gap junctions

1.0 INTRODUCTION

During the course of evolution of single cells to multicellular organisms, new genes and functions were developed to assure coordinated regulation of cellular processes within these more complex entities. In multi-cellular organisms a delicate balance of regulatory and integrative mechanisms has to be achieved in order to maintain a relatively stable internal environment in the face of variations in the external conditions. This state of equilibrium, termed homeostasis, is controlled by three major communication processes: 1) extracellular communication, 2) intracellular communi-cation, and 3) intercellular communication. The integrated control of these three communication routes permits an organism to proliferate, to differentiate, to undergo apoptosis (programmed cell death) and to adapt/respond to stimuli (Trosko and Ruch, 1998).
It has been suggested that the gain in ability of more complex organisms to regulate cell growth, differentiation and apopto...