title: Electron microscopic studies of coated membranes in two types of gill epithelial cells of lamprey.
abstract: Coated membranes in two types of gill epithelial cell of adult lamprey, Lampetra japonica, were studied by electron microscopy. The type 3 gill epithelial cells possess well-developed microvilli or microfolds, apical vesicles and abundant mitochondria. The cytoplasmic surface of the microvillous plasma membrane is covered by a coat of regularly spaced particles with a center-to-center distance of about 15 nm. Each particle consists of a bulbous free end, about 10 nm in diameter, and a connecting piece, about 5 nm long. Apical vesicles are covered by a surface coat which consists of fine filamentous material but lack any special coating on their cytoplasmic surface. The type 4 cells (chloride cells) are characterized by apical vesicles, abundant mitochondria and cytoplasmic tubules. These tubules possess a coat on their luminal surface which consists of spirally wound parallel rows of electron-dense materials. The rows are about 16 nm apart and wound at a pitch of about 45 degrees. The cytoplasmic surface of these tubules does not display a special coat. These coated membranes are assumed to be the sites of active ion transport across the plasma membrane. In particular, particles in type 3 cells and linear coat materials in chloride cells may be either loci of transport enzymes or energy generating systems. Apical vesicles lack any coating on their cytoplasmic surface but a fine filamentous coat is present on their luminal surface. They contain "intraluminal vesicles" and are continuous with apical ends of cytoplasmic tubules.
mesh_terms: D000818:Animals; D004847:Epithelial Cells; D004848:Epithelium / Q000648:ultrastructure; D005399:Fishes / Q000033:anatomy & histology*; D005880:Gills / Q000502:physiology / Q000648:ultrastructure*; D007798:Lampreys / Q000033:anatomy & histology*; D008854:Microscopy, Electron; D014882:Water-Electrolyte Balance