Central Projections of Primary Sensory Afferents to the Spinal Dorsal Horn in the Long-Tailed Stingray, Himantura fai

Abstract

The central projections of primary sensory afferents innervating the caudal region of the pectoral fin of the long-tailed stingray (Himantura fai) were labeled by applying the lipophilic carbocyanine dye DiI to the dorsal roots in fixed tissue. These observations were complemented by examination of hemotoxylin and eosin-stained paraffin sections of the dorsal root entry zone, and transmission electron microscopy of the dorsal horn. Transverse sections of the sensory nerve and dorsal root revealed two distinct myelinated axon sizes in the sensory nerve. Although the thick and thin axons do not appear to group together in the sensory nerves and dorsal root, they segregate into a dorsally direc..