundles extend in the dorsolateral tegmentum, the ventral bundles of the TPOC merge into the DLF in the hindbrain. ZFA:0001366 TPOC TAO:0001366 zebrafish_anatomy white matter pharyngula:prim-5 adult