Quick Facts
Mitral cells are neurons with pyramidal bodies located in the olfactory bulb, being the second stage in the pathway to the cortex; they receive impulses in the olfactory glomeruli from the olfactory cells and transmit impulses through the olfactory tracts to various areas of the cortex (Dorland, 2011).
Related parts of the anatomy
Structure and/or Key Features
The mitral cell is the principal neuron of the olfactory bulb, with a cell body diameter of 20–30 μm. Fibers of the olfactory nerve carrying sensory information synapse with the mitral cells. The axons of mitral cells coalesce to form the major output of the olfactory bulb to the cerebral cortex (Blass, 1988; Barlow and Mollon, 1982).
The cell body of mitral cells is made up of a large circular nucleus and a cytoplasm. Within the nucleus, there are one or multiple apparent nucleoli as well as granular chromatin that are spread out around the nucleus. A large number of ribosomes, as well as prominent Golgi bodies are situated in the perikaryon of mitral cells. Dendrites and axons arise from the cell body. The point at which the axon arises from the cell body is referred to as the axon hillock. The cell bodies of mitral cells are arranged in a way that they form a mitral cell layer that is internal to the glomerular and external plexiform layers (Blass, 1988; Farbman et al., 1992).
The dendrites of mitral cells arise from the apical aspect of the cell body. The dendrite travels superficially, and into a glomerulus (in the glomerular layer) via the external plexiform layer where it branches abundantly, forming a dendritic tree of thin dendritic processes (Farbman et al., 1992).
The mitral cells have an additional group of dendrites called the basal dendrites, which are not involved with the glomeruli. These basal dendrites synapse with the dendrites of the granular cells. These synapses are referred to as dendrodendritic synapses (Brown, 2012).
The axons of the mitral cell travel caudally and eventually coalesce to form the lateral olfactory tract, which is the major output of the olfactory bulb to the cerebral cortex. The axons of mitral cells have collaterals that branch off them and terminate on the anterior olfactory nucleus. The cells of the anterior olfactory nucleus in turn project back to the dendritic spines of the granular cells which lie in close proximity to the dendrodendritic synapses with mitral cells (Brown, 2012; Barlow and Mollon, 1982).
Anatomical Relations
The cell bodies of the mitral cells are situated in the mitral layer of the olfactory bulb. Their dendrites extend across the external plexiform and glomerular layers of the olfactory bulb.
Function
Mitral cells are vital in the olfactory transduction. Their axons form the major output of the olfactory bulb to the cerebral cortex (Barlow and Mollon, 1982).
Neural impulses from the mitral cell travel to the cerebral cortex where it activates target neurons by releasing glutamate. The neural impulse also activates the granular cells through collaterals from axons, as well as by projecting back to the basal dendrites that lie in close proximity to the dendrodendritic synapses between the granular and mitral cells (Brown, 2012).
Clinical Correlates
—Anosmia
References
Barlow, H. B. and Mollon, J. D. (1982) Senses. Cambridge Studies in Philosophy: Cambridge University Press.
Blass, E. M. (1988) Developmental psychobiology and behavioral ecology. Handbook of behavioral neurobiology: Plenum Press.
Brown, A. G. (2012) Nerve Cells and Nervous Systems: An Introduction to Neuroscience. Springer London.
Dorland, W. (2011) Dorland's Illustrated Medical Dictionary. 32nd edn. Philadelphia, USA: Elsevier Saunders.
Farbman, A. I., Bard, J. B. L., Barlow, P. W. and Kirk, D. L. (1992) Cell Biology of Olfaction. Developmental and Cell Biology Series: Cambridge University Press.
