Distribution and light microscopic features of granule cells in the cochlear nuclei of cat, rat, and mouse

Abstract

In the present study the cytology and the topography of the cochlear granule cell domain (a comprehensive term introduced here for all granule cell-containing regions of the cochlear nuclear complex) have been studied light microscopically in Nissl, Bielschowsky, and Golgi-Del Rio-Hortega material of cats, rats, and mice; in Golig rapid material of 0-14-day-old kittens; and in sections of 6-week-old kittens following HRP injections in the superficial dorsal cochlear nucleus (DCN). The domain has been parcellated in seven subdivisions which, in spite of some species' differences, are easily identifiable in all of the included animals. The cochlear granule cells are considered as a particular class of neuron, which is slightly different from, but nevertheless principally similar to the cerebellar granule cells in both shape and mode of neuronal connections. The digitiform terminals of the cochlear granule cells differentiate after the first two weeks of extrauterine life. In several respects these cells show larger variation among species than do the cerebellar granules, the similarity between the two classes of granule cells being most conspicuous in the rodent. The silver, Golgi rapid, and HRP material suggest that all, or at least the majority, of the granule cell axons project to the molecular layer of the DCN, forming parallel fibers similar to those of the cerebellar cortex. Also, the cochlear parallel fibers traverse the spiny apical dendrites of principal neurons (the pyramidal cells) and the smoother dendrites of molecular layer stellate cells.

Granule Cell Activation of Complex-Spiking Neurons in Dorsal Cochlear Nucleus

“…C, E xamples of discharge rate versus sound level curves in response to BF tones (solid lines) and broadband noise (dashed lines) for the four common response types observed. Sound levels in all plots are shown in dB of attenuation; (Mugnaini et al, 1980). PFs make excitatory terminals on pyramidal cells (and perhaps giant cells; not shown) and on inhibitory interneurons, including Golgi, stellate (not shown), and cartwheel cells.…”

“…A schematic of the circuitry in superficial DC N is shown in Figure 1. Granule cell axons make direct excitatory terminals on the apical dendrites of pyramidal cells, which are one type of DC N principal cell, but they also activate inhibitory interneurons in the superficial layer (Mugnaini et al, 1980;Manis, 1989;Osen et al, 1995;Manis and Molitor, 1996). Most numerous among these interneurons are cartwheel cells (Wouterlood and Mugnaini, 1984), which bear a homology to cerebellar Purkinje cells (Berrebi et al, 1990).…”

Olivocochlear Neuron Central Anatomy Is Normal in α9 Knockout Mice

“…This staining did not extend as far rostrally as the medial edge staining. Some staining was present in the subpenduncular corner, a small region of granule cells just ventral to the inferior cerebellar peduncle (Mugnaini et al 1980), and a very small amount of staining extended dorsally along the medial border of the dorsal cochlear nucleus. Staining was also present within the core of the ventral cochlear nucleus, especially in the caudal auditory nerve root where it occurred within islands of cells between the incoming fascicles of auditory nerve fibers.…”

Activation of muscarinic receptors increases the activity of the granule neurones of the rat dorsal cochlear nucleus—a calcium imaging study

“…In the rat, the somatic diameter of cochlear granule cells is 6-8 µm [1,22,23,30], thus they are the smallest neurones in this nucleus. Because the selection protocol applied in the present work relied on choosing ROIs whose size was the same as the somatic dimensions of the granule cells, it was ensured that only this cell type was considered for data analysis -especially as the Golgi cells (whose size is the closest to that of the granule neurones [22]) hyperpolarize when subjected to cholinergic stimulation [17].…”

“…Granule cells are the smallest and most numerous neurones of the DCN, with a somatic diameter of 6-8 µm [1,22,23]. Their axons travel towards the outer layers of the DCN, and eventually form the parallel fibre network which provides a major excitatory, glutamatergic input for the apical dendritic trees of the pyramidal cells, and for the superficially situated dendrites of the giant neurones ( [20,31,40]; for a review see [25]).…”