I wish to thank the following persons for their dedicated work and help during the performance of this Ph. D work. Prof. Dr. Jacob S. Ishay of the Department of Physiology and Pharmacology of the Sackler School of Medicine of Tel-Aviv University for his dedicated help in developing the research subject and for his advise since then. Prof. Dr. F. W. J. Albers, head of the department of Otolaryngology of the Academic Hospital of the University of Groningen for his help and understanding which enabled this presentation to take place at the Groningen University. Dr. W. L. Jongebloed of the Laboratory for Cell Biology and Electron Microscopy (LCEM) of the University of Groningen for his advise, help in preparing the various manuscripts for this thesis, initiative, promoting ideas in electron microscopy and in research. Mr. D. Kalicharan of the LCEM for his marvelous technical assistance which enabled the presentation of this electron microscopical work at a very high level. Dr. J. J. L. van der Want as head of the LCEM, Mrs. G. Noppert and Mr. P. van der Sijde for doing everything necessary in preparing the final stage of the thesis. My dear parents Haim and Hela Rosenzweig for their support during the long years of my education and my dear wife Lorena for her understanding and patience over the years of doing research. All those not mentioned in this expression of thanks for their help and understanding during all these years of research, which eventually lead to this thesis.