Interstitial cell of Cajal
Encyclopedia
The Interstitial cell of Cajal (ICC) is a type of interstitial cell
found in the gastrointestinal tract
that serves as a pacemaker which creates the basal electrical rhythm
leading to contraction
of the smooth muscle
(peristalsis
& Segmentation).
Many types of smooth muscle tissues have now been shown to contain ICC, but with few exceptions the function of these cells is not known and is currently an area of active research
. An international society (International Society for ICC, www.isicc.org) has recently been formed to provide a forum to discuss research in ICC in a variety of tissues.
These cells are derived from mesoderm
.
pacemakers and generate spontaneous electrical slow waves
in the gastrointestinal (GI) tract. Electrical slow waves spread from ICC to smooth muscle cells and the resulting depolarization initiates calcium ion entry and contraction. Slow waves organize gut contractions into phasic contractions that are the basis for peristalsis
and segmentation
.
ICC also mediate neural input from enteric motor neuron
s. Animals lacking ICC have greatly reduced responses to the neurotransmitter
acetylcholine
, released from excitatory motor neurons, and to the transmitter
, nitric oxide
, released from inhibitory motor neurons. Loss of ICC in disease
, therefore, may interrupt normal neural control of gastrointestinal (GI) contractions and lead to functional GI disorders, such as irritable bowel syndrome
.
ICC also express mechano-sensitive mechanisms that cause these cells to respond to stretch. Stretching GI muscles can affect the resting potential
s of ICC and affect the frequency of pacemaker activity.
ICC are also critical in the propagation of electrical slow waves. ICC form a network through which slow wave activity can propagate actively. If this network is broken, then 2 regions of muscle will function independently.
, a Spanish
pathologist and Nobel laureate.
Interstitial cell
Interstitial cell refers to any one of a number of different types of cells characterized by their interstitial nature Examples include:...
found in the gastrointestinal tract
Gastrointestinal tract
The human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. ....
that serves as a pacemaker which creates the basal electrical rhythm
Basal electrical rhythm
The Basal or Basic electrical rhythm or electrical control activity determines the frequency of the contractions in the gastrointestinal tract.-Physiology:...
leading to contraction
Muscle contraction
Muscle fiber generates tension through the action of actin and myosin cross-bridge cycling. While under tension, the muscle may lengthen, shorten, or remain the same...
of the smooth muscle
Smooth muscle
Smooth muscle is an involuntary non-striated muscle. It is divided into two sub-groups; the single-unit and multiunit smooth muscle. Within single-unit smooth muscle tissues, the autonomic nervous system innervates a single cell within a sheet or bundle and the action potential is propagated by...
(peristalsis
Peristalsis
Peristalsis is a radially symmetrical contraction and relaxation of muscles which propagates in a wave down the muscular tube, in an anterograde fashion. In humans, peristalsis is found in the contraction of smooth muscles to propel contents through the digestive tract. Earthworms use a similar...
& Segmentation).
Many types of smooth muscle tissues have now been shown to contain ICC, but with few exceptions the function of these cells is not known and is currently an area of active research
Research
Research can be defined as the scientific search for knowledge, or as any systematic investigation, to establish novel facts, solve new or existing problems, prove new ideas, or develop new theories, usually using a scientific method...
. An international society (International Society for ICC, www.isicc.org) has recently been formed to provide a forum to discuss research in ICC in a variety of tissues.
These cells are derived from mesoderm
Mesoderm
In all bilaterian animals, the mesoderm is one of the three primary germ cell layers in the very early embryo. The other two layers are the ectoderm and endoderm , with the mesoderm as the middle layer between them.The mesoderm forms mesenchyme , mesothelium, non-epithelial blood corpuscles and...
.
Role in slow wave activity
ICC serve as electricalElectricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...
pacemakers and generate spontaneous electrical slow waves
Slow wave threshold
In physiology, the slow-wave threshold is the potential which must be reached before a slow wave can be propagated in smooth muscle. Slow waves cause no smooth muscle contraction.-Gastrointestinal smooth muscle:...
in the gastrointestinal (GI) tract. Electrical slow waves spread from ICC to smooth muscle cells and the resulting depolarization initiates calcium ion entry and contraction. Slow waves organize gut contractions into phasic contractions that are the basis for peristalsis
Peristalsis
Peristalsis is a radially symmetrical contraction and relaxation of muscles which propagates in a wave down the muscular tube, in an anterograde fashion. In humans, peristalsis is found in the contraction of smooth muscles to propel contents through the digestive tract. Earthworms use a similar...
and segmentation
Segmentation contractions
Segmentation contractions are a type of gastric motility.Unlike peristalsis, which predominates in the esophagus, segmentation contractions occur in the large intestine and small intestine, while predominating in the latter...
.
Frequency of ICC pacemaker cells
The frequency of ICC pacemaker activity differs in different regions of the GI tract:- 3 per minute in the stomachStomachThe stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...
- 12 per minute in the duodenumDuodenumThe duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms anterior intestine or proximal intestine may be used instead of duodenum...
- 10 per minute in the ileumIleumThe ileum is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine may be used instead of ileum.The ileum follows the duodenum...
- 3 per minute in the colonColon (anatomy)The colon is the last part of the digestive system in most vertebrates; it extracts water and salt from solid wastes before they are eliminated from the body, and is the site in which flora-aided fermentation of unabsorbed material occurs. Unlike the small intestine, the colon does not play a...
ICC also mediate neural input from enteric motor neuron
Motor neuron
In vertebrates, the term motor neuron classically applies to neurons located in the central nervous system that project their axons outside the CNS and directly or indirectly control muscles...
s. Animals lacking ICC have greatly reduced responses to the neurotransmitter
Neurotransmitter
Neurotransmitters are endogenous chemicals that transmit signals from a neuron to a target cell across a synapse. Neurotransmitters are packaged into synaptic vesicles clustered beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to...
acetylcholine
Acetylcholine
The chemical compound acetylcholine is a neurotransmitter in both the peripheral nervous system and central nervous system in many organisms including humans...
, released from excitatory motor neurons, and to the transmitter
Cell signaling
Cell signaling is part of a complex system of communication that governs basic cellular activities and coordinates cell actions. The ability of cells to perceive and correctly respond to their microenvironment is the basis of development, tissue repair, and immunity as well as normal tissue...
, nitric oxide
Nitric oxide
Nitric oxide, also known as nitrogen monoxide, is a diatomic molecule with chemical formula NO. It is a free radical and is an important intermediate in the chemical industry...
, released from inhibitory motor neurons. Loss of ICC in disease
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
, therefore, may interrupt normal neural control of gastrointestinal (GI) contractions and lead to functional GI disorders, such as irritable bowel syndrome
Irritable bowel syndrome
Irritable bowel syndrome is a diagnosis of exclusion. It is a functional bowel disorder characterized by chronic abdominal pain, discomfort, bloating, and alteration of bowel habits in the absence of any detectable organic cause. In some cases, the symptoms are relieved by bowel movements...
.
ICC also express mechano-sensitive mechanisms that cause these cells to respond to stretch. Stretching GI muscles can affect the resting potential
Resting potential
The relatively static membrane potential of quiescent cells is called the resting membrane potential , as opposed to the specific dynamic electrochemical phenomena called action potential and graded membrane potential....
s of ICC and affect the frequency of pacemaker activity.
ICC are also critical in the propagation of electrical slow waves. ICC form a network through which slow wave activity can propagate actively. If this network is broken, then 2 regions of muscle will function independently.
Pathology
ICCs are thought to be the cells from which gastrointestinal stromal tumours (GISTs) arise. Also, abnormalities in the ICC network is one cause of chronic intestinal pseudo-obstruction.Eponym
The interstitial cells of Cajal are named after Santiago Ramón y CajalSantiago Ramón y Cajal
Santiago Ramón y Cajal ForMemRS was a Spanish pathologist, histologist, neuroscientist, and Nobel laureate. His pioneering investigations of the microscopic structure of the brain were original: he is considered by many to be the father of modern neuroscience...
, a Spanish
Spanish people
The Spanish are citizens of the Kingdom of Spain. Within Spain, there are also a number of vigorous nationalisms and regionalisms, reflecting the country's complex history....
pathologist and Nobel laureate.
External links
- Overview of ICCs - unr.edu.