Particle arrays on insect nerve membranes.

Freeze-fracture studies of Lepidopteran antennae have revealed the presence of orthogonal arrays of particles on antennal nerve membranes. Initial impressions were that several different arrays were present. Optical diffraction was used to examine the arrays on the electron micrograph negatives. This technique showed that all the arrays were derived from the same basic structure, suggesting that the superficial differences in appearance were due to shadowing effects. The particles are arranged in a lattice with spacings of 10.7 nm X 9.1 nm. The arrays are not clear-cut but tend to break up, producing a disorganized region around their edges. The particles are shown to have depressions in them. However, the evidence available suggests that the arrays do not have the other characteristics of gap junctions. The arrays appear not to be present on most of the nerve membrane faces, occurring only in localized regions of the nerve membranes where they are present in large numbers. This suggests that the arrays may have a specialized local function.