Gap junction pleiomorphism in the root system of the rhizocephalans (Arthropoda: Crustacea)

We have studied gap junctions in the root system of four different species of rhizocephalans (Arthropoda: Crustacea) using freeze-fracture. Numerous and often very extensive gap junctions are present between the root cells. They are of the characteristic E-type also found in other arthropods. Large junctional particles (ca. 13 nm) are located predominantly on the E-face, while complementary pits and a few dislocated particles are present on the P-face. The gap junctions show a remarkable pleiomorphism. Small macular gap junctions with rather densely packed particles, larger irregularly shaped gap junctions, often forming bands with intervening particle-free membrane domains, and gap junctions with widely dispersed particles are observed. These features are documented both in material after conventional preparation including glutaraldehyde fixation and glycerol cryoprotection and in material frozen directly in a nitrogen slush without any preceding preparation, and are discussed in relation to possible functional significance.