Small vascular units consisting of an arteriole, its capillaries, and the emerging venule (ACV units) were identified in the rat omentum and mesentery. They were fixed in situ and processed for electron microscopy either as whole units or as dissected segments. Systematic examination of the latter (in thin sections, as well as in freeze-cleaved preparations) showed that the intercellular juncti...

Lens epithelial cells communicate with two different cell types. They communicate with other epithelial cells via gap junctions on their lateral membranes, and with fiber cells via junctions on their apices. We tested independently these two routes of cellcell communica t ion to determine if t reatment with a 90% CO2-equilibrated medium caused a decrease in junctional permeability; the transfer...

Electrotonic coupling of cardiac myocytes at gap junctions may influence patterns of conduction in myocardium. To delineate the three-dimensional structure and distribution of intercellular junctions, we analyzed serial ultrathin sections of canine myocardium with transmission electron microscopy and disaggregated myocytes with scanning electron microscopy. Morphometric analysis of left ventric...

Structural evidence is presented which suggests that gap junctions between lens fibers are adapted to remain in a low-resistance physiological state, under conditions which switch gap junctions in other tissues to a high-resistance state. The lens gap junction subunits (connexons) do not crystallize in the membrane plane in response to fixation, anoxia, lens damage, or homogenization and isolat...

Gap junctions serve many important roles in various tissues, but their abundance and diversity in neurons is only beginning to be understood. The tracer Neurobiotin has revealed many different networks interconnected by gap junctions in retina. We compared the relative permeabilities of five different retinal gap junctions by measuring their permeabilities to a series of structurally related tr...

Reversible crystallization of intramembrane particle packings is induced in gap junctions isolated from calf lens fibers by exposure to 3 x 10(-7) M or higher [H+] (pH 6.5 or lower). The changes from disordered to crystalline particle packings induced by low pH are similar to those produced in junctions of intact cells by uncoupling treatments, indicating that H+, like divalent cations, could b...

Striatal fast-spiking (FS) interneurons are interconnected by gap junctions into sparsely connected networks. As demonstrated for cortical FS interneurons, these gap junctions in the striatum may cause synchronized spiking, which would increase the influence that FS neurons have on spiking by the striatal medium spiny (MS) neurons. Dysfunction of the basal ganglia is characterized by changes in...

Axon specification is a critical step in neuronal development, and the function of glial cells in this process is not fully understood. Here, we show that C. elegans GLR glial cells regulate axon specification of their nearby GABAergic RME neurons through GLR-RME gap junctions. Disruption of GLR-RME gap junctions causes misaccumulation of axonal markers in non-axonal neurites of RME neurons and...

functional asymmetries of myelinated branches in the frog muscle spindle. A study of the permeability of the outer capsule of the frog muscle spindle to potassium ions using ion·sensitive microelectrodes. Introduction Gap junctions have been considered to be responsible for cell-cell communization and are found where electrical coupling or metabolic cooperation is present. 1,2) Many extensive g...

Neurons in mammalian brains are heavily interconnected by specialized junctions called chemical synapses. At chemical synapses, signals are transmitted rather indirectly between connected neurons with some delay. Recent studies have revealed additional channels for neuronal communication, that is, gap junctions. As electrical signals are directly transmitted through gap junctions without delay,...