The sensory trigeminal nucleus of teleosts is the rostralmost nucleus among the trigeminal sensory nuclear group in the rhombencephalon. The sensory trigeminal nucleus is known to receive the somatosensory afferents of the ophthalmic
maxillar
and mandibular nerves. However
the central connections of the sensory trigeminal nucleus remain unclear. Efferents of the sensory trigeminal nucleus were examined by means of tract-tracing methods
in a percomorph teleost
tilapia. After tracer injections to the sensory trigeminal nucleus
labeled terminals were seen bilaterally in the ventromedial thalamic nucleus
periventricular pretectal nucleus
medial part of preglomerular nucleus
stratum album centrale of the optic tectum
ventrolateral nucleus of the semicircular torus
lateral valvular nucleus
prethalamic nucleus
tegmentoterminal nucleus
and superior and inferior reticular formation
with preference for the contralateral side. Labeled terminals were also found bilaterally in the oculomotor nucleus
trochlear nucleus
trigeminal motor nucleus
facial motor nucleus
facial lobe
descending trigeminal nucleus
medial funicular nucleus
and contralateral sensory trigeminal nucleus and inferior olive. Labeled terminals in the oculomotor nucleus and trochlear nucleus showed similar densities on both sides of the brain. However
labelings in the trigeminal motor nucleus
facial motor nucleus
facial lobe
descending trigeminal nucleus
and medial funicular nucleus showed a clear ipsilateral dominance. Reciprocal tracer injection experiments to the ventromedial thalamic nucleus
optic tectum
and semicircular torus resulted in labeled cell bodies in the sensory trigeminal nucleus
with a few also in the descending trigeminal nucleus. c 2006 Wiley-Liss
Inc.
