Morphological defects caused by injection of rbm7 MO (A). Mild phenotype fish show slight developmental delay, and shorter body length. Rostrally the head is smaller than control fish while caudally the head looks slightly swollen. Body shape in the moderate phenotype looks compromised and head oedema increased, sporadically we could observe heart oedema as well. Body shape of the severe fish is completely disrupted, swelling of the head is more severe, and we detected smaller forehead and eyes compared with control fish (Scale bar = 200 μm). On the bottom left: RT-PCR of zebrafish cDNA shows efficacy of morpholino against In1-Ex2 boundary. Position of morpholinos is explained in the graph on the right. Below: graphs showing mortality and phenotype rates at 24 hpf. (B) Hindbrain defects in morphant fish. Cranial motor neurons nuclei are well defined in 5 nuclei in wild type fish: Oculomotor neurons (III), Trochlear neurons (IV), Trigeminal neurons (V), Facial neurons (VII), Vagal neurons (X). rbm7-MO seems to have a milder effect on cranial motor-neurons development and to affect predominantly vagal nucleus (nX) which result shorter than controls. Hindbrain structures in exosc8-MO are more generally affected the moderate phenotype fish. Only nX is partially preserved. Exosc3-MO affects predominantly nVII (facial neurons) (Scale bar = 200 μm).