Morphological changes in tight junctions of Necturus maculosus proximal tubules undergoing saline diuresis.

Abstract

Tight junctions between epithelial cells are believed to control the paracellular diffusion of substances across epithelia. Epithelia in which tight junctions are poorly developed display a high paracellular electrical conductance, while those with extensive tight junctions show lower conductance values. We describe here a particular epithelium, that of the proximal tubules of the Necturua kidney, in which the development of the tight junctions varies in parallel with a change of paracellular electrical conductance. In control conditions, tight junctions between epithelial cells of the proximal tubules are more developed than in tubules undergoing saline diuresis, a situation which increases the conductance across the paracellular shunt pathway.

Perineurium of sciatic nerve in normal and diabetic rodents: freeze-fracture study of intercellular junctional complexes

“…It is known that the intercellular junctions behave as dynamic structures capable of responding to a number of stimuli. For example, an increase in the osmolarity of extracellular fluids may modulate the permeability of skin (Erlij & Martinez-Palomo, 1972) and kidney proximal tubule (Rawlins et al, 1975;Humbert et aL, 1976) in amphibians by modifying the tight junctional structure.…”

Mesaxonal membrane junction of myelinated nerve in the central and peripheral nervous system.

“…High concentration of ions and high osmotic pressure in the extracellular space have been known to induce a leaky structure of the tight junction in many kinds of epithelia (WADE et al, 1973;WADE and KARNOVSKY, 1974;HUMBERT et al, 1975;BOUCHAUD and BOUVIER, 1978). Therefore, the relatively high concentration of plasma proteins in the endoneurial interstitial fluid of peripheral myelinated nerves (OLSSON, 1975;VAN LIS and JENNEKENS, 1977) well reflects the leaky structure of the mesaxonal tight junction of the nerves.…”

“…The experimentally administered lanthanum penetrates easily into the peripheral myelin sheath (REVEL and HAMILTON, 1969). Furthermore, the extracellular fluid condition, which is known to modify the tight junctional structure (WADE et al, 1973;WADE and KARNOVSKY, 1974;HUMBERT et al, 1975;BOUCHAUD and BOUVIER, 1978), is different in the perifascicular space between the central and peripheral nerve (DAVSON, 1972;HARREVELD, 1972;VAN LIS and JENNEKENS, 1977).…”

Study of protein characteristics that influence entry into the cerebrospinal fluid of normal mice and mice with encephalitis.

“…It has, however, been postulated that the majority of proteins "leak" into the CSF passively through occasional pores present in the choroid plexus epithelium (28). These pores may be present within the somewhat leaky tight junctions between the epithelial cells (25) because tight junctions have been shown to control paracellular diffusion in other epithelia (29). The biphasic character of the albumin equilibration curves in normal mice suggests that two sites of protein entry may exist: one with a rapid equilibration (possibly choroid plexus) and another with a slower equilibration (possibly cerebral capillaries).…”