The research is designed to increase our understanding of non-nervous epithelial tissue capable of spontaneous electrical activity and of solute transport by epithelia. Spontaneous activity is usually under the control of an endogenous pacemaker and involves myogenic conduction. Because of the relative primitive nature of myogenic conduction systems, they are best studied in invertebrates and in embryological vertebrate tissue. With increased knowledge of developing vertebrate tissue or continually growing invertebrate epithelia, we will be able to more thoroughly understand embryonic development in man. Since ions are important in electrogenesis, self-regulation of ionic concentrations in epithelia is also being studied. Epithelial tissue are being studied in two systems. Separated hydra epithelial cell layers are being studied to determine which of the two cell layers is responsible for the electrophysiological properties of intact animals; and the transport across flattened tissue sheets of hydra are being studied. Solute transport across the wall of embryonic and adult mouse epithelia is also being studied. BIBLIOGRAPHIC REFERENCES: M. Macklin (1976) The Effect of Urethan on Hydra, Biological Bulletin, 150:442-452. M. Macklin and G. Westbrook (1976) Ionic Requirements of Transepithelial Potentials in Isolated Cell Layers of Hydra in Coelenterate Ecology and Behavior, G. O. Mackie, Ed. (Plenum, New York) 715-728.