Ultrastructure of Spermatogenesis of Syndisyrinx-Punicea (Hickman, 1956) (Platyhelminthes, Rhabdocoela, Umagillidae)

1992 ◽  
Vol 40 (2) ◽  
pp. 153 ◽  
Author(s):  
MM Li ◽  
NA Watson ◽  
K Rohde
Keyword(s):  
Endoplasmic Reticulum ◽  
Multivesicular Bodies ◽  
Dense Bodies ◽  
Cytoplasmic Bridges ◽  
Membrane Bound ◽  
Concentric Circles

Spermatogenesis of Syndisyrinx punicea is described. Spermatogonia are little differentiated, with few organelles and inclusions: polyribosomes, ribosomes, small round mitochondria with few cristae and some endoplasmic reticulum. Primary spermatocytes are large and contain multivesicular bodies that are also found in the cytoplasm of spermatids in greater numbers. Spermatids contain Golgi complexes consisting of a series of concentric circles, and numerous membrane-bound, rod-shaped electron-dense bodies. A zone of differentiation develops with peripheral microtubules, followed by the appearance of a prominent intercentriolar body. Two axonemes grow out in opposite directions from centrioles adjacent and perpendicular to the intercentriolar body. The area of differentiation protrudes and elongates to form the sperm shaft into which the nucleus and mitochondria migrate. Typical rootlets were not observed, although rod-shaped structures situated on each side of the nucleus, seen in one section, may be rudimentary rootlets. Spermatocytes and spermatids are linked by different kinds of cytoplasmic bridges. Spermatogenesis of S. punicea is compared with that in other groups of turbellarians and Neodermata.

scholarly journals FINE STRUCTURE OBSERVATIONS OF THE UPTAKE OF INTRAVENOUSLY INJECTED PEROXIDASE BY THE RAT CHOROID PLEXUS

1967 ◽  
Vol 15 (3) ◽  
pp. 160-165 ◽  
Author(s):  
NORWIN H. BECKER ◽  
ALEX B. NOVIKOFF ◽  
H. M. ZIMMERMAN
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Cerebrospinal Fluid ◽  
Choroid Plexus ◽  
Smooth Endoplasmic Reticulum ◽  
Multivesicular Bodies ◽  
Adult Rats ◽  
Dense Bodies ◽  
Pinocytotic Vesicles ◽  
Membrane Bound

The uptake by the choroid plexus of adult rats of intravenously injected horseradish peroxidase has been investigated by electron microscopy. Within 4 min, the injected protein passes the capillary and is rapidly distributed through extracellular space and choroidal cells. Peroxidase enters the choroidal cells within coated vesicles which act as pinocytotic vesicles. At 15 min, peroxidase activity is present in numerous membrane-bound vesicles, multivesicular bodies, dense bodies and what appear to be segments of smooth endoplasmic reticulum. None of the peroxidase-containing organelles is seen to empty to the ventricular surface. Egress of the extracellular peroxidase into the cerebrospinal fluid is apparently blocked by apical zonulae occludentes between the choroidal cells.

Fine structure of the thraustochytrid Ulkenia amoeboidea. II. The amoeboid stage and formation of zoospores

1982 ◽  
Vol 60 (7) ◽  
pp. 1103-1114 ◽  
Author(s):  
S. Raghu Kumar
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Fine Structure ◽  
Nuclear Division ◽  
Smooth Endoplasmic Reticulum ◽  
Dense Granule ◽  
Multivesicular Bodies ◽  
Golgi Bodies ◽  
Dense Bodies ◽  
Spindle Microtubules

In the thraustochytrid Ulkenia amoeboidea (Bahnweg & Sparrow) Gaertner the contents of the mature vegetative thallus escape from the cell wall in the form of a limax cell. The limax cell is covered by a layer of scales and possesses a nucleus, a paranuclear body, Golgi bodies, mitochondria, bands of smooth endoplasmic reticulum, vacuoles, multivesicular bodies, and cisternae with filamentous contents. The posterior end is filled with smooth endoplasmic reticulum and fusiform vesicles. The anterior end is organelle free and filled with cytoplasm with free ribosomes. Subspherical dense bodies, bounded by a single membrane, are present. The limax cell rounds up prior to mitosis and the Golgi bodies increase in number. During mitosis, the nuclear membrane breaks down totally. Chromosomes are not well defined. Spindle microtubules arise from the centriole and enter the nucleus. After nuclear division, the nuclear envelope is reformed. Cytokinesis is by cleavage into two cells, accompanied by formation of microtubules along the cleavage furrows. The zoospore possesses a nucleus, a paranuclear body, mitochondria, vesicles with presumptive mastigonemes and kinetosome rootlet microtubules and they are covered by a layer of scales. An electron-dense granule and two peripheral thickenings are present within the lumen of the kinetosome.

Localization of various phosphatase activities within the golgi apparatus and lysosomes of rat leydig cells

1986 ◽  
Vol 44 ◽  
pp. 294-295
Author(s):  
M. F. Lalli ◽  
V. Lacroix ◽  
L. Hermo ◽  
Y. Clermont ◽  
C. E. Smith
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Leydig Cells ◽  
Smooth Endoplasmic Reticulum ◽  
Fluid Phase ◽  
Multivesicular Bodies ◽  
Golgi Stack ◽  
Dense Membrane ◽  
Membrane Bound ◽  
Adsorptive Endocytosis

The testosterone-secreting Leydig cells contain an abundance of smooth endoplasmic reticulum, peroxisomes, mitochondria as well as a large, spheroidal, juxtanuclear Golgi apparatus composed of interconnected stacks of saccules (Figs. 1,2). Each Golgi stack appears to be composed of between 5 to 7 saccules or sacculo-tubular elements (Figs.1,2). These cells also possess pale and dense multivesicular bodies and dense membrane-bound bodies identified assecondary lysosomes, all of which have been shown to be involved in fluid phase and adsorptive endocytosis as well as in receptor mediated endocytosis. The purpose of the present study was to characterize the reactivity of Golgi saccules, multivesicular bodies and lysosomes of Leydig cells for different phosphatases.

The ultrastructure of the zoospore of Hyphochytrium catenoides

1985 ◽  
Vol 63 (3) ◽  
pp. 497-505 ◽  
Author(s):  
Elizabeth W. Cooney ◽  
Donald J. S. Barr ◽  
William E. Barstow
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Transition Zone ◽  
Multivesicular Bodies ◽  
Dense Matrix ◽  
Flagellar Membrane ◽  
Membrane Bound

The ultrastructure of the zoospore of Hyphochytrium catenoides Karling is described. The zoospore has a single, anterior, tinsel flagellum. The nucleus is elongate and convoluted with an indentation at the anterior end in which the Golgi cisternae are located. There are large lipid globules in the posterior end of the cell. The ribosomes are loosely enclosed by endoplasmic reticulum, the nuclear envelope, and mitochondria. The mitochondria have tubular cristae in a dense matrix. Microbodies are found appressed to the nuclear envelope and also free in the ribosomal region. Endoplasmic reticulum sheets traverse the ribosome region. The vesiculate cytoplasm has several distinct types of membrane-bound inclusions: (i) multivesicular bodies, (ii) vesicles containing presumptive mastigonemes, (iii) vesicles having an electron-dense cortex with an electron-transparent center, and (iv) electron-opaque vesicles whose contents seem condensed and only partially fill the vesicles. The transition zone from the flagellum to the kinetosome has three segments: a distal set of struts extending from the axonemal doublets into the axoneme core, a midsection of electron-opaque rings, and a distinctive "disclike" terminal plate with a thickened portion between the doublets and the flagellar membrane. The three-part rootlet system has (i) a "ribbed" pair of microtubules on one side of the kinetosome, (ii) a curved "ribbed," single microtubule with electron-opaque backing which originates near the nonfunctional centriole, and (iii) a straight doublet of microtubules without ribs extending from the nonfunctional centriole posteriorly to the midregion of the zoospore.

Ultrastructure of Liver in Lactosyl Ceramidosis

1971 ◽  
Vol 29 ◽  
pp. 312-313
Author(s):  
Z. Hruban ◽  
J. R. Esterly ◽  
G. Dawson ◽  
A. O. Stein
Keyword(s):  
Connective Tissue ◽  
Liver Biopsy ◽  
Osmium Tetroxide ◽  
Close Contact ◽  
Multivesicular Bodies ◽  
Bile Canaliculi ◽  
Dense Bodies ◽  
Marginal Plates ◽  
Membranous Material ◽  
Perichromatin Granules

Samples of a surgical liver biopsy from a patient with lactosyl ceramidosis were fixed in paraformaldehyde and postfixed in osmium tetroxide. Hepatocytes (Figs. 1, 2) contained 0.4 to 2.1 μ inclusions (LCI) limited by a single membrane containing lucid matrix and short segments of curved, lamellated and circular membranous material (Fig. 3). Numerous LCI in large connective tissue cells were up to 11 μ in diameter (Fig. 2). Heterogeneous dense bodies (“lysosomes”) were few and irregularly distributed. Rough cisternae were dilated and contained smooth vesicles and surface invaginations. Close contact with mitochondria was rare. Stacks were small and rare. Vesicular rough reticulum and glycogen rosettes were abundant. Smooth vesicular reticulum was moderately abundant. Mitochondria were round with few cristae and rare matrical granules. Golgi complex was seen rarely (Fig. 1). Microbodies with marginal plates were usual. Multivesicular bodies were very rare. Neutral lipid was rare. Nucleoli were small and perichromatin granules were large. Small bile canaliculi had few microvilli (Fig. 1).

Copper Localization in Cirrhotic Rat Liver by Scanning Electron Microscopy

1969 ◽  
Vol 27 ◽  
pp. 38-39 ◽  
Author(s):  
J. C. Russ ◽  
E. McNatt
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Copper Acetate ◽  
Lead Citrate ◽  
Dense Bodies ◽  
Transmission Electron ◽  
Electron Mode ◽  
Scanning Electron

In order to study the retention of copper in cirrhotic liver, rats were made cirrhotic by carbon tetrachloride inhalation twice weekly for three months and fed 0.2% copper acetate ad libidum in drinking water for one month. The liver tissue was fixed in osmium, sectioned approximately 2000 Å thick, and stained with lead citrate. The section was examined in a scanning electron microscope (JEOLCO JSM-2) in the transmission electron mode.Figure 1 shows a typical area that includes a red blood cell in a sinusoid, a disse, and a portion of the cytoplasm of a hepatocyte which contains several mitochondria, peribiliary dense bodies, glycogen granules, and endoplasmic reticulum.

Analysis of the Anterior Secretory Cells of Onchidohs Muricata (Nudibranchia)

1981 ◽  
Vol 39 ◽  
pp. 614-615
Author(s):  
Roy Skidmore
Keyword(s):  
Endoplasmic Reticulum ◽  
Secretory Granules ◽  
Golgi Body ◽  
The Body ◽  
Secretory Cells ◽  
Secretory Vesicles ◽  
High Magnification ◽  
Large Numbers ◽  
Membrane Bound ◽  
Sole Of The Foot

The long-necked secretory cells in Onchidoris muricata are distributed in the anterior sole of the foot. These cells are interspersed among ciliated columnar and conical cells as well as short-necked secretory gland cells. The long-necked cells contribute a significant amount of mucoid materials to the slime on which the nudibranch travels. The body of these cells is found in the subepidermal tissues. A long process extends across the basal lamina and in between cells of the epidermis to the surface of the foot. The secretory granules travel along the process and their contents are expelled by exocytosis at the foot surface.The contents of the cell body include the nucleus, some endoplasmic reticulum, and an extensive Golgi body with large numbers of secretory vesicles (Fig. 1). The secretory vesicles are membrane bound and contain a fibrillar matrix. At high magnification the similarity of the contents in the Golgi saccules and the secretory vesicles becomes apparent (Fig. 2).

The ultrastructure of the double membrane-bound bodies and endoplasmic reticulum in serial sections of wheat spot mosaic-affected wheat plants

1990 ◽  
Vol 48 (3) ◽  
pp. 694-695
Author(s):  
M. H. Chen ◽  
C. Hiruki
Keyword(s):  
Endoplasmic Reticulum ◽  
High Resolution ◽  
Membrane Structure ◽  
Mosaic Disease ◽  
Serial Sections ◽  
Thin Sections ◽  
Double Membrane ◽  
Southern Alberta ◽  
Membrane Bound ◽  
Scanning Em

Wheat spot mosaic disease was first discovered in southern Alberta, Canada, in 1956. A hitherto unidentified disease-causing agent, transmitted by the eriophyid mite, caused chlorosis, stunting and finally severe necrosis resulting in the death of the affected plants. Double membrane-bound bodies (DMBB), 0.1-0.2 μm in diameter were found to be associated with the disease.Young tissues of leaf and root from 4-wk-old infected wheat plants were fixed, dehydrated, and embedded in Spurr’s resin. Serial sections were collected on slot copper grids and stained. The thin sections were then examined with a Hitachi H-7000 TEM at 75 kV. The membrane structure of the DMBBs was studied by numbering them individually and tracing along the sections to see any physical connection with endoplasmic reticulum (ER) membranes. For high resolution scanning EM, a modification of Tanaka’s method was used. The specimens were examined with a Hitachi Model S-570 SEM in its high resolution mode at 20 kV.

scholarly journals Craniofacial Diseases Caused by Defects in Intracellular Trafficking

Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 726
Author(s):  
Chung-Ling Lu ◽  
Jinoh Kim
Keyword(s):  
Endoplasmic Reticulum ◽  
Membrane Proteins ◽  
Intracellular Trafficking ◽  
Critical Role ◽  
Treatment Strategies ◽  
Soluble Proteins ◽  
Genes Encoding ◽  
Membrane Bound ◽  
Signaling Receptors ◽  
Craniofacial Morphogenesis

Cells use membrane-bound carriers to transport cargo molecules like membrane proteins and soluble proteins, to their destinations. Many signaling receptors and ligands are synthesized in the endoplasmic reticulum and are transported to their destinations through intracellular trafficking pathways. Some of the signaling molecules play a critical role in craniofacial morphogenesis. Not surprisingly, variants in the genes encoding intracellular trafficking machinery can cause craniofacial diseases. Despite the fundamental importance of the trafficking pathways in craniofacial morphogenesis, relatively less emphasis is placed on this topic, thus far. Here, we describe craniofacial diseases caused by lesions in the intracellular trafficking machinery and possible treatment strategies for such diseases.

scholarly journals Widespread occurrence of microRNA-mediated target cleavage on membrane-bound polysomes

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Xiaoyu Yang ◽  
Chenjiang You ◽  
Xufeng Wang ◽  
Lei Gao ◽  
Beixin Mo ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Gene Silencing ◽  
High Frequency ◽  
Small Rnas ◽  
High Throughput Sequencing ◽  
Noncoding Rnas ◽  
Small Interfering Rnas ◽  
Widespread Occurrence ◽  
Membrane Bound ◽  
Different Tissues

Abstract Background Small RNAs (sRNAs) including microRNAs (miRNAs) and small interfering RNAs (siRNAs) serve as core players in gene silencing at transcriptional and post-transcriptional levels in plants, but their subcellular localization has not yet been well studied, thus limiting our mechanistic understanding of sRNA action. Results We investigate the cytoplasmic partitioning of sRNAs and their targets globally in maize (Zea mays, inbred line “B73”) and rice (Oryza sativa, cv. “Nipponbare”) by high-throughput sequencing of polysome-associated sRNAs and 3′ cleavage fragments, and find that both miRNAs and a subset of 21-nucleotide (nt)/22-nt siRNAs are enriched on membrane-bound polysomes (MBPs) relative to total polysomes (TPs) across different tissues. Most of the siRNAs are generated from transposable elements (TEs), and retrotransposons positively contributed to MBP overaccumulation of 22-nt TE-derived siRNAs (TE-siRNAs) as opposed to DNA transposons. Widespread occurrence of miRNA-mediated target cleavage is observed on MBPs, and a large proportion of these cleavage events are MBP-unique. Reproductive 21PHAS (21-nt phasiRNA-generating) and 24PHAS (24-nt phasiRNA-generating) precursors, which were commonly considered as noncoding RNAs, are bound by polysomes, and high-frequency cleavage of 21PHAS precursors by miR2118 and 24PHAS precursors by miR2275 is further detected on MBPs. Reproductive 21-nt phasiRNAs are enriched on MBPs as opposed to TPs, whereas 24-nt phasiRNAs are nearly completely devoid of polysome occupancy. Conclusions MBP overaccumulation is a conserved pattern for cytoplasmic partitioning of sRNAs, and endoplasmic reticulum (ER)-bound ribosomes function as an independent regulatory layer for miRNA-induced gene silencing and reproductive phasiRNA biosynthesis in maize and rice.

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