CELL ATLAS OF THE MURINE ACCESSORY OLFACTORY BULB

In mice and most mammals, chemical communication is essential for regulating behavior and physiological states. Pheromones and other social chemosignals are detected by the vomeronasal organ (VNO) and transmitted via the vomeronasal nerves to the accessory olfactory bulb (AOB), which processes this information and relays it directly to the amygdala–hypothalamic complex. Despite its central role in pheromone processing, the cellular composition and functional organization of the AOB remain poorly understood. Here, we employed a multifaceted approach to comprehensively characterize AOB cellular diversity. We performed the first single-cell transcriptomic analysis of the AOB, generating a robust dataset capturing the heterogeneity of this brain region. To determine the anatomical organization of molecularly defined cell types, we applied in situ spatial profiling to map the expression of hundreds of marker genes at subcellular resolution. Integration of transcriptomic and spatial data revealed the distribution and organization of distinct AOB cell populations within tissue sections. To further characterize individual cell types, we used transgenic mouse lines expressing Cre recombinase and fluorescent reporters driven by selected marker genes. Patch-clamp recordings combined with high-resolution microscopy allowed us to assess the electrophysiological and morphological properties of specific cell populations. This integrative strategy enabled the combination of transcriptomic, spatial, electrophysiological, and morphological data, providing a multidimensional description of AOB cell types. Our study identifies two previously uncharacterized populations of excitatory neurons and represents the first comprehensive analysis of cellular diversity in the AOB, establishing a foundation for future studies of its functional organization and role in pheromone-mediated behaviors.