Getting Nosy: Olfactory Rosette Morphology and Lamellar Microstructure of Two Chondrichthyan Species.

This article focuses on the olfactory morphology and sensory surface distribution in two chondrichthyan species: the Pacific spiny dogfish (Squalus suckleyi) and the spotted ratfish (Hydrolagus colliei). Using contrast-enhanced microCT and scanning electron microscopy (SEM), the study describes the gross anatomy and lamellar microstructure of their olfactory rosettes, revealing that lamellae in the center of the rosette are larger with more secondary folds, but the percentage of sensory epithelium remains consistent across lamellar positions. A novel method combining 3D microCT data with 2D SEM data was developed to better estimate lamellar sensory surface area, accounting for complex folding. The findings suggest that unlike previous observations in hammerhead sharks, sensory tissue distribution in these species does not vary with lamellar position, highlighting the need for further research into internal fluid dynamics of olfactory chambers to understand the relationship between water flow and sensory morphology in chondrichthyans.