Mitral/tufted cell

Jia C.P. and Halpem M. (1997). Segregated populations of mitral/tufted cells in the accessory olfactory bulb. Neuroreport 8, 1887-1890. 

Salazar I, Brennan PA (2001) Retrograde labelling of mitral/tufted cells in the mouse accessory olfactory bulb following local injections of the lipophilic tracer Dil into the vomeronasal amygdala. Brain Res 896 198-203... 

Katoh K, Koshimoto H, Tani A, Mori K (1993) Coding of odor molecules by mitral/tufted cells in rabbit olfactory bulb. II. Aromatic compounds. J Neurophysiol 70 2161-2175 Kawakami K (2004) Transgenesis and gene trap methods in zebrafish by using the Tol2 transpos-able element. Methods Cell Biol 77 201-222... 

Mitral Cell Layer, Mitral/Tufted Cell Synapses, and Neurochemistry. 158... 

The basic circuitry of the MOB. Axons of ORNs travel in the ONL and synapse in the GL on the dendrites of mitrai ceiis (MC), tufted ceiis (externai tufted ceii, ET middie tufted ceii, MT), and generic juxtagiomeruiar (JG) neurons, which include perigiomeruiar ceiis (PG), ET ceiis, and short axon ceiis (SA). SA ceiis interconnect different giomeruii. There are serial and reciprocal synapses between the apicai dendrites of mitral/tufted cells and the processes of JG neurons. Superficial tufted cells (ST) are located in the superficial EPL or at the GL-EPL border. The lateral dendrites of mitral/tufted cells form serial and reciprocal synapses with the apical dendrites of granule cells (GC) in the EPL. GCs are located in the GCL and the MCL. The axons of mitral/tufted cells project locally to GCs (not shown) and also to primary olfactory cortex via the lateral olfactory tract (LOT). The bulb also contains other populations of interneurons neurons, including the van Gehuchten cells (VG) within the EPL... 

The EPL lies beneath or deep to the glomeruli, and it primarily consists of dense neuropil formed by the dendrites of mitral cells and GCs that ascend from the MCL and GCL, respectively. Relative to other MOB layers, the EPL has a low cell density. In Nissl-stained sections, however, it can nevertheless be seen to contain significant numbers of neurons ( Figure 6-3). These include several subtypes of tufted cells and intrinsic interneurons, which are described later. Because tufted cells are in many aspects similar to mitral cells, and as mitral and tufted cell dendrites cannot be distinguished ultrastructurally, the term mitral/tufted cell is often used when generalizing to these two cell populations. The dominant feature of the EPL is nevertheless the extensive dendrodendritic synapses between mitral/tufted cells and GCs. 

ON Input As noted earlier, mitral/tufted cell apical dendrites respond to glutamate released from the ON via AMPA and NMDA receptors (Ennis et al., 1996, 2001 Aroniadou-Anderjaska et al., 1997 Chen and Shepherd 1997). The NMDA receptor-mediated response component is of unusually long duration, leading to a late spiking component in response to ON input (Ennis et al., 1996, 2001 Aroniadou-Anderjaska et al., 1997). An mGluR-mediated component of ON-evoked currents in mitral cells also occurs but is typically small under normal conditions (De Saint Jan and Westbrook, 2005 Ennis et al., 2006), yet, as will be discussed later, blockade of these receptors significantly alters ON-evoked spiking. 

The GCL is the deepest neuronal layer in the bulb, and it contains the largest number of cells. Most of the neurons of the GCL are the GCs, but there are also small numbers of Golgi cells, Cajal cells, and Blanes cells. As discussed earlier, the GCs are inhibitory GABAergic cells that form dendrodendritic synapses with mitral/tufted cells in the EPL. 

Major connections of the main olfactory system. Axons of MOB mitral/tufted cells (circles in the EPL and MCL, respectively) project as the LOT to synapse in a number of structures collectively referred to as primary olfactory cortex (POC). Centrifugal inputs to MOB include feedback projections from POC as well as inputs from subcortical forebrain and brainstem neuromodulatory cell groups. Abbreviations AON, anterior olfactory nucleus DP, dorsal peduncular cortex Ent, entorhinal cortex IG-AHC, indusium griseum-anterior hippocampal continuation LC, locus coeruleus NDB, nucleus of the diagonal band PeCo, periamygdaloid cortex PC, piriform cortex RN, raphe nuclei (dorsal and median raphe) TT, taenia tecta Tu, olfactory tubercle... 

---