Fine structure of endothelial cells of vertebrates. Distribution of dense granules

1970 ◽  
Vol 131 (2) ◽  
pp. 148-155 ◽  
Author(s):  
R. C. Santolaya ◽  
F. Bertini
Keyword(s):  
Endothelial Cells ◽  
Fine Structure ◽  
Dense Granules

Small GTP-binding Protein RalA Associates with Weibel-Palade Bodies in Endothelial Cells

1999 ◽  
Vol 82 (09) ◽  
pp. 1177-1181 ◽  
Author(s):  
Hubert de Leeuw ◽  
Pauline Wijers-Koster ◽  
Jan van Mourik ◽  
Jan Voorberg
Keyword(s):  
Endothelial Cells ◽  
Binding Proteins ◽  
Binding Protein ◽  
Control Release ◽  
Small Gtpase ◽  
Gtp Binding Protein ◽  
Two Dimensional Gel Electrophoresis ◽  
Gtp Binding Proteins ◽  
Dense Granules ◽  
Gtp Binding

SummaryIn endothelial cells von Willebrand factor (vWF) and P-selectin are stored in dense granules, so-called Weibel-Palade bodies. Upon stimulation of endothelial cells with a variety of agents including thrombin, these organelles fuse with the plasma membrane and release their content. Small GTP-binding proteins have been shown to control release from intracellular storage pools in a number of cells. In this study we have investigated whether small GTP-binding proteins are associated with Weibel-Palade bodies. We isolated Weibel-Palade bodies by centrifugation on two consecutive density gradients of Percoll. The dense fraction in which these subcellular organelles were highly enriched, was analysed by SDS-PAGE followed by GTP overlay. A distinct band with an apparent molecular weight of 28,000 was observed. Two-dimensional gel electrophoresis followed by GTP overlay revealed the presence of a single small GTP-binding protein with an isoelectric point of 7.1. A monoclonal antibody directed against RalA showed reactivity with the small GTP-binding protein present in subcellular fractions that contain Weibel-Palade bodies. The small GTPase RalA was previously identified on dense granules of platelets and on synaptic vesicles in nerve terminals. Our observations suggest that RalA serves a role in regulated exocytosis of Weibel-Palade bodies in endothelial cells.

scholarly journals Structure of the Rete Mirabile in the Kidney of the Rat as Seen with the Electron Microscope

1960 ◽  
Vol 7 (1) ◽  
pp. 103-106 ◽  
Author(s):  
J. B. Longley ◽  
W. G. Banfield ◽  
D. C. Brindley
Keyword(s):  
Endothelial Cells ◽  
Fine Structure ◽  
Electron Microscope ◽  
Electron Micrographs ◽  
Simple Diffusion ◽  
Functional Capabilities ◽  
Rete Mirabile ◽  
Peritubular Capillaries ◽  
Fenestrated Endothelium

Electron micrographs of the rete mirabile in the medulla of the rat have revealed that the endothelium of the afferent and efferent vessels are markedly different in fine structure. The venous capillaries returning blood from the papilla are lined with a fenestrated endothelium much like that in the peritubular capillaries of the kidney. The arterial capillaries delivering blood to the papilla have an unperforated lining of overlapping endothelial cells with extremely irregular tapered margins. It is pointed out that the organization of particularly the latter vessels suggests that the functional capabilities of these retia go beyond those of a simple diffusion countercurrent exchanger.

The fine structure of Verson's glands in molting larvae of Calpodes ethlius (Hesperiidae, Lepidoptera)

1973 ◽  
Vol 51 (11) ◽  
pp. 1201-1210 ◽  
Author(s):  
Joan Lai-Fook
Keyword(s):  
Fine Structure ◽  
Secretory Cell ◽  
Duct Cell ◽  
Secretory Cells ◽  
Dense Granules ◽  
Cell Processes ◽  
Residual Bodies

The three cells which make up Verson's glands in Calpodes undergo drastic changes as they produce the cuticular linings and the secretions of the glands. The duct cell secretes only the typical cuticular duct. The saccule cell produces both the atypical cuticular saccule and dense granules which are discharged just before ecdysis. The secretory cell is much enlarged by vacuoles which remain separate until they too are discharged before ecdysis. Dense granules are also produced by the secretory cell. During deposition of the cuticular duct and saccule, their lumina arc packed with cell processes containing microtubules, which appear to arise from centrioles. Isolation and residual bodies appear in both the saccule and secretory cells even before discharge of their secretions.

Adenosine Nucleotides and Serotonin Stimulate von Wille-brand Factor Release from Cultured Human Endothelial Cells

1994 ◽  
Vol 72 (01) ◽  
pp. 132-139 ◽  
Author(s):  
D S Palmer ◽  
M T Aye ◽  
P R Ganz ◽  
M Halpenny ◽  
S Hashemi
Keyword(s):  
Endothelial Cells ◽  
Adenine Nucleotides ◽  
Maximal Response ◽  
Dependent Manner ◽  
Dense Granules ◽  
Primary Hemostasis ◽  
Activated Platelets ◽  
Von Willebrand

SummaryEndothelial cells (ECs) synthesize and release von Willebrand factor (vWf) either constitutively or from Weibel-Palade bodies by a regulated pathway. Although stimulated release of vWf from ECs occurs following exposure to thrombin, histamine, interleukin, tissue necrosis factor and fibrin in vitro, these agents are unlikely to be present in physiologically relevant concentrations during the initial stages of primary hemostasis. Alternatively, agents known to be released from the dense granules of activated platelets at the sites of vascular injury may provide the initial physiological stimuli for vWf release from ECs in vivo. We have examined the effects of the platelet secretagogues ADP, AMP, ATP and serotonin on the release of vWf from ECs and demonstrated enhanced release in all cases. The extent and time at which optimum vWf release was observed depended on the agonist and its concentration. At 3 nM, optimum release occurred after 4 hours with ADP (330 %/ml) or 1 h with AMP (153%/ml) or ATP (450%/ml). At 30 nM, optimum release was seen after 1 hour with ADP (315 %/ml) or AMP (595%/ml) and after 15 min with ATP (938%/ml). With serotonin, optimal release was seen by 30 min at 0.3 μM (1034%/ml) and after 1 h at 1 pM (745%/ml) although the response after 15 min was nearly equivalent (667%/ml). The doses giving 50% of maximal response (ED50) after 1 h were 6.5 nM (ADP), 15.2 nM (AMP) and 2.4 nM (ATP) and 20 nM for ATP or 75 nM for serotonin after 15 or 30 min respectively. ADP also enhanced PGI2 release from ECs in a dose- and time-dependent manner. These observations support a mechanism whereby activated platelets, which interact with and bind to ECs or subendothelium and release adenine nucleotides or serotonin from platelet dense granules, could stimulate the release of vWf from adjacent ECs thereby enhancing EC-platelet interactions and facilitating primary hemostasis.

scholarly journals OBSERVATIONS ON THE FINE STRUCTURE OF LUTEIN CELLS

1962 ◽  
Vol 12 (1) ◽  
pp. 101-113 ◽  
Author(s):  
Allen C. Enders
Keyword(s):  
Electron Microscopy ◽  
Endothelial Cells ◽  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Steroid Hormones ◽  
Osmium Tetroxide ◽  
Secretory Activity ◽  
Corpora Lutea ◽  
Pericapillary Space ◽  
Lutein Cell

Corpora lutea from the period of delayed implantation and from early postimplantation stages of the armadillo, mink, and rat were fixed in buffered osmium tetroxide-sucrose or potassium permanganate. After rapid dehydration, the portions of the corpora lutea were embedded in either methacrylate or epoxy resin. Examination of the lutein cells by electron microscopy revealed the presence, in the better preserved material, of an extensive development of tubular agranular endoplasmic reticulum. Although the membranes of the endoplasmic reticulum are the most striking feature of the lutein cells of both stages of the three animals examined, very numerous large mitochondria with cristae that exhibit a variety of forms tending toward villiform, and protrusions and foldings of the lutein cell margins on the pericapillary space are also characteristic of these cells. Certain minor differences in the lutein cells of the species examined are also noted. No indications of conversion of mitochondria into lipid, of accumulation of lipid in the Golgi area, or of the protrusion of lutein cells into spaces between the endothelial cells, as suggested by other authors, were noted in these preparations. Some of the difficulties inherent in the visualization of the secretory activity of cells producing steroid hormones are briefly discussed.

scholarly journals VWF maturation and release are controlled by 2 regulators of Weibel-Palade body biogenesis: exocyst and BLOC-2

Blood ◽  
2020 ◽  
Vol 136 (24) ◽  
pp. 2824-2837 ◽  
Author(s):  
Anish V. Sharda ◽  
Alexandra M. Barr ◽  
Joshua A. Harrison ◽  
Adrian R. Wilkie ◽  
Chao Fang ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Endothelial Cells ◽  
Interacting Proteins ◽  
Binding Partner ◽  
Dense Granules ◽  
Exocyst Complex ◽  
Molecule Inhibitor ◽  
Lysosome Related Organelles ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract von Willebrand factor (VWF) is an essential hemostatic protein that is synthesized in endothelial cells and stored in Weibel-Palade bodies (WPBs). Understanding the mechanisms underlying WPB biogenesis and exocytosis could enable therapeutic modulation of endogenous VWF, yet optimal targets for modulating VWF release have not been established. Because biogenesis of lysosomal related organelle-2 (BLOC-2) functions in the biogenesis of platelet dense granules and melanosomes, which like WPBs are lysosome-related organelles, we hypothesized that BLOC-2–dependent endolysosomal trafficking is essential for WPB biogenesis and sought to identify BLOC-2–interacting proteins. Depletion of BLOC-2 caused misdirection of cargo-carrying transport tubules from endosomes, resulting in immature WPBs that lack endosomal input. Immunoprecipitation of BLOC-2 identified the exocyst complex as a binding partner. Depletion of the exocyst complex phenocopied BLOC-2 depletion, resulting in immature WPBs. Furthermore, releasates of immature WPBs from either BLOC-2 or exocyst-depleted endothelial cells lacked high-molecular weight (HMW) forms of VWF, demonstrating the importance of BLOC-2/exocyst-mediated endosomal input during VWF maturation. However, BLOC-2 and exocyst showed very different effects on VWF release. Although BLOC-2 depletion impaired exocytosis, exocyst depletion augmented WPB exocytosis, indicating that it acts as a clamp. Exposure of endothelial cells to a small molecule inhibitor of exocyst, Endosidin2, reversibly augmented secretion of mature WPBs containing HMW forms of VWF. These studies show that, although BLOC-2 and exocyst cooperate in WPB formation, only exocyst serves to clamp WPB release. Exocyst function in VWF maturation and release are separable, a feature that can be exploited to enhance VWF release.

Seasonal Changes in the Fine Structure of the Basal Granular Cells of the Bat Thyroid

1967 ◽  
Vol 2 (3) ◽  
pp. 401-410
Author(s):  
E. A. NUNEZ ◽  
R. P. GOULD ◽  
D. W. HAMILTON ◽  
J. S. HAYWARD ◽  
S. J. HOLT
Keyword(s):  
Fine Structure ◽  
Seasonal Changes ◽  
Follicular Epithelium ◽  
Thyroid Cell ◽  
Basal Region ◽  
Basal Cells ◽  
Uniform Size ◽  
Thyroid Cells ◽  
Cytoplasmic Matrix ◽  
Dense Granules

The fine structure of the thyroid gland of non-hibernating, hibernating, and intermittently aroused hibernating bats was examined. It was found that in addition to the ordinary follicular cell, another widespread thyroid cell type is present in all bats examined. This cell is situated in the basal region of the thyroid follicle and is characterized by a cytoplasm full of secretory-like granules. In the basal cells of bats captured in April and June the granules consist of an extremely dense core and are of a uniform size averaging from 0.1-0.5 µ in diameter. In bats caught in August the solid dense granules vary greatly in size and large granules of diameters from 2 to 5 µ are common. These large granules are often found concentrated in groups in the most basal region of the follicular epithelium. Hibernating bats are characterized by partly or totally degranulated basal thyroid cells. The cytoplasmic granules in the partly degranulated cell vary greatly in appearance, ranging from solid dense granules to empty vesicles. In totally degranulated basal cells, empty vesicles fill the cytoplasmic matrix. The granular endoplasmic reticulum of the basal thyroid cell also shows seasonal changes, while the Golgi complex remains a well-developed organelle throughout the year. These observations suggest that the thyroid basal granular cell is involved in secretory activities; its possible functional role is discussed.

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