A freeze-fracture study of tight junctions in the pars convoluta and pars recta of the renal proximal tubule

1978 ◽  
Vol 186 (1) ◽  
Author(s):  
B. Roesinger ◽  
A. Schiller ◽  
R. Taugner
Keyword(s):  
Proximal Tubule ◽  
Tight Junctions ◽  
Freeze Fracture ◽  
Renal Proximal Tubule ◽  
Pars Recta ◽  
Fracture Study ◽  
Pars Convoluta

scholarly journals A freeze-fracture study on the developing satellite cells of spinal ganglia in the chick embryo

1988 ◽  
Vol 46 (1) ◽  
pp. 6-9
Author(s):  
Claudio A. Ferraz de Carvalho ◽  
Ciro F. da Silva
Keyword(s):  
Chick Embryo ◽  
Gap Junctions ◽  
Tight Junctions ◽  
Small Groups ◽  
Satellite Cells ◽  
Freeze Fracture ◽  
Fracture Analysis ◽  
Spinal Ganglia ◽  
Pinocytotic Vesicles ◽  
Fracture Study

A freeze-fracture analysis of the satellite cells of spinal ganglia of the chick embryo was performed in 8 successive stages of development, from the 5th incubation day to hatching. The characteristic laminar disposition of the cells were first observed on the 7th day. Tight junctions were found at the 20th incubation day. Small groups or irregular aggregates of particles, but not gap junctions, were described on the 7th and 8th days. Pinocytotic vesicles were pointed out in the different stages considered.

Radioimmunoassay Measurement of Urinary Ligandin Excretion in Nephrotoxin-Treated Rats

1979 ◽  
Vol 56 (5) ◽  
pp. 419-426 ◽  
Author(s):  
N. M. Bass ◽  
R. E. Kirsch ◽  
S. A. Tuff ◽  
J. A. Campbell ◽  
J. S. Saunders
Keyword(s):  
Proximal Tubule ◽  
Time Course ◽  
Potassium Dichromate ◽  
Tubular Damage ◽  
Moderate Increase ◽  
Normal Range ◽  
Pars Recta ◽  
Normal Urine ◽  
Renal Tubular ◽  
Pars Convoluta

1. A radioimmunoassay was used to establish normal urine excretion of ligandin, a renal tubular protein, in rats, and to study the pattern of ligandin excretion after nephrotoxin administration. 2. Validation of radioimmunoassay measurement of ligandin in urine is described. A normal range of 2–46 ng/h was obtained for ligandin excretion in rats (n = 24). 3. Mercuric chloride (HgCl2; 10 mg/kg) administration resulted in a significant increase in ligandin excretion within 6 h, preceding the onset of significant azotaemia. Serum ligandin concentrations were raised after 12 h, while renal ligandin concentration fell to 30% of control values by 24 h. 4. Rats given HgCl2 (5 mg/kg) developed massive ligandinuria between 6 and 12 h, which declined to normal values by 72 h. Potassium dichromate (K2Cr2O7; 7 mg/kg) administration produced a comparatively moderate increase in ligandin excretion after 24 h. 5. The time course of ligandin excretion in HgCl2- and K2Cr2O7-treated rats correlated with the histological sequence of damage to the pars recta and pars convoluta of the proximal tubule respectively. 6. The results of this study confirm that renal ligandin is confined mainly to the pars recta of the proximal tubule, and small quantities of this protein are present in the pars convoluta. Radioimmunoassay provides a sensitive and specific means for measuring ligandin in urine and provides a valuable tool for the detection and study of renal tubular damage.

scholarly journals Tight-junctional strands first appear in regions where three cells meet in differentiating olfactory epithelium: a freeze-fracture study

1988 ◽  
Vol 89 (4) ◽  
pp. 495-505
Author(s):  
B.P. Menco
Keyword(s):  
Embryonic Development ◽  
Gap Junction ◽  
Tight Junctions ◽  
Olfactory Epithelium ◽  
Freeze Fracture ◽  
Subsequent Development ◽  
Epithelial Surface ◽  
Direction Parallel ◽  
Longitudinal Orientation ◽  
Fracture Study

Tight junctions of the olfactory epithelium of rat embryos were studied at the 14th day of gestation and during their subsequent development. Two different epithelial morphologies could be distinguished at the 14th gestational day. In one group of embryos the epithelial surface appeared undifferentiated, with tight-junctional strands found exclusively in regions where three cells met. The main orientation of these strands is in a direction parallel to the longitudinal orientation of the epithelial cells. These junctions resemble tight junctions that interconnect three cells, i.e. tricellular tight junctions, in that respect. However, unlike these the junctions mainly have single strands of particles, whereas tricellular junctions usually consist of paired strands of particles. Tight-junctional strands were completely absent in areas where two cells met. These areas, i.e. those of incipient bicellular tight junctions, had gap-junction-like aggregates of intramembranous particles. Another group of 14-day-old embryos displayed a differentiating olfactory epithelial surface with bicellular as well as tricellular tight-junctional strands. The latter ones were paired. Here too the tight-junctional belts displayed some gap-junction-like aggregates of particles, but there were considerably fewer of these than earlier. As one or the other tight-junctional appearance was always seen in a single freeze-fracture replica, it is reasonable to assume that the two tight-junctional appearances reflect a sequential pattern of differentiation peculiar to the whole surface of the olfactory epithelium, i.e. to surfaces of receptor cells as well as to surfaces of supporting cells. It would appear that, at the onset of olfactory epithelial differentiation, tight junctions first interconnect cells in regions where three cells meet and that tricellular strand formation precedes the formation of bicellular strands. When strands were present at the 14th day of embryonic development, their numbers were lower than those found later. However, strand packing, expressed as the density per micrometre of strands parallel to the epithelial surface, increased beginning at the 16th day of embryonic development.

Tight and gap junctions in the intestinal tract of tunicates (Urochordata): a freeze-fracture study

1986 ◽  
Vol 84 (1) ◽  
pp. 1-17
Author(s):  
N.J. Lane ◽  
R. Dallai ◽  
P. Burighel ◽  
G.B. Martinucci
Keyword(s):  
Gap Junctions ◽  
Tight Junctions ◽  
Thin Section ◽  
Intestinal Tract ◽  
Freeze Fracture ◽  
Intestinal Cells ◽  
Fracture Profile ◽  
Tracer Studies ◽  
Septate Junctions ◽  
Fracture Study

The intestinal tracts from seven different species of tunicates, some solitary, some colonial, were studied fine-structurally by freeze-fracture. These urochordates occupy an intermediate position phylogenetically between the vertebrates and the invertebrates. The various regions of their gut were isolated for examination and the junctional characteristics of each part investigated. All the species examined exhibited unequivocal vertebrate-like belts of tight-junctional networks at the luminal border of their intestinal cells. No septate junctions were observed. The tight junctions varied in the number of their component strands and the depth to which they extended basally, some becoming loose and fragmented towards that border. The junctions consisted of ridges or rows of intramembranous particles (IMPs) on the P face, with complementary, but offset, E face grooves into which IMPs sometimes fractured. Tracer studies show that punctate appositions, the thin-section correlate of these ridge/groove systems, are sites beyond which exogenous molecules do not penetrate. These junctions are therefore likely to represent permeability barriers as in the gut tract of higher chordates. Associated with these occluding zonular junctions are intermediate junctions, which exhibit no identifiable freeze-fracture profile, and macular gap junctions, characterized by a reduced intercellular cleft in thin section and by clustered arrays of P face particles in freeze-fractured replicas; these display complementary aggregates of E face pits. The diameters of these maculae are rarely very large, but in certain species (for example, Ciona), they are unusually small. In some tissues, notably those of Diplosoma and Botryllus, they are all of rather similar size, but very numerous. In yet others, such as Molgula, they are polygonal with angular outlines, as might be indicative of the uncoupled state. In many attributes, these various junctions are more similar to those found in the tissues of vertebrates, than to those in the invertebrates, which the adult zooid forms of these lowly chordates resemble anatomically.

Induction of ornithine decarboxylase immunoreactivity in the male mouse kidney following testosterone treatment: an axial heterogeneity in the proximal tubule

1993 ◽  
Vol 136 (1) ◽  
pp. 85-NP ◽  
Author(s):  
N. Koibuchi ◽  
S. Matsuzaki ◽  
H.-T. Ma ◽  
M. Sakai ◽  
S. Yamaoka
Keyword(s):  
Proximal Tubule ◽  
Ornithine Decarboxylase ◽  
Protein Level ◽  
Male Mouse ◽  
Subcutaneous Injection ◽  
Mouse Kidney ◽  
Luminal Surface ◽  
Testosterone Treatment ◽  
Pars Recta ◽  
Pars Convoluta

ABSTRACT The effect of testosterone on the activity of ornithine decarboxylase (ODC), its protein level and immunocytochemical distribution were examined in the mouse kidney. Male BALB C mice at 8 weeks of age were used throughout. Fourteen hours before death, they received a subcutaneous injection of testosterone (1 mg/animal) or solvent to measure renal ODC activity or to detect the distribution of ODC immunoreactivity in the kidney. Renal ODC activity and the content of the enzyme were markedly increased after testosterone treatment. Histologically, few cells that were obviously immunoreactive to ODC were observed in the control animals and in the testosterone-treated animals a marked increase in ODC immunoreactivity was observed only in the cortex. ODC immunoreactive cells were located diffusely in the proximal tubule. In the pars recta, cells were stained weakly and homogeneously, while in the pars convoluta, the luminal surface of the cells showed stronger immunoreactivity. Moreover, many granule-like particles that were strongly ODC immunoreactive were observed inside the lumen of the pars convoluta. These results show that testosterone treatment induces an increase in ODC content in certain cells located in the proximal tubule of the cortex. Journal of Endocrinology (1993) 136, 85–89

Micropuncture study of tubular transport of urate and PAH in the pig kidney

1980 ◽  
Vol 239 (2) ◽  
pp. F107-F112 ◽  
Author(s):  
F. Roch-Ramel ◽  
F. White ◽  
L. Vowles ◽  
H. A. Simmonds ◽  
J. S. Cameron
Keyword(s):  
Proximal Tubule ◽  
Transport Mechanism ◽  
Fractional Excretion ◽  
Competitive Inhibitor ◽  
Pig Kidney ◽  
Tubular Transport ◽  
Pars Recta ◽  
Micropuncture Study ◽  
Plasma Urate ◽  
Pars Convoluta

At physiological plasma urate concentration (Purate) (0.05 mg/dl), net secretion of urate occurred in the convoluted part of the proximal tubule of micropunctured anesthetized pigs. The fraction of filtered urate delivered to the point of micropuncture ((TF/P)urate/(TF/P)polyfructosan) was 4.8 +/- 0.5 (mean +/- SE, n =10). Urate was reabsorbed from lower tubular segments, since the fractional excretion of urate (FEurate) was only 2.1. Saturation of secretion as well as reabsorption occurred at Purate of 1.6 mg/dl. p-Aminohippurate (PAH) secretion also occurred mainly in the pars convoluta of the proximal tubule: (TF/P)PAH/(TF/P)polyfructosan was 4.0 +/- 0.4 (n = 11), whereas the FEPAH was 4.5 +/- 0.5 (n = 5). Thus, the pars recta does not contribute significantly to the net secretion of either urate or PAH. PAH was a competitive inhibitor of urate secretion. At a PPAH of 60 mg/dl there was overall net reabsorption of urate. Accordingly, in the pig PAH and urate seem to be secreted by the same transport mechanism.

Tight junctions of human keratinocytes in primary culture: A freeze-fracture study

1983 ◽  
Vol 82 (3) ◽  
pp. 309-313 ◽  
Author(s):  
Yasuo Kitajima ◽  
Kiyomi Eguchi ◽  
Tadao Ohno ◽  
Shunji Mori ◽  
Hideo Yaoita
Keyword(s):  
Primary Culture ◽  
Tight Junctions ◽  
Freeze Fracture ◽  
Human Keratinocytes ◽  
Fracture Study
Sign in / Sign up

Export Citation Format

Share Document