The Innervation of the Mystacial Pad in the Adult Rat Studied by Anterograde Transport of HRP Conjugates

The study investigated the innervation of the mystacial pad in adult rats using anterograde transport of HRP conjugates. Tracers were injected into the trigeminal ganglion, and survival times ranged from 6 to 24 hours. The research revealed that the innervation, particularly by fine-caliber axons, was more extensive and complex than previously described. Different tracers, WGA-HRP and B-HRP, produced distinct labeling patterns depending on survival time, affecting both peripheral and central terminations. WGA-HRP densely labeled all afferents and peripheral endings, while B-HRP preferentially labeled larger afferents initially, with smaller profiles labeled over time. The study highlighted the complexity of the mystacial pad's innervation and the importance of considering survival time when interpreting tracer results.