Innervation Patterns of Harp Seal (Pagophilus Groenlandicus) Vibrissal Sensory Systems

The study on harp seal vibrissal sensory systems revealed that harp seals had 88-105 Follicle-Sinus Complexes (F-SCs) with a tripartite blood organization system. Medial F-SCs had more symmetrical dermal capsule thickness and nerve distribution, while lateral F-SCs had higher axon counts, averaging 1221 axons per F-SC. The study found that conventional methods overestimated total innervation by about 10-20%. The relationship between axon count and F-SC surface area was non-linear, and axon densities were consistent across the snout. The findings supported the idea of functional compartmentalization between medial microvibrissae and lateral macrovibrissae, suggesting that vibrissal innervation variation among mammals diverged due to phylogeny and environmental factors.