Three-Dimensional Microanatomy of Longitudinal Lanceolate Endings in Rat Vibrissae

The study re-examined the fine structure and relationships of longitudinal lanceolate endings in rat vibrissae using immunohistochemistry, scanning electron microscopy, and transmission electron microscopy. It found that these sensory terminals consist of triplet units with a flattened axon terminal flanked by Schwann cell lamellae. Two distinct parts were identified: a principal portion with axon fingers protruding from Schwann cell coverings, and an apical cone with a large axon finger in a Schwann sheath. The principal portions were linked to connective tissue, suggesting continuous deformation by hair deflections, while the apical cones were suspended in an amorphous matrix, potentially acting as transducer sites for receptor potentials during vibrissal movements.