Tubular invaginations with caveolae and coated pits in the sinus endothelial cells of the rat spleen

1999 ◽  
Vol 112 (5) ◽  
pp. 351-358 ◽  
Author(s):  
K. Uehara ◽  
Masayuki Miyoshi
Keyword(s):  
Endothelial Cells ◽  
Coated Pits ◽  
Sinus Endothelial Cells

scholarly journals Fine Structure of the Red Pulp of the Spleen in Hereditary Spherocytosis

Blood ◽  
1972 ◽  
Vol 39 (1) ◽  
pp. 81-98 ◽  
Author(s):  
ZELMA MOLNAR ◽  
HENRY RAPPAPORT
Keyword(s):  
Endothelial Cells ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Hereditary Spherocytosis ◽  
Probable Mechanism ◽  
Hemoglobin Content ◽  
Sinus Endothelial Cells ◽  
In Transit ◽  
Conventional Light Microscopy ◽  
Red Pulp

Abstract The spleens from two children and one adult with hereditary spherocytosis were studied in the electron microscope. Stagnation of the erythrocytes within the splenic cords is attributable to their lack of plasticity as evidenced by the absence of bilobed, tailed, or squeezed forms in transit through the walls of the sinuses. In contrast to the sections studied by conventional light microscopy, the splenic sinuses in hereditary spherocytosis were not "empty," but contained red blood cells, the majority of which had lost their hemoglobin content. Cordal macrophages were increased in all three cases and were abundant in the splenic cords of the adult patient, causing a further impediment to the rapid passage of erythrocytes. Macrophages, and, to a lesser degree, sinus endothelial cells contained the products of hemoglobin breakdown. The macrophages showed active erythrophagocytosis. Sinus endothelial cells rarely contained intact red blood cells, but showed pronounced pinocytotic activity, a probable mechanism of hemoglobin incorporation. Platelets within the endothelial cells of the sinuses were much more frequently seen in the three cases of hereditary spherocytosis than in control spleens. The presence of ferritin in platelets suggests that they too may play a role in clearing the end products of hemolysis from the spleen.

scholarly journals Receptor distribution and the endothelial uptake of transcobalamin II in liver cell suspensions

Blood ◽  
1985 ◽  
Vol 65 (4) ◽  
pp. 795-802 ◽  
Author(s):  
R Soda ◽  
M Tavassoli ◽  
DW Jacobsen
Keyword(s):  
Electron Microscopy ◽  
Endothelial Cells ◽  
Liver Cell ◽  
Large Cell ◽  
Small Cell ◽  
Cell Suspensions ◽  
Cell Fraction ◽  
Coated Pits ◽  
Specificity Of Binding ◽  
Transcobalamin Ii

Abstract To determine the nature of binding of transcobalamin II (TC-II) to liver cells, we covalently coupled purified holo-TC-II to submicron latex minibeads using glutaraldehyde. Incubation of the probe with liver cell suspensions at 4 degrees C led to its binding by endothelial cells but not by hepatocytes or Kupffer cells, as visualized by scanning electron microscopy. At 37 degrees C, the probe was internalized by the endothelium through a system of coated pits and vesicles as shown by transmission electron microscopy. Inhibition studies by pre-incubation with excess native TC-II demonstrated the specificity of binding. Fractionation of these cell suspensions on metrizamide gradients yielded large cell (hepatocyte-rich) and small cell (endothelium-rich) fractions. The binding of the minibead probe occurred again exclusively on endothelial cells in the small cell fraction. 125I-labeled holo-TC-II also bound to the small cell but not to the large cell fraction. Binding was saturable (Ka, 0.225 X 10(9) mol/L-1) and receptor number was calculated to be 1.33 X 10(3) per cell. Time-dependent incubation of 125I-labeled TC-II with the endothelium-rich fraction led to its uptake, reaching a steady-state plateau at 4 degrees C. At 37 degrees C, however, the initial uptake was followed by gradual release of the label into the medium. We conclude that in the liver, holo-TC-II binds initially to endothelium, where it is internalized and is subsequently released probably to the interstitial space. Thus, the endothelium may play a fundamental role in the regulation of the uptake of TC-II by the liver.

scholarly journals Glucagon receptors in endothelial and Kupffer cells of mouse liver.

1988 ◽  
Vol 36 (9) ◽  
pp. 1081-1089 ◽  
Author(s):  
J Watanabe ◽  
K Kanai ◽  
S Kanamura
Keyword(s):  
Endothelial Cells ◽  
Plasma Membrane ◽  
Kupffer Cells ◽  
Mouse Liver ◽  
Intracellular Transport ◽  
Coated Pits ◽  
Sinusoidal Cells ◽  
Nonparenchymal Cells ◽  
Glucagon Receptors

To determine whether hepatic sinusoidal cells contain glucagon receptors and, if so, to study the significance of the receptors in the cells, binding of [125I]-glucagon to nonparenchymal cells (mainly endothelial cells and Kupffer cells) isolated from mouse liver was examined by quantitative autoradiography and biochemical methods. Furthermore, the pathway of intracellular transport of colloidal gold-labeled glucagon (AuG) was examined in vivo. Autoradiographic and biochemical results demonstrated many glucagon receptors in both endothelial cells and Kupffer cells, and more receptors being present in endothelial cells than in Kupffer cells. In vivo, endothelial cells internalized AuG particles into coated vesicles via coated pits and transported the particles to endosomes, lysosomes, and abluminal plasma membrane. Therefore, receptor-mediated transcytosis of AuG occurs in endothelial cells. The number of particles present on the abluminal plasma membrane was constant if the amount of injected AuG increased. Therefore, the magnitude of receptor-mediated transcytosis of AuG appears to be regulated by endothelial cells. Kupffer cells internalized the ligand into cytoplasmic tubular structures via plasma membrane invaginations and transported the ligand exclusively to endosomes and lysosomes, suggesting that the ligand is degraded by Kupffer cells.

Junctions between the sinus endothelial cells of rat spleen

1996 ◽  
Vol 287 (1) ◽  
pp. 187-192 ◽  
Author(s):  
Kiyoko Uehara ◽  
Masayuki Miyoshi
Keyword(s):  
Endothelial Cells ◽  
Sinus Endothelial Cells

Localization of ryanodine receptor 3 in the sinus endothelial cells of the rat spleen

2004 ◽  
Vol 317 (2) ◽  
Author(s):  
Kiyoko Uehara ◽  
Hitoshi Onoue ◽  
LoiceH. Jeyakumar ◽  
Sidney Fleischer ◽  
Akira Uehara
Keyword(s):  
Endothelial Cells ◽  
Ryanodine Receptor ◽  
Sinus Endothelial Cells

Application of Backscattered Electron Imaging to the Study of Scavenger Receptor-Mediated Endocytosis by Sinusoidal Cells in Bone Marrow

1985 ◽  
Vol 43 ◽  
pp. 542-545
Author(s):  
R.P. Becker ◽  
J.S. Geoffroy
Keyword(s):  
Bone Marrow ◽  
Endothelial Cells ◽  
Coated Pits ◽  
Thin Sections ◽  
Backscattered Electron Imaging ◽  
Sinusoidal Cells ◽  
Dense Bodies ◽  
Sinusoidal Cell ◽  
Backscattered Electron ◽  
Electron Imaging

The endothelial cells lining the postcapillary venous sinuses (sinusoids) in bone marrow take up colloidal gold-bovine serum albumin (BSA-Au) conjugates by means of a pathway involving coated pits and vesicles. Endocytosis of BSA- Au by these sinusoidal endothelial cells (sinusoidal cells) is rapid. Within one minute of pulse presentation (5 sec; intraaortic injection) with BSA-Au the probe is internalized and processed through pleomorphic endosomes to dense bodies known to be secondary lysosomes. By this time, 17% of the sinusoidal cell related BSA-Au is associated with the surface, while 83% is internalized, of which 2% is present in lysosomes. By four minutes, less than 8% of the observed BSA-Au is not internalized, the bulk being present predominantly in large pleomorphic vacuoles and dense bodies.That the endocytic process involves coated pits and vesicles prompts the suggestion that it may be receptor mediated. In order to investigate this possibility, biochemical and morphological studies were performed to determine the specificity and saturability of the putative receptor. Morphological analysis of TEM thin sections was aided by viewing large areas of the luminal sinusoidal cell surface in secondary electron (SEI) and backscattered electron imaging (BEI) modes of the scanning electron microscope.

scholarly journals Uptake of chemically modified low density lipoproteins in vivo is mediated by specific endothelial cells.

1985 ◽  
Vol 100 (1) ◽  
pp. 103-117 ◽  
Author(s):  
R E Pitas ◽  
J Boyles ◽  
R W Mahley ◽  
D M Bissell
Keyword(s):  
Bone Marrow ◽  
Endothelial Cells ◽  
Kupffer Cells ◽  
Low Density Lipoproteins ◽  
Low Density ◽  
Coated Pits ◽  
Sinusoidal Endothelial Cells ◽  
Modified Lipoproteins

Acetoacetylated (AcAc) and acetylated (Ac) low density lipoproteins (LDL) are rapidly cleared from the plasma (t1/2 approximately equal to 1 min). Because macrophages, Kupffer cells, and to a lesser extent, endothelial cells metabolize these modified lipoproteins in vitro, it was of interest to determine whether endothelial cells or macrophages could be responsible for the in vivo uptake of these lipoproteins. As previously reported, the liver is the predominant site of the uptake of AcAc LDL; however, we have found that the spleen, bone marrow, adrenal, and ovary also participate in this rapid clearance. A histological examination of tissue sections, undertaken after the administration of AcAc LDL or Ac LDL (labeled with either 125I or a fluorescent probe) to rats, dogs, or guinea pigs, was used to identify the specific cells binding and internalizing these lipoproteins in vivo. With both techniques, the sinusoidal endothelial cells of the liver, spleen, bone marrow, and adrenal were labeled. Less labeling was noted in the ovarian endothelia. Uptake of AcAc LDL by endothelial cells of the liver, spleen, and bone marrow was confirmed by transmission electron microscopy. These data suggest uptake through coated pits. Uptake of AcAc LDL was not observed in the endothelia of arteries (including the coronaries and aorta), veins, or capillaries of the heart, testes, kidney, brain, adipose tissue, and duodenum. Kupffer cells accounted for a maximum of 14% of the 125I-labeled AcAc LDL taken up by the liver. Isolated sinusoidal endothelial cells from the rat liver displayed saturable, high affinity binding of AcAc LDL (Kd = 2.5 X 10(-9) M at 4 degrees C), and were shown to degrade AcAc LDL 10 times more effectively than aortic endothelial cells. These data indicate that specific sinusoidal endothelial cells, not the macrophages of the reticuloendothelial system, are primarily responsible for the removal of these modified lipoproteins from the circulation in vivo.

Sign in / Sign up

Export Citation Format

Share Document