DECREASED DENSITIES OF INTRAMEMBRANOUS PARTICLES AND CYTOCHEMICALLY DETECTABLE CHOLESTEROL IN MICROVILLI OF STARVED RAT ENTEROCYTES

1998 ◽  
Vol 22 (3) ◽  
pp. 177-183 ◽  
Author(s):  
A WAHEED
Keyword(s):  
Intramembranous Particles ◽  
Rat Enterocytes

Freeze-etch observations on the tight junctions of sertoli cells grown in organ culture with FSH

1978 ◽  
Vol 36 (2) ◽  
pp. 340-341
Author(s):  
Rita Meyer ◽  
Zoltan Posalaky ◽  
Dennis Mcginley
Keyword(s):  
Organ Culture ◽  
Tight Junctions ◽  
Sertoli Cell ◽  
Germ Cells ◽  
Sertoli Cells ◽  
Barrier Function ◽  
Cell Junction ◽  
Intramembranous Particles ◽  
Junctional Complexes ◽  
Oriented Parallel

The Sertoli cell tight junctional complexes have been shown to be the most important structural counterpart of the physiological blood-testis barrier. In freeze etch replicas they consist of extensive rows of intramembranous particles which are not only oriented parallel to one another, but to the myoid layer as well. Thus the occluding complex has both an internal and an overall orientation. However, this overall orientation to the myoid layer does not seem to be necessary to its barrier function. The 20 day old rat has extensive parallel tight junctions which are not oriented with respect to the myoid layer, and yet they are inpenetrable by lanthanum. The mechanism(s) for the control of Sertoli cell junction development and orientation has not been established, although such factors as the presence or absence of germ cells, and/or hormones, especially FSH have been implicated.

scholarly journals STa-induced translocation of protein kinase C from cytosol to membrane in rat enterocytes

2001 ◽  
Vol 204 (1) ◽  
pp. 65-69 ◽  
Author(s):  
Uma Ganguly ◽  
Alok Ghosh Chaudhury ◽  
Arindam Basu ◽  
Parimal C Sen
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Kinase C ◽  
Rat Enterocytes

scholarly journals Imaging of intramembranous particles in frozen-hydrated cells (Saccharomyces cerevisiae ) by high resolution cryo SEM

Scanning ◽  
1990 ◽  
Vol 12 (6) ◽  
pp. 300-307 ◽  
Author(s):  
P. Walther ◽  
J. Hentschel ◽  
P. Herter ◽  
T. Müller ◽  
K. Zierold
Keyword(s):  
Saccharomyces Cerevisiae ◽  
High Resolution ◽  
Intramembranous Particles

Stages in the assembly of pleated and smooth septate junctions in developing insect embryos

1982 ◽  
Vol 56 (1) ◽  
pp. 245-262 ◽  
Author(s):  
N.J. Lane ◽  
L.S. Swales
Keyword(s):  
Embryonic Development ◽  
Freeze Fracture ◽  
Organizational Capacity ◽  
Intramembranous Particle ◽  
Septate Junctions ◽  
Thin Sections ◽  
Intramembranous Particles ◽  
Initial Event ◽  
Random Arrays ◽  
Insect Embryos

The stages that occur during the assembly of both pleated and smooth septate junctions in developing insect tissues have been examined. The oesophagus and mid-gut of the embryonic moth, and the oesophagus and central nervous system (CNS) of the locust embryo, have been investigated in thin sections and by freeze-fracture during the course of membrane biogenesis. The smooth septate junctions developing between the lateral borders of the mid-gut exhibit, in the early stages, individual intramembranous particles becoming aligned into short ridges. These ultimately migrate over the membrane face and fuse into longer arrays, which become stacked in parallel with other ridges to form the characteristic mature form of the junction just before hatching. Pleated septate junctions occur between the cells both of the oesophagus and of the perineurium, which ensheathes the neurones and the neuroglial cells in the locust CNS; these are also fully formed by the end of embryonic development. The pleated junctions appear to be assembled during the later stages of CNS or gut differentiation, arising first in embryos about two-thirds of the way through development. During their maturation, the initial event seems to be a membrane depression in the P face, which occurs in patches over the presumptive junctional membrane. Into these depressed regions or ‘formation-plaque’ areas, 8–10 nm particles appear to be inserted intramembranously in apparently random arrays. These particles are the most common elements but larger particles are also present; the former ultimately become aligned in a row. With time, other intramembranous particles come to lie in rows parallel to the original one. By hatching, the typical undulating stacks of parallel intramembranous particle rows are fully formed. Gap junctions also form between the same perineurial or oesophageal cells, usually before, but in some cases at the same time, or just after, the septate junctions have been assembled. Tricellular associations between cells also appear around the same time in embryonic development. The simultaneous assembly of these different junctions reflects a high degree of organizational capacity at the membrane level.

Comparative Aspects Of The Occluding Junctions In The Pulmonary And Bronchial Microcirculation

1981 ◽  
Author(s):  
H Bartels
Keyword(s):  
Endothelial Cells ◽  
Plasma Membrane ◽  
Freeze Fracture ◽  
Continuous System ◽  
Intramembranous Particles ◽  
Vasoactive Substances ◽  
Cell Biol ◽  
Occluding Junctions ◽  
Pulmonary Microcirculation

Compared with the pulmonary microcirculation the bronchial microcirculation reacts with a large increase in permeability after administration of vasoactive substances (Pietra et al., Cire. Res. 29, 323, 1971). Thus the occluding junctions between the endothelial cells of the rat pulmonary and bronchial microcirculation were investigated by means of freeze-fracture replicas in order to establish differences in their substructure which could be responsible for the different permeability properties. The prevailing feature of the occluding junctions between the endothelial cells of the pulmonary microvascular bed was a continuous system of anastomosing membrane foldings,carrying rows of intramembranous particles, which were usually located on face E of the split plasma membrane. This type of occluding junction is characteristic of capillaries (Simionescu et al., J. Cell Biol. 67, 863, 1975) . In the bronchial microcirculation many of the endothelial occluding junctions showed discontinuous assemblies of membrane foldings, which were lacking particles on face E. This type of “open” junction is typically localized at the venular end of the microvascular bed and susceptible to vasoactive substances (Simionescu et al., J. Cell Biol. 78, 27, 1978). It is suggested that the different permeability properties of the pulmonary and bronchial microcirculation is due to the large amount of postcapillary venules with their morphologically and functionally characteristic occluding junctions.

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