An unusual architecture of occluding junctions between surface cells in teleost ovarian follicles (Plecoglossus...

An unusual architecture of occluding junctions between surface cells in teleost ovarian follicles was observed by electron microscopy, by using the freeze-fracture technique. On the P-face, double strands of intramembraneous particles are observed. A narrow furrow-like gap is recognized between two rows of particles in such double strands. On the E-face, two types of grooves can be distinguished. Type I groove consists of a wide furrow. Type II groove, which appears to be sequent to type I groove, consists of a pair of "sub-grooves" running parallel. Further, a row of particles appears to be located in the bottom of type I groove or between two "sub-grooves" of type II groove. These observations suggest that the double strands on the P-face are registered with the grooves (type I or type II) on the complementary E-face and that a row of particles on the E-face is registered with a furrow-like region between two rows in the double strands on the P-face. In other words, a single unit of the juncture of the present occluding junction is thought to consist of triplicated junctional strands.