Anatomy of the cochlear nuclear complex of guinea pig

Abstract

The cyto- and fibre-architecture of the cochlear nuclear complex of the guinea-pig has been studied in serial sections using Nissl, Golgi and combined cell-myelin staining of normal material, and a silver degeneration method after cochlear ablation. The nuclear subdivisions and major cell types can be recognised on the basis of those found in the cat, but there are some differences between the two species in the precise distribution and morphology of the neurons. The rostrodorsal part of the anteroventral cochlear nucleus (AVCN) contains predominantly spherical bushy cells, but these cannot be readily divided into large and small types as in the cat. Globular bushy cells are seen in the caudal region of the AVCN, but the majority occur in the posteroventral cochlear nucleus (PVCN), in an area extending from the nerve root right up to the boundary of the dorsal cochlear nucleus (DCN). The octopus cells constitute a distinct region in the most dorsomedial part of the PVCN underneath the DCN. Giant cells are seen scattered around the nerve root region. Multipolar and small cells are seen throughout the non-granular regions of the ventral cochlear nucleus (VCN) except for the octopus cell area, but occur mainly in the more rostral regions of the PVCN. Small cells occur in greatest abundance in the thin cap area at the dorsal edge of the VCN below a superficial granule cell layer. The latter covers the dorsolateral surface of the VCN, and a lamina of granule cells partially separates the PVCN from the DCN. The DCN can be divided into four layers. The outermost molecular layer (layer 1) is separated from the deeper regions by a prominent layer of granule cells (layer 2) which also contains the pyramidal cells. Molecular layer stellate cells are seen in layer 1 and a staggered row of cartwheel neurons is found at the boundary between layers 1 and 2. Layer 3 contains the basal dendrites of the pyramidal cells and some small (vertical) cells, and is innervated by the descending branches of the cochlear nerve. The deepest layer 4, which contains multipolar cells and giant cells, does not appear to receive this direct cochlear input.

Connections between the cochlear nuclei in guinea pig

“…However, based on cell shape, and, when possible, the number and kinds of dendrites, and, on occasion, the location of the nucleus, we are able to suggest that our three cell categories ma3 , correspond to categories described by Cant and Morest (1984) in the cat and Moore (1986), Pirsig (1986) and Hackney et al (1990) in the guinea pig. The 'elongate' group could correspond to Pirsig's (1986) fusiform cells, Moore's (1986) 'horizontal fan' cells and Hackney et al's (1990) 'lacy, elongate cells' in the dorsal cochlear nucleus, and 'bipolar, giant' cells in dorsal cochlear nucleus and ventral cochlear nucleus. The 'polygonal' cells described here are more likely to correspond to multipolar cells (Pirsig, 1986;Cant and Morest, 1984;Moo~e, 1986 andHackney et al, 1990), but also would include cells described as giant multipolar or radiate by Pirsig (1968) and Hackney et al (1990).…”

“…Osen, 1969, Moore, 1986, Cant and Morest, 1984and Hackney et al, 1990 because intracellular features and dendritic patterns were not always accessible using WGA-HRP. However, based on cell shape, and, when possible, the number and kinds of dendrites, and, on occasion, the location of the nucleus, we are able to suggest that our three cell categories ma3 , correspond to categories described by Cant and Morest (1984) in the cat and Moore (1986), Pirsig (1986) and Hackney et al (1990) in the guinea pig.…”

“…Osen, 1969, Moore, 1986, Cant and Morest, 1984and Hackney et al, 1990 because intracellular features and dendritic patterns were not always accessible using WGA-HRP. However, based on cell shape, and, when possible, the number and kinds of dendrites, and, on occasion, the location of the nucleus, we are able to suggest that our three cell categories ma3 , correspond to categories described by Cant and Morest (1984) in the cat and Moore (1986), Pirsig (1986) and Hackney et al (1990) in the guinea pig. The 'elongate' group could correspond to Pirsig's (1986) fusiform cells, Moore's (1986) 'horizontal fan' cells and Hackney et al's (1990) 'lacy, elongate cells' in the dorsal cochlear nucleus, and 'bipolar, giant' cells in dorsal cochlear nucleus and ventral cochlear nucleus.…”

Vesicular Glutamate Transporter 2 Is Associated with the Cochlear Nucleus Commissural Pathway

“…These retrogradely labeled neurons were mapped onto templates that included six transverse sections evenly extending from the caudal to rostral ends of the CN (i.e., the 14.3th, 28.6th, 42.9th, 57.2th, 71.5th, 85.8th percentiles). In cases where the BDA reaction product or FG filled both the soma and dendrites of a labeled cell, we tried to identify the cell type using the scheme of Hackney et al (1990).…”

Cells in Auditory Cortex that Project to the Cochlear Nucleus in Guinea Pigs

“…Cytoarchitectonic borders were added by comparison with adjacent, thioninstained sections. Borders within the cochlear nuclei were determined according to Hackney et al (1990). Labeled cortical cells were observed with a 40Â objective (NA = 0.85).…”