Morphology and immunohistochemistry of efferent neurons of the goldfish corpus cerebelli

Abstract

In teleosts, cerebellar efferent neurons, known as eurydendroid cells, are dispersed within the cerebellar cortex rather than coalescing into deep cerebellar nuclei. To clarify their morphology, eurydendroid cells were labeled retrogradely by biotinylated dextran amine injection into the base of the corpus cerebelli. Labeling allowed the cells to be classified into three types-fusiform, polygonal, and monopolar-depending on their somal shapes and numbers of primary dendrites. The fusiform and polygonal type cells were distributed not only in the Purkinje cell layer but also in the molecular and granule cell layers. The monopolar type cells were distributed predominantly in the Purkinje cell layer of the ventrocaudal portion of the corpus cerebelli. These results suggest that there are some functional differences between these eurydendroid cell types. The eurydendroid cells were double-labeled by retrograde labeling and immunohistochemistry using specific antibodies against GABA, aspartate, and zebrin II. No GABA-like immunoreactivity was detected in the retrogradely labeled eurydendroid cells. About half of retrogradely labeled cells were immunoreactive to the anti-aspartate antibody, suggesting that some eurydendroid cells utilize aspartate as a neurotransmitter. Zebrin II reacts with cerebellar Purkinje cells but left all retrogradely labeled neurons nonreactive, although some of these were surrounded by immunopositive fibers. This relationship between the eurydendroid and Purkinje cells is similar to that between the deep cerebellar nuclei and Purkinje cells in mammals.

Fiber Connections of the Caudal Corpus Cerebelli, with Special Reference to the Intrinsic Circuitry, in a Teleost (<b><i>Oreochromis niloticus</i></b>)

“…10), in agreement with former studies of the goldfish CC [Brochu et al, 1990;Ikenaga et al, 2005]. After large-dose injections of FG into the dcC, we observed many labeled cell bodies in the GGL of the vcC (Fig.…”

“…To better understand the organization of the cerebellar circuitry involved in the processing of descending telencephalic information from the input stage to the output stage, we injected tracers into the ML of the dcC and the vcC in Nile tilapia. We further confirmed PuC projections from the vcC to the dcC via double immunofluorescence labeling for zebrin II [aldolase C; Ahn et al, 1994], which is a specific marker for PuC in teleosts as well as mammals [Brochu et al, 1990;Sillitoe et al, 2004;Sugihara and Shinoda, 2004;Ikenaga et al, 2005].…”

Cell morphology and circuitry in the central lobes of the mormyrid cerebellum

“…Several features of the local cerebellar circuitry that are described here for the mormyrid central lobes are also present in the cerebellums of other teleosts (Finger, 1983;Ikenaga et al, 2005;Meek, 1998;Murakami and Morita, 1987;Pouwels, 1978). Thus, in other teleosts as in mormyrids: a) climbing fibers terminate within the largecelled ganglionic layer of the cortex and do not enter the molecular layer; b) the dendrites of both Purkinje cells and efferent cells are fan-like and oriented in parasagittal planes perpendicular to the parallel fibers; and c) most Purkinje cell axons do not leave the cortex but terminate locally on efferent cells, other Purkinje cells, and deep stellate cells.…”

“…nopterygii; Finger, 1983;Ikenaga et al 2005;Lannoo et al 1991;Meek, 1998). Besides these anatomical features, the mormyrid cerebellum is also of interest because of its involvement in the active electrosensory system of these fish, a system with several advantages for studying cerebellar function.…”

How Neuronal Migration Contributes to the Morphogenesis of the CNS: Insights from the Zebrafish

“…Only a few of them express the Purkinje cell marker zebrin II [Lannoo et al, 1991] and GABA-synthesizing enzymes gad65/67a,b, whereas many express calretinin [Castro et al, 2006b]. These features suggest that dlx5a-6a:GFP+ cells in the zebrafish cerebellum are eurydendroid neurons, the equivalent in the fish of the neurons of the DCN that project outside of the cerebellum [Ikenaga et al, 2005;Nieuwenhuys, 1988]. Indeed, recent studies in the mouse have shown that glutamatergic neurons of the DCN are generated in the upper RL [Wang et al, 2005], rather than in the cerebellar ventricular zone as hypothesized by classical lineage studies.…”