Arrays of particles in the sarcolemma of the distal accessory flexor muscle of the lobster.

Freeze-fracture of the distal accessory flexor muscle reveals the presence of randomly distributed arrays of P- and E-face particles. The particles are arranged in regularly spaced rows which parallel one another and, in general, the long axis of the muscle fiber. P- and E-face arrays differ in their structure and are apparently complementary. A model explaining the apparent interrelationship of the P- and E-face arrays is presented. The functional significance of the arrays is not known.