Solitary chemosensory cells
Encyclopedia
Solitary chemosensory cells (SCCs) (also called solitary chemoreceptor cells) are isolated elements located in epithelia of the apparatuses of endoderm
ic origin (such as respiratory and digestive apparatuses). In the aquatic vertebrates, SCCs are also present in the skin. In oral cavity, SCCs precedes the development of taste buds. For long time, SCCs were considered to be typical of aquatic vertebrates. Recently, these elements were also demonstrated in mammals.
The SCCs share common morphological and biochemical characteristics with the taste cells located in taste buds of the oro-pharyngeal cavity. In particular, they may express molecules of the chemoreceptorial cascade (such as trans-membrane taste receptors, the G-protein gustducin
, PLCbeta2, IP3R3, TRPM5
). Morphologically, the elements of SCCs are polymorphic. Some of them have an apical tuft of rigid microvilli (brush cells). Other elements have secretory exocrine granules and others may have endocrine differentiation. Often these elements are innervated. In the upper respiratory system the SCCs are contacted by the sensory endings of trigeminal nerve fibers (SubP and CGRP immunoreactive).
The SCCs of the aquatic vertebrates play a role in food search and predator avoidance. The functional role of the SCCs located in internal organs of mammals is unknown also if several hypotheses have been advanced. In nasal cavity, SCCs operate as sentinels being involved in detection of irritants and are important in the protection of the airway.
Endoderm
Endoderm is one of the three primary germ cell layers in the very early embryo. The other two layers are the ectoderm and mesoderm , with the endoderm as the intermost layer...
ic origin (such as respiratory and digestive apparatuses). In the aquatic vertebrates, SCCs are also present in the skin. In oral cavity, SCCs precedes the development of taste buds. For long time, SCCs were considered to be typical of aquatic vertebrates. Recently, these elements were also demonstrated in mammals.
The SCCs share common morphological and biochemical characteristics with the taste cells located in taste buds of the oro-pharyngeal cavity. In particular, they may express molecules of the chemoreceptorial cascade (such as trans-membrane taste receptors, the G-protein gustducin
Gustducin
Gustducin is a G protein associated with basic taste and the gustatory system. Due to its relatively recent discovery and isolation, not all is known about its nature and its associated pathways. It is known that it plays a large role in the transduction of bitter, sweet and umami stimuli and...
, PLCbeta2, IP3R3, TRPM5
TRPM5
Transient receptor potential cation channel subfamily M member 5 , also known as long transient receptor potential channel 5 is a protein that in humans is encoded by the TRPM5 gene....
). Morphologically, the elements of SCCs are polymorphic. Some of them have an apical tuft of rigid microvilli (brush cells). Other elements have secretory exocrine granules and others may have endocrine differentiation. Often these elements are innervated. In the upper respiratory system the SCCs are contacted by the sensory endings of trigeminal nerve fibers (SubP and CGRP immunoreactive).
The SCCs of the aquatic vertebrates play a role in food search and predator avoidance. The functional role of the SCCs located in internal organs of mammals is unknown also if several hypotheses have been advanced. In nasal cavity, SCCs operate as sentinels being involved in detection of irritants and are important in the protection of the airway.