Mitral cell dendrites: a comparative approach

Abstract

Phylogenetically persistent structures such as the mitral cells of the vertebrate olfactory bulb undergo changes in their dendritic arbor in the course of evolution. The morphology of mitral cells and the main elements of the olfactory bulb circuit in all classes of vertebrates are reviewed in this paper. Most of the neuronal elements found in the mammalian olfactory bulb are present in anamniotes. However, in contrast to those of amniotes, the mitral cells of most anamniotes lack basal dendrites, and periglomerular cells are absent in fish. This suggests a different circuitry and therefore drastic changes in the processing of olfactory information within the olfactory bulb. Lateral inhibition, conferred by basal dendrites in anamniotes, must then utilize other mechanisms in anamniotes. Moreover, the marked segregation of olfactory inputs onto mammalian mitral cells is less obvious in mitral cells of anamniotes that lack basal dendrites. The general role of dendrites, including those of mitral cells, is discussed in the light of increasing evidence for dendritic excitability. The evolutionary significance of mitral cell basal dendrites is also discussed.

Dendritic growth gated by a steroid hormone receptor underlies increases in activity in the developing Drosophila locomotor system

“…The growth of these arbors occurs by addition of new dendritic segments that "fill in" existing territory, as well as at the perimeter of the tree, thus widening its reach. Such scaling growth of dendritic arbors in relation to body size is a widespread phenomenon and has previously been observed in different types of nerve cells, including Purkinje, pyramidal, olfactory mitral cells and sympathetic ganglionic neurons (3,4,52,53).…”

Odor Encoding as an Active, Dynamical Process: Experiments, Computation, and Theory

“…rabbit and turtle [Mori et al 1981[Mori et al , 1983) and thus combine inputs with different chemical sources. Such patterns are common in lower vertebrates (Dryer & Graziadei 1994, Nieuwenhuys 1967 and in the AL of many insects (e.g. locusts and wasps) (Laurent 1996, Masson & Mustaparta 1990 (Dryer & Graziadei 1994).…”

“…Such patterns are common in lower vertebrates (Dryer & Graziadei 1994, Nieuwenhuys 1967 and in the AL of many insects (e.g. locusts and wasps) (Laurent 1996, Masson & Mustaparta 1990 (Dryer & Graziadei 1994). GC-mediated pathways may indeed link M/TCs whose somata and input glomeruli lie millimeters apart (Shipley & Ennis 1996).…”

“…Finally, output neurons may send axonal collaterals within the OB/AL, thus influencing other neurons directly or polysynaptically (Nicoll 1971b, Nicoll & Jahr 1982, Gray & Skinner 1988. In short, ORNs affect neurons other than their immediate targets in glomeruli, even if the underlying lateral circuits vary across species (Dryer & Graziadei 1994). The OB (like the AL) is not a simple point-to-point relay (Kauer 1991).…”

From the Olfactory Bulb to Higher Brain Centers: Genetic Visualization of Secondary Olfactory Pathways in Zebrafish

“…Odor information transfer from the olfactory bulb to higher brain centers It has been long believed that MCs in teleost fishes typically have multiple primary dendrites innervating multiple glomeruli ( Dryer and Graziadei, 1994). However, a recent study (Fuller et al, 2006) reported a revised description of zebrafish MC morphology in which the majority of retrogradely labeled MCs have a single primary dendrite with a discrete tuft and a smaller proportion of MCs showing the multidendritic morphology also innervates a single glomerulus.…”