Evidence for an organized lattice in the intercellular space of vestibular sensory cat epithelia.

The intracellular space between sensory hair cells and nerve endings and between supporting cells of the vestibular epithelia in the cat contains a fine network of microstructures arranged obliquely between the cell membranes of adjacent cells. In situ immersion-perfusion fixation, electron microscopy complemented by lanthanum negative-contrast and freeze-fracture methods suggest that these intercellular structures are tubular with an external diameter between 3 and 6 nm and an internal diameter of 1.5 nm. They could serve as intercytoplasmic tunnels. We discuss the evidence concerning the analogy between the present microchannels and the passageways regularly arranged in the intercellular space of gap-junctions which would permit the transport of low molecular weight substances from one cell to other.