scholarly journals Fusion of the envelope of mucous droplets with the luminal plasma membrane in acinar cells of the cat submandibular gland.

1976 ◽  
Vol 68 (3) ◽  
pp. 775-781 ◽  
Author(s):  
B Tandler ◽  
J H Poulsen
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Submandibular Gland ◽  
Acinar Cells ◽  
Unit Membrane ◽  
Membrane Unit

The release of mucus from acinar cells of the cat submandibular gland was examined by electron microscopy. The limiting membrane of mucous droplets fuses with the luminal plasma membrane to form a five-layered contact. This is converted to a three-layered membrane (unit membrane) by avulsion of the plasmalemma. Attenuation and rupture of this membranous barrier permits the contents of the mucous droplets to flow into the lumen.

scholarly journals ON THE THICKNESS OF THE UNIT MEMBRANE

1963 ◽  
Vol 17 (2) ◽  
pp. 413-421 ◽  
Author(s):  
Toshiyuki Yamamoto
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Electron Micrographs ◽  
Synaptic Vesicles ◽  
Multivesicular Bodies ◽  
Unit Membrane ◽  
Cell Organelles ◽  
Membrane Unit ◽  
Nuclear Membranes ◽  
Golgi Vesicles

Peak-to-peak distances between two dense lines of the unit membranes of cell organelles were measured on electron micrographs. These distances were compared with corresponding measurements on the plasma membrane and assigned a percentage value. The comparison between organelle and plasma membrane was always carried out with the same negative, in order to exclude as far as possible errors due to differences in focus or other causes. It was revealed by this study that the membranous structures of the cell can be classified into two groups, one thicker and one thinner. Unit membranes of the thicker group (synaptic vesicles, vesicles and capsules of multivesicular bodies, Golgi vesicles) were not significantly different in thickness from the plasma membrane. Unit membranes of the thinner group (mitochondria, nuclear membranes, Golgi lamellae, endoplasmic reticulum), however, were between 85 and 90 per cent of the thickness of the plasma membrane.

The Effect of Chronic Isoproterenol Administration on the Plasma Membrane of Acinar Cells in Rat Submandibular Gland

1984 ◽  
Vol 63 (8) ◽  
pp. 1028-1031
Author(s):  
N. Sahara ◽  
N. Araki ◽  
K. Fukasawa ◽  
M. Harada ◽  
K. Suzuki
Keyword(s):  
Plasma Membrane ◽  
Submandibular Gland ◽  
Acinar Cells ◽  
Rat Submandibular Gland

The Mechanism of Watery Vacuolation in the Acinar Cells of the Submandibular Gland

1969 ◽  
Vol 4 (1) ◽  
pp. 55-70
Author(s):  
R. L. TAPP
Keyword(s):  
Electron Microscopy ◽  
Oxidative Phosphorylation ◽  
Propylene Glycol ◽  
Submandibular Gland ◽  
Light And Electron Microscopy ◽  
Acinar Cells ◽  
Basic Solution ◽  
External Fluid ◽  
Rat Submandibular Gland

Watery vacuolation was induced in the acinar cells of the rat submandibular gland by allowing small pieces of tissue (2 mm3 to stand in suitable unoxygenated fluids at 20°C, and cells in various stages of vacuolation were examined by light and electron microscopy. No structural evidence for pinocytosis was found. Using basic solution (NaCl, 8.0 g/l.; CaCl2 0.2 g/l.; NaHCO3 1.0 g/l.) it was confirmed that vacuolation does not occur at 0°C, and that it is greatly reduced if Ca2+ is omitted. Vacuoles develop in pieces of tissue which have been separated from the animal for up to 2 h, provided that the pieces are then immersed in a suitable fluid. Vacuolation can occur in the absence of external Na+ or Cl-: cations substituted for Na+ allowed vacuolation in the order: Li+, full; Cs+, slight; K+ and Rb+, none. It can be prevented, however, if sufficient sucrose (> 210 m-osmoles) or glucose is added to the external fluid, but not by the same quantities of urea, glycerol, or propylene glycol. Metabolic poisons which block oxidative phosphorylation or glycolysis do not prevent vacuolation. It is concluded that vacuolation does not involve pinocytosis but represents the secondary segregation of fluid from an oedematous cytoplasm. The mechanism of secondary segregation and its possible relationship to secretion are discussed.

scholarly journals Histochemical and cytochemical localization of (Na+-K+)-activated adenosine triphosphatase in the acini of dog submandibular glands.

1978 ◽  
Vol 26 (10) ◽  
pp. 835-845 ◽  
Author(s):  
I Nakagaki ◽  
T Goto ◽  
S Sasaki ◽  
Y Imai
Keyword(s):  
Plasma Membrane ◽  
Light Microscopy ◽  
Submandibular Gland ◽  
Adenosine Triphosphatase ◽  
Acinar Cells ◽  
Mucous Cells ◽  
Reaction Products ◽  
Cytochemical Localization ◽  
Atpase Reaction ◽  
Fresh Frozen

p-Nitrophenyl phosphatase (p-NPPase) activity of (Na+-K+)-activated adenosine triphosphatase ((Na+-K+)-ATPase) on the acinar cells of dog submandibular gland was demonstrated by using light microscopy. The reaction products of p-NPPase of fresh frozen sections were seen to be localized on the basal parts of acini, and disappeared when the sections were incubated in medium containing 10(-3) Mouabain or in a K-free medium. Under the electron microscope, the reaction products of ATPase were found to be localized on the basolateral plasma membrane of both serous and mucous cells. On the microvilli of the luminal plasma membrane of the acinar cell, a small quantity of the reaction products was also present. This localization of ATPase reaction products on the serous and mucous cells seemed to coincide well with that of p-NPPase activity observed on the acini under light microscopy. Possible explanations are given regarding distribution of the above mentioned enzymes in relation to the cation transport of the plasma membrane. Structural and functional asymmetrical properties of acinar cells of the dog submandibular gland are also discussed.

Electron microscopy of endocardial cell populations

1978 ◽  
Vol 36 (2) ◽  
pp. 486-487
Author(s):  
T. G. Sarphie ◽  
C. R. Comer ◽  
D. J. Allen
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Cellular Transformation ◽  
Cell Populations ◽  
Cell Surfaces ◽  
Kb Cells ◽  
Dna Viruses ◽  
Cell Cycles ◽  
Ultrastructural Studies ◽  
Endocardial Cell

Previous ultrastructural studies have characterized surface morphology during norma cell cycles in an attempt to associate specific changes with specific metabolic processes occurring within the cell. It is now known that during the synthetic ("S") stage of the cycle, when DNA and other nuclear components are synthesized, a cel undergoes a doubling in volume that is accompanied by an increase in surface area whereby its plasma membrane is elaborated into a variety of processes originally referred to as microvilli. In addition, changes in the normal distribution of glycoproteins and polysaccharides derived from cell surfaces have been reported as depreciating after cellular transformation by RNA or DNA viruses and have been associated with the state of growth, irregardless of the rate of proliferation. More specifically, examination of the surface carbohydrate content of synchronous KB cells were shown to be markedly reduced as the cell population approached division Comparison of hamster kidney fibroblasts inhibited by vinblastin sulfate while in metaphase with those not in metaphase demonstrated an appreciable decrease in surface carbohydrate in the former.

Triple Fixation For Electron Microscopy

1968 ◽  
Vol 26 ◽  
pp. 90-91 ◽  
Author(s):  
M. A. Hayat
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Electron Beam ◽  
Plasma Membrane ◽  
Myelin Sheath ◽  
Good Deal ◽  
Granular Structure ◽  
Oxidizing Agent ◽  
Fixation Technique ◽  
Large Clusters

Potassium permanganate has been successfully employed to study membranous structures such as endoplasmic reticulum, Golgi, plastids, plasma membrane and myelin sheath. Since KMnO4 is a strong oxidizing agent, deposition of manganese or its oxides account for some of the observed contrast in the lipoprotein membranes, but a good deal of it is due to the removal of background proteins either by dehydration agents or by volatalization under the electron beam. Tissues fixed with KMnO4 exhibit somewhat granular structure because of the deposition of large clusters of stain molecules. The gross arrangement of membranes can also be modified. Since the aim of a good fixation technique is to preserve satisfactorily the cell as a whole and not the best preservation of only a small part of it, a combination of a mixture of glutaraldehyde and acrolein to obtain general preservation and KMnO4 to enhance contrast was employed to fix plant embryos, green algae and fungi.

scholarly journals Redistribution of a rab3-like GTP-binding protein from secretory granules to the Golgi complex in pancreatic acinar cells during regulated exocytosis

1994 ◽  
Vol 124 (1) ◽  
pp. 43-53 ◽  
Author(s):  
BP Jena ◽  
FD Gumkowski ◽  
EM Konieczko ◽  
GF von Mollard ◽  
R Jahn ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Golgi Complex ◽  
Binding Protein ◽  
Secretory Granules ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Apical Plasma Membrane ◽  
Gtp Binding Protein ◽  
Regulated Exocytosis ◽  
Gtp Binding

Regulated secretion from pancreatic acinar cells occurs by exocytosis of zymogen granules (ZG) at the apical plasmalemma. ZGs originate from the TGN and undergo prolonged maturation and condensation. After exocytosis, the zymogen granule membrane (ZGM) is retrieved from the plasma membrane and ultimately reaches the TGN. In this study, we analyzed the fate of a low M(r) GTP-binding protein during induced exocytosis and membrane retrieval using immunoblots as well as light and electron microscopic immunocytochemistry. This 27-kD protein, identified by a monoclonal antibody that recognizes rab3A and B, may be a novel rab3 isoform. In resting acinar cells, the rab3-like protein was detected primarily on the cytoplasmic face of ZGs, with little labeling of the Golgi complex and no significant labeling of the apical plasmalemma or any other intracellular membranes. Stimulation of pancreatic lobules in vitro by carbamylcholine for 15 min, resulted in massive exocytosis that led to a near doubling of the area of the apical plasma membrane. However, no relocation of the rab3-like protein to the apical plasmalemma was seen. After 3 h of induced exocytosis, during which time approximately 90% of the ZGs is released, the rab3-like protein appeared to translocate to small vesicles and newly forming secretory granules in the TGN. No significant increase of the rab3-like protein was found in the cytosolic fraction at any time during stimulation. Since the protein is not detected on the apical plasmalemma after stimulation, we conclude that recycling may involve a membrane dissociation-association cycle that accompanies regulated exocytosis.

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