[Comparative morphology of intercellular contacts]

The data of the literature on ultrastructure of the intercellular contacts in main types of Metazoa (Spongia, Coelenterata, Plahelminthes, Annelides, Mollusca, Arthropods, Echinodermata and Chordata) have been analysed in view of systemic organology. Function of the intercellular contacts is considered as system-forming. Three aspects in the system-forming function of the intercellular contacts have been determined--adhesion, communication and isolation. Increase in the system-forming function of these structures has been demonstrated to be the main regularity in the evolution of the intercellular contacts in animals; this point is proved by analysing all the three aspects. A suggestion is made on the source for appearance of tight junctions.