Chemosensation is the biological process by which organisms detect chemical stimuli forming the basis for taste and smell perception. While vertebrate chemosensory systems traditionally center around olfactory and gustatory pathways, recent research has uncovered an auxiliary mechanism involving solitary chemosensory cells (SCCs). These specialized cells are dispersed throughout the various epithelial tissues, particularly near the taste buds and the olfactory epithelium, as well as extending into the respiratory and gastrointestinal tracts.
SCCs exhibit remarkable structural and functional diversity across taxa. In the aquatic vertebrates, chemosensory cells are found both internally and externally, enabling detection of various waterborne molecules. Originally identified in fish, SCCs have since been observed in a wide range of species including rodents, amphibians, reptiles, bovines and humans. In mammals, they play a pivotal role in sensing irritants and triggering protective reflexes such as coughing and sneezing while also contributing to immune responses and appetite regulation.
This review synthesizes current insights into the morphology, distribution and physiological roles of SCCs, highlighting their significance in chemosensory perception and their broader impact on homeostasis and adaptive behavior.
