Ball, E.R., Matsuda, M.M., Dye, L., Hoffmann, V., Zerfas, P.M., Szarek, E., Rich, A., Chitnis, A.B., and Stratakis, C.A. (2012) Ultra-structural identification of interstitial cells of Cajal in the zebrafish Danio rerio. Cell and tissue research. 349(2):483-491.
The interstitial cells of Cajal (ICCs) are important mediators of gastrointestinal (GI) motility because of their role as
pacemakers in the GI tract. In addition to their function, ICCs are also structurally distinct cells most easily identified
by their ultra-structural features and expression of the tyrosine kinase receptor c-KIT. ICCs have been described in mammals,
rodents, birds, reptiles, and amphibians, but there are no reports at the ultra-structural level of ICCs within the GI tract
of an organism from the teleost lineage. We describe the presence of cells in the muscularis of the zebrafish intestine; these cells have similar features to ICCs in other vertebrates. The ICC-like cells are associated
with the muscularis, are more electron-dense than surrounding smooth muscle cells, possess long cytoplasmic processes and mitochondria, and are
situated opposing enteric nervous structures. In addition, immunofluorescent and immunoelectron-microscopic studies with antibodies
targeting the zebrafish ortholog of a putative ICC marker, c-KIT (kita), showed c-kit immunoreactivity in zebrafish ICCs.
Taken together, these data represent the first ultra-structural characterization of cells in the muscularis of the zebrafish Danio rerio and suggest that ICC differentiation in vertebrate evolution dates back to the teleost lineage.