Expression of zebrafish thoc6 in the brain. Expression of zebrafish thoc6 was assessed by whole mount in situ hybridization. Side views of whole mount thoc6 expression observed in 24, 48 and 72 hpf WT embryos. thoc6 is highly expressed in the developing optic tectum and the eyes at 24 hpf (A). This expression decreases at 48 (B) and 72 hpf (C) but a low level of expression is observed at the midbrain-hindbrain boundary.