Distribution of canalicular reticulum in Deiters cells and pillar cells of gerbil cochlea

Abstract

Postfixation with an osmium tetroxide-potassium ferrocyanide solution revealed in supporting cells in the organ of Corti a network of canaliculi termed canalicular reticulum (CR). In Deiters cells (DCs), the CR filled cytosol at the base of the phalanx and under plasmalemma apposed to either the outer hair cells' (HCs) basal surface or nerve terminals. From these locations the CR, accompanied by dense fibrillar substance, descended along microtubule bundles and terminated by surrounding the rosette complex in the apical cytosol. Canalicular profiles protruding from the reticulum penetrated the loose meshwork comprising the periphery of the rosette complex to contact at intervals branches of the dense trabeculae that make up the core of the complex. This arrangement disclosed a structural and presumably functional relationship between outer HCs and the CR and rosette complex. Inner pillar cells (PCs) exhibited moderately abundant to sparse profiles of CR interspersed between microtubule bundles of the microtubule stalk that connected head and foot regions. More elaborate CR extended as a network upward from the top of the microtubule stalk part way into the head body and downward into a conical expansion of the stalk at the base of the cell. Cytosol on the medial side of the basal microtubule expansion contained abundant CR which in conjunction with CR between basal microtubule bundles lay situated for possible uptake of ions or neurotransmitter released from numerous adjoining nerves. CR in outer PCs resembled that in inner PCs but appeared less prevalent in the head and foot regions and did not occur in cytosol beside the basal microtubule stalk. Characteristically small Golgi complexes accompanied the reticulum in DCs and were prevalent in the upper regions but absent in the mid and lower part of inner PCs. Short cisternae in the Golgi stacks associated with CR contrasted with the lengthier cisternae in the complexes infrequently observed in cytosol outside the microtubule stalk of inner PCs.