E MOS. By contrast, our mechanistic understanding of AOS function continues to be fragmentary (Box 1). In this review post, we supply an update on current information of your rodent AOS and discuss some of the significant challenges lying ahead. The primary emphasis of this critique issues the nature in the computations performed by the initial stages in the AOS, namely sensory neurons of the VNO and circuits in the accessory olfactory bulb (AOB).The vomeronasal organThe rodent VNO can be a paired cylindrical structure in the base on the anterior nasal septum (Meredith 1991; Halpern and MartinezMarcos 2003). Just above the palate, the blind-ended tubular organ, enclosed in a cartilaginous capsule, opens anteriorly to the nasal cavity via the vomeronasal duct (Figure 1). Whether the organ is functional at birth or gains functionality during a later developmental stage continues to be topic to debate (Box 2). Within the adult mouse, every single VNO harbors about 100 000 to 200 000 vomeronasal sensory neurons (VSNs; Wilson and Raisman 1980), which gain both structural and metabolic help from a band of sustentacular cells within the most superficial layer of a crescent-shaped pseudostratified neuroepithelium. VSNs show a characteristic morphology: as bipolar neurons, they extend a single unbranched dendrite in the 121521-90-2 custom synthesis apical pole of a modest elliptical soma ( 5 in diameter). The apical dendrites terminate within a paddle-shaped swelling that harbors many microvilli at its tip (knob). These microvilli are immersed in a viscous mucus that may be secreted by lateral glands and fills the entire VNO lumen. Therefore, the microvillar arrangement provides a massive extension of your neuroepithelium’s interface together with the external environment. From their basal pole, VSNs project a lengthy unmyelinated axon. In the basal lamina, hundreds of these VSN axons fasciculate into vomeronasal nerve bundles that run in dorsal path below the septal respiratory and olfactory epithelia. Collectively with olfactory nerve fibers, VSN axon bundles enter the brain through tiny fenestrations in the ethmoid bone’s cribriform plate. The vomeronasal nerve then projects along the medial olfactory bulbs and targets the glomerular layer of the AOB (Meredith 1991; Belluscio et al. 1999; Rodriguez et al. 1999). On its lateral side, the VNO is composed of hugely vascularized cavernous tissue. A prominent big blood vessel offers a characteristic anatomical landmark (Figure 1). In his original publication, Jacobson currently noted the rich innervation on the organ’s lateral elements (Jacobson et al. 1998). The majority of these sympathetic fibers originate in the superior cervical ganglion, enter the posterior VNO along the nasopalatine nerve, and innervate the large lateral vessel (Meredith and O’Connell, 1979; Eccles, 1982; Ben-Shaul et al., 2010). Although in many species vomeronasal stimulus uptake isChemical Senses, 2018, Vol. 43, No.Box 1 The AOS: an emerging multi-scale model to study how sensory stimuli drive behavior A crucial target in neuroscience would be to have an understanding of how sensory stimuli are detected and processed to in the end drive behavior. Provided the inherent complexity in the activity, attempts to get a holistic (i.e., multi-scale) analytical perspective on sensory coding have regularly resorted to reductionist approaches in invertebrate model organisms including nematodes or fruit flies. In such models, the “from-gene-tobehavior” technique has confirmed very effective and, accordingly, has led to numerous breakth.