The membranous labyrinth lies ('neloHed in the very hard petroua part, of the temporal bone and, as the name implies. it,s structure is extremely compl('x. This may explain why our knowledge of this organ and the vestibular sensory regions within it, is not yet satisfactory. In recent years the rapid development of space research has provided a power ful stimulus to our interest in the vestibular apparatus. This has found expression in annual symposia, in which the role of thc vestibular organs in the exploration of space is discussed. However, little is known as yet about the inflU

I. Introduction

II. Material and Methods
III. Form and Interconnections of the Vestibular Ducts and Sacs
IV. The Vestibular Nerve and Its Ramifications
V. Structure of the Vestibular Sensory Epithelia
VI. Morphological Polarization of the Sensory Cells
VII. Innervation of the Vestibular Sensory Epithelia
VIII. Form and Structure of the Statoconial Membranes and the Cupulae
IX. General Discussion
X. Summary
Acknowledgement
References.