A double-label study of efferent projections from the Edinger-Westphal nucleus in goldfish and kelp bass

Abstract

The Edinger-Westphal nucleus in goldfish was identified by retrograde labeling from the ciliary ganglion. In the same animals a few neurons near this nucleus (perinuclear Edinger-Westphal neurons) were labeled by a different retrograde tracer injected into the cerebellum. No double-labeled cells were found. Similar results were obtained in kelp bass, except that in this species no cerebellar-projecting perinuclear neurons were observed. Cerebellar-projecting Edinger-Westphal neurons have previously been described in some mammals, but not in other vertebrates. Therefore the homology of cerebellar-projecting cells of the Edinger-Westphal region in mammals and teleost fishes is doubtful.The Edinger-Westphal nucleus (EW) of primates is a midbrain cell group that controls ocular accommodation and the pupillary reflex via a synapse in the ciliary ganglion [l, 2, 5, 16]. Although putative homologues of EW have been proposed for many other vertebrate groups, the midbrain neurons presynaptic to the ciliary ganglion have been identified by modern experimental techniques in only a few non-primate species (for review see ref. 21). In some of these species the connections of EW were shown to be more complex than previously assumed. For example, in cats [ll, 20] and rabbits [7], most of the preganglionic neurons lie outside of EW (as classically defined by descriptive anatomy). Furthermore, recent experiments have shown that many EW cells project to the spinal cord, cerebellum and other lower brainstem structures in several primates [24,16], and non-primate mammals [8][9][10][11][12]. The functions of these efferent pathways, and their relationship (if any) to the preganglionic pathway, are not fully understood.

Afferent and efferent connections of the cerebellum of a salmonid, the rainbow trout (Oncorhynchus mykiss): A tract‐tracing study

“…The partial discrepancy with Wullimann and Northcutt's results is probably due to the fact that the trout nucleus isthmi were defined as the tectum‐related nucleus (Pérez et al,2000), which does not include the adjacent precerebellar cells and neuropil. On the other hand, precerebellar cells were observed in the Edinger‐Westphal nucleus of the goldfish and the sunfish (Wathey and Wullimann,1988; Wullimann and Northcutt,1988), although not in the kelp bass (Wathey and Wullimann,1988) or the trout (present results).…”

Co-localization of nitric oxide synthase and choline acetyltransferase in the brain of the goldfish (Carassius auratus)

“…The presence of ChAT-positive cells has not previously been reported for other fishes (Molist et al, 1993;Adrio et al, 2000;Anadó n et al, 2000;Pé rez et al, 2000;Clemente et al, 2004); however, it has been reported for other vertebrates (Tago et al, 1989;Medina et al, 1993;Marín et al, 1997). Like in land vertebrates, the Edinger-Westphal nucleus projects to the cilliary ganglion in goldfish (Wathey and Wullimann, 1988). In pigeon has been reported that NO participates in eye related parasympathetic reflexes (Zagvazdin et al, 1996), but the source(s) of this NO and the point at which it is critical remain to be determined (Cuthbertson et al, 1999;Zagvazdin et al, 2000).…”

Distribution of thyrotropin‐releasing hormone (TRH) immunoreactivity in the brain of the zebrafish (Danio rerio)

“…In zebrafish, the Edinger‐Westphal nucleus of Wullimann et al (1996) contains large TRHir cells. These are considered to be preganglionic cells innervating the ciliary ganglion (Wathey, 1988; Wathey and Wullimann, 1988). TRH immunoreactivity has been noted in a few vagal motoneurons (see below), which in view of their position within the nucleus may be preganglionic cells.…”