Fine structure of granulated cells in the posterior cardinal and renal veins of Amia calva L.

1976 ◽  
Vol 54 (6) ◽  
pp. 843-851 ◽  
Author(s):  
John H. Youson
Keyword(s):  
Fine Structure ◽  
Secretory Granules ◽  
Immediate Release ◽  
Nerve Terminals ◽  
Renal Veins ◽  
Subendothelial Space ◽  
Secretory Products ◽  
Amia Calva ◽  
Relationship Of ◽  
The Relationship

Granulated cells located in the walls of the posterior cardinal and renal veins in the holostean fish Amia calva resemble cells of the adrenal medulla of higher vertebrates. The cells all contain similar electron-dense secretory granules, apparently originating from the Golgi apparatus, and are innervated by nerve terminals. These features suggest that the cells are involved in the production and release of catecholamines. The relationship of the cells to the endothelium of the large veins also suggests that the secretory products of the cells reach the circulation by traversing a complex subendothelial space and passing through the fenestrae of the endothelium. This appears to be an efficient means for the immediate release and distribution of catecholamines in this species of fish.

scholarly journals DNA AND THE FINE STRUCTURE OF SYNAPTIC CHROMOSOMES IN THE DOMESTIC ROOSTER (GALLUS DOMESTICUS)

1964 ◽  
Vol 23 (1) ◽  
pp. 63-78 ◽  
Author(s):  
James R. Coleman ◽  
Montrose J. Moses
Keyword(s):  
Electron Microscopy ◽  
Heavy Metal ◽  
Fine Structure ◽  
Electron Microscope ◽  
Meiotic Prophase ◽  
Gallus Domesticus ◽  
Feulgen Staining ◽  
Synaptinemal Complex ◽  
Relationship Of ◽  
The Relationship

The indium trichloride method of Watson and Aldridge (38) for staining nucleic acids for electron microscopy was employed to study the relationship of DNA to the structure of the synaptinemal complex in meiotic prophase chromosomes of the domestic rooster. The selectivity of the method was demonstrated in untreated and DNase-digested testis material by comparing the distribution of indium staining in the electron microscope to Feulgen staining and ultraviolet absorption in thicker sections seen with the light microscope. Following staining by indium, DNA was found mainly in the microfibril component of the synaptinemal complex. When DNA was known to have been removed from aldehyde-fixed material by digestion with DNase, indium stainability was also lost. However, staining of the digested material with non-selective heavy metal techniques demonstrated the presence of material other than DNA in the microfibrils and showed that little alteration in appearance of the chromosome resulted from DNA removal. The two dense lateral axial elements of the synaptinemal complex, but not the central one to any extent, also contained DNA, together with non-DNA material.

scholarly journals FLIM-based pH measurements reveal incretin-induced rejuvenation of aged insulin secretory granules

2017 ◽  
Author(s):  
Martin Neukam ◽  
Anke Sönmez ◽  
Michele Solimena
Keyword(s):  
Secretory Granules ◽  
Population Level ◽  
Underlying Mechanism ◽  
Fusion Pore ◽  
Fluorescence Lifetime Imaging ◽  
Lifetime Imaging ◽  
Luminal Ph ◽  
Relationship Of ◽  
First Time ◽  
The Relationship

AbstractInsulin is stored in dense-core secretory granules (SGs) and is released from beta cells in two distinct phases upon glucose stimulation. Newly synthesized insulin SGs are secreted preferentially, but the underlying mechanism of this phenomenon remains elusive. The relationship of SG age with their intraluminal pH is of particular interest: proinsulin conversion by prohormone convertases follows the acidification of immature SGs by the vacuolar proton-translocating ATPase (v-ATPase). v-ATPases may also participate in the formation of the fusion pore for SG exocytosis, with intraluminal alkalinization inhibiting membrane fusion. Previous studies examined the luminal pH of SGs on a population level only. Here we measured the pH-dependent lifetime changes of eCFP fused to the ICA512-RESP18 homology domain to assess for the first time the luminal pH of individual age-defined SGs in insulinoma INS-1 cells by fluorescence-lifetime imaging microscopy. We show that 2-4-hour-old young SGs have a pH of ~5.5, while 26-28-hour-old SGs have a pH of ~6.2. Remarkably, the GLP-1 receptor agonist Exendin-4 prompted the re-acidification of old SGs in a glutamate-dependent fashion, while it did not affect the pH of young SGs. This study demonstrates that insulin SGs change their pH over time - a change that is reversible by insulin secretagogues. Hence, it provides novel insight into the mechanisms accounting for aging and exocytosis of SGs and suggests that their ‘rejuvenation’ may be exploited to enhance insulin secretion in diabetes.

scholarly journals Effects of Hypertonic Stress on The Fine Structure of Sickled Erythrocytes

Blood ◽  
1970 ◽  
Vol 35 (4) ◽  
pp. 437-446 ◽  
Author(s):  
JAMES G. WHITE
Keyword(s):  
Fine Structure ◽  
Cell Membrane ◽  
Characteristic Feature ◽  
Dominant Factor ◽  
Hypertonic Stress ◽  
Erythrocyte Sickling ◽  
Relationship Of ◽  
The Relationship

Abstract The tendency of polymers of sickled hemoglobin (HbS) to align parallel and equidistant to each other has been pointed out in many investigations, and is considered a characteristic feature of erythrocyte sickling. A previous study on stroma-free solutions of sickled hemoglobin, however, suggested that polymers of HbS preferentially assumed radial rather than parallel relationships. Sickled erythrocytes were exposed to hypertonic stress in the present study in order to observe whether parallel bundles of polymers remained intact after removal of the cell membrane. Bundles of polymers in salicylate damaged sickled cells regularly developed branching and radial configurations similar to those found in stroma-free gels. Rotational stress appears to be the dominant factor influencing the relationship of HbS polymers, and the force generated by that tension may be an important factor in erythrocyte sickling.

The Influence of Fixation Upon the Fine Structure of The Z-Disk of Rat Striated Muscle

1970 ◽  
Vol 6 (1) ◽  
pp. 257-276
Author(s):  
D. N. LANDON
Keyword(s):  
Fine Structure ◽  
Osmium Tetroxide ◽  
Striated Muscle ◽  
Square Lattice ◽  
Cross Linking ◽  
Functional Implications ◽  
The Cross ◽  
Relationship Of ◽  
The Relationship ◽  
Lattice Pattern

The fine structure of the Z-disk in rat striated muscle has been found to be dependent upon the manner of its fixation. Material primarily fixed in osmium tetroxide shows a square or ‘woven’ lattice in transverse sections, with a spacing of around 22 nm, and with its axes off-set by 45° from the axes of alignment of the files of I-filaments prior to their entry into the Z-disk. In longitudinal sections the disk may have a zig-zag appearance with individual I-filaments of one sarcomere apparently linked obliquely to 2 or more I-filaments of the next. Transverse sections of Z-disks in muscle primarily fixed in glutaraldehyde show a square-lattice pattern with a spacing of about II nm, its axes coinciding with the axes of alignment of the adjacent I-filaments. In longitudinal sections oblique linkages of the ends of the I-filaments are not seen, and they appear either to interdigitate, or to be longitudinally continuous with those of the next sarcomere. This second fine structure is interpreted as being the consequence of the superimposition of 2 basic square lattices, each of 22-nm period, 50 % out of register along each axis, and each fort-ned from the lateral linkage of the ends of the interdigitating I-filaments with the ends of adjacent filaments from their own sarcomere. The relationship of this postulated structure to the lattice patterns previously described, the nature of the cross-linking material, and some possible functional implications are briefly discussed.

The flagellar apparatus in zoospores of Phytophthora, Pythium, and Halophytophthora

1992 ◽  
Vol 70 (11) ◽  
pp. 2163-2169 ◽  
Author(s):  
D. J. S. Barr ◽  
N. L. Désaulniers
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Flagellar Apparatus ◽  
Posterior Root ◽  
Transmission Electron ◽  
Structure Morphology ◽  
Cytoplasmic Microtubules ◽  
Relationship Of ◽  
The Relationship

The flagellar apparatuses of 14 species of Phytophthora, 2 of Halophytophthora, and 4 of Pythium are compared in the transmission electron microscope. Except for Phytophthora infestans and Phytophthora mirabilis there were no significant differences in fine structure morphology. There are six flagellar roots: a ribbed triplet consisting of three main microtubules and secondary microtubules; an anterior doublet; a multistranded, band-shaped root of five to nine microtubules; a posterior root of two to four microtubules; and roots consisting of arrays of cytoplasmic microtubules and nuclear-associated microtubules. In P. infestans and P. mirabilis the multistranded root is missing, the posterior root contains five or six microtubules, and the anterior ribbed root contains four main microtubules. The transitional zones in all species are similar. The relationship of the Pythiaceae with other Oomycetes is discussed. Key words: taxonomy, phytogeny, cytology, Oomycetes, Pythiaceae.

Acid Phosphatase Activity in Mammalian Parathyroid Glands

1971 ◽  
Vol 29 ◽  
pp. 516-517
Author(s):  
W. Allen Shannon ◽  
Sanford I. Roth
Keyword(s):  
Enzymatic Activity ◽  
Cell Membranes ◽  
Secretory Granules ◽  
Basement Membranes ◽  
Parathyroid Glands ◽  
Capillary Endothelium ◽  
Golgi Membranes ◽  
Parenchymal Cells ◽  
Relationship Of ◽  
The Relationship

It has been suggested that the parathyroid secretory granules might represent lysosomes. Since lysosomes are known to contain acid phosphatases (AcPase), this enzymatic activity was investigated with a modified Gomori lead method with β-glycerophosphate as the substrate to determine the relationship of secretory granules to lysosomes in adenomatous and hyperplastic (primary chief cell type) human, and normal bovine, human, and rat parathyroid glands.Intracellular activity was demonstrated in the lipofuchsin granules and in rare, membrane-limited bodies consistent with lysosomes (Figs. 1 and 2). These lysosomal granules were often irregular in shape and 450 to 850 mμ in diameter. Lead precipitate was also observed in association with some Golgi membranes and cisternae and in a few small Golgi vesicles (Fig.3). There was strong AcPase reactivity in the lumenal cell membranes of the capillary endothelium (Fig. 4) though the cell membranes adjacent to the basement membranes and those of the parathyroid parenchymal cells were devoid of enzymatic activity. No activity was present in the numerous small secretory granules or in the granular endoplasmic reticulum (Figs. 1 and 2).

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