Retrograde tracing methods are employed here to demonstrate that neurons in
the trigeminal mesencephalic nucleus (5me) project to the superior collicu
lus (SC) in the rat. These neurons, mainly of small size, are situated bila
terally in the caudal part of the nucleus. Anterograde tracing studies demo
nstrated the existence of SC projections to neurons in 5me. The SC fibers c
ontact 'en passant' small as well as large cell bodies of 5me neurons. Thes
e pathways suggested a role of the 5me neurons in oculomotor control and as
sociated ore-facial functions. (C) 2000 Elsevier Science Ireland Ltd. All r
ights reserved.