Neurobiological indicators of olfactory sensitivity in a cartilaginous and a bony fish

This research provides new insights into the neuroanatomical organisation of the ascending olfactory pathway of elasmobranchs, using a comparative and multi-modal approach. Taken together, the results suggest that the relative volume of the olfactory bulbs remains a reliable proxy for olfactory capabilities, while the convergence ratio of olfactory inputs to the brain indicates the sensitivity of this sensory modality at the system level. Five morphological types of olfactory receptor neurons are described, and the differential distribution of three microvilli-bearing types across the olfactory rosette may reflect an adaptation for sampling certain chemicals more efficiently.