A comparative study on the intercellular canalicular system and intercellular junctions in the pancreatic islets of...

Intercellular junctions were studied in pancreatic islets of some rodents by electron microscopy of thin sections and freeze-fracture-replicas. Junctions between islet cells can be classified into three types: macula occludens, a combination of the macula occludens and gap junction, and gap junction. The first and second types are mainly located on the cell membrane near the intercellular canaliculus, while the third type is present independently of it. The development of these types of junctions varies considerably among animal species: in mice, guinea pigs and hamsters, the second and third types are frequent, but the first type is rarely seen. In Mongolian gerbils, diminutive elements of the three types are infrequently present. In rats, only the third type is developed. In addition to intercellular communication through gap junctions, the first and second types of junctions may incompletely discriminate the intercellular canalicular lumen, and regulate the microenvironment of the islet cell.