The Structure and Function of the So-Called Yolk-Nucleus in the Oogenesis of Birds

1962 ◽  
Vol s3-103 (64) ◽  
pp. 411-415
Author(s):  
SARDUL S. GURAYA
Keyword(s):  
Structure And Function ◽  
Lipid Bodies ◽  
Cytoplasmic Inclusions ◽  
Histochemical Tests ◽  
Spherical Mass ◽  
And Function ◽  
Yolk Nucleus

The so-called yolk-nucleus of the young oocytes of birds is situated close to the nucleus. It is a homogeneous, spherical mass with radiating projections. Histochemical tests show it to be rich in RNA. Lipid bodies of diverse nature and mitochondria are aggregated in its vicinity. The yolk-nucleus disintegrates as the yolk-bodies are formed, and meanwhile the cytoplasmic inclusions that had aggregated round it seem to disperse and disappear. When the yolk-bodies have been fully formed, the yolk-nucleus is reconstituted once more as a homogeneous, spherical mass.

The structure and function of the adhesive organ in strigeid trematodes

Parasitology ◽  
1966 ◽  
Vol 56 (2) ◽  
pp. 209-226 ◽  
Author(s):  
Christina Öhman
Keyword(s):  
Life Cycle ◽  
Leucine Aminopeptidase ◽  
Structure And Function ◽  
The Body ◽  
Adhesive Organ ◽  
Enzyme Formation ◽  
Histochemical Tests ◽  
Mode Of Attachment ◽  
And Function ◽  
Small Activity

The biology and life cycle of Apatemon gracilis minor is briefly described.The morphology of the cup–shaped forebody with the small lappets, the pear-shaped subcuticular cells and the very flexible finger–like adhesive organ lobes is considered in some detail.An extensive description of the body musculature is given and the mode of attachment of the parasite to the host mucosa is studied.The main results of the histochemical tests are: (a) a relative absence of enzymes in the adhesive organ and a greater activity in the lappets; (b) the presence of two types of esterase, a non-specific esterase of B-type in the caecal cells and a non-specific esterase of resistant type, possibly a non-specific cholinesterase, in the rest of the reacting sites in the parasite; (c) a relatively small activity for leucine aminopeptidase; (d) the presence of RNA at all sites of enzyme formation; and finally, (e), the presence of enzymes and carbohydrates in the cuticle.The activities of the parasite result in a local disruption of the host intestinal mucosa at the site of attachment. It is suggested that this is a result of the activities of the enzymes secreted by the parasite.The absorption of nutrients and the circulatory function of the excretory system are discussed.I should like to express my sincere thanks to Dr D. A. Erasmus for helpful discussions and advice during the progress of the work and to Professor J. Brough for giving me the opportunity to work in his department. The study was conducted during the tenure of a grant from Svenska Vetenskapliga Centralrådet i Finland.

Structure and function of neural networks in the retina

1988 ◽  
Vol 46 ◽  
pp. 26-27
Author(s):  
Peter Sterling
Keyword(s):  
Ganglion Cells ◽  
Three Dimensional ◽  
Structure And Function ◽  
Synaptic Connections ◽  
Visual Axis ◽  
One Dimensional ◽  
Cat Retina ◽  
Ultrathin Sections ◽  
And Function ◽  
Insight Into

The synaptic connections in cat retina that link photoreceptors to ganglion cells have been analyzed quantitatively. Our approach has been to prepare serial, ultrathin sections and photograph en montage at low magnification (˜2000X) in the electron microscope. Six series, 100-300 sections long, have been prepared over the last decade. They derive from different cats but always from the same region of retina, about one degree from the center of the visual axis. The material has been analyzed by reconstructing adjacent neurons in each array and then identifying systematically the synaptic connections between arrays. Most reconstructions were done manually by tracing the outlines of processes in successive sections onto acetate sheets aligned on a cartoonist's jig. The tracings were then digitized, stacked by computer, and printed with the hidden lines removed. The results have provided rather than the usual one-dimensional account of pathways, a three-dimensional account of circuits. From this has emerged insight into the functional architecture.

Osseointegration interface of calcified bone and endosseous implants

1992 ◽  
Vol 50 (2) ◽  
pp. 1096-1097
Author(s):  
K.E. Krizan ◽  
J.E. Laffoon ◽  
M.J. Buckley
Keyword(s):  
Structure And Function ◽  
Titanium Implants ◽  
En Bloc ◽  
Endosseous Implants ◽  
Ultrastructural Studies ◽  
The Past ◽  
Cacodylate Buffer ◽  
One Year ◽  
And Function

With increase use of tissue-integrated prostheses in recent years it is a goal to understand what is happening at the interface between haversion bone and bulk metal. This study uses electron microscopy (EM) techniques to establish parameters for osseointegration (structure and function between bone and nonload-carrying implants) in an animal model. In the past the interface has been evaluated extensively with light microscopy methods. Today researchers are using the EM for ultrastructural studies of the bone tissue and implant responses to an in vivo environment. Under general anesthesia nine adult mongrel dogs received three Brånemark (Nobelpharma) 3.75 × 7 mm titanium implants surgical placed in their left zygomatic arch. After a one year healing period the animals were injected with a routine bone marker (oxytetracycline), euthanized and perfused via aortic cannulation with 3% glutaraldehyde in 0.1M cacodylate buffer pH 7.2. Implants were retrieved en bloc, harvest radiographs made (Fig. 1), and routinely embedded in plastic. Tissue and implants were cut into 300 micron thick wafers, longitudinally to the implant with an Isomet saw and diamond wafering blade [Beuhler] until the center of the implant was reached.

Use of human autoantibodies and immunoelectron microscopy to study structure and function of the nucleolus and nuclear bodies

1992 ◽  
Vol 50 (1) ◽  
pp. 506-507
Author(s):  
Robert L. Ochs
Keyword(s):  
Electron Microscopy ◽  
Structure And Function ◽  
Nuclear Bodies ◽  
Nuclear Interior ◽  
Coiled Bodies ◽  
Interchromatin Granules ◽  
And Function ◽  
Conventional Electron Microscopy ◽  
Perichromatin Granules ◽  
Perichromatin Fibrils

By conventional electron microscopy, the formed elements of the nuclear interior include the nucleolus, chromatin, interchromatin granules, perichromatin granules, perichromatin fibrils, and various types of nuclear bodies (Figs. 1a-c). Of these structures, all have been reasonably well characterized structurally and functionally except for nuclear bodies. The most common types of nuclear bodies are simple nuclear bodies and coiled bodies (Figs. 1a,c). Since nuclear bodies are small in size (0.2-1.0 μm in diameter) and infrequent in number, they are often overlooked or simply not observed in any random thin section. The rat liver hepatocyte in Fig. 1b is a case in point. Historically, nuclear bodies are more prominent in hyperactive cells, they often occur in proximity to nucleoli (Fig. 1c), and sometimes they are observed to “bud off” from the nucleolar surface.

Depletion and Reconstitution of Active E. Coli Ribosomes

1975 ◽  
Vol 33 ◽  
pp. 640-641
Author(s):  
M. Boublik ◽  
W. Hellmann ◽  
F. Jenkins
Keyword(s):  
Protein Biosynthesis ◽  
Large Subunit ◽  
High Resolution Electron Microscopy ◽  
Small Subunit ◽  
Structure And Function ◽  
Biologically Active ◽  
Biological Macromolecules ◽  
E Coli ◽  
Resolution Electron ◽  
And Function

Correlations between structure and function of biological macromolecules have been studied intensively for many years, mostly by indirect methods. High resolution electron microscopy is a unique tool which can provide such information directly by comparing the conformation of biopolymers in their biologically active and inactive state. We have correlated the structure and function of ribosomes, ribonucleoprotein particles which are the site of protein biosynthesis. 70S E. coli ribosomes, used in this experiment, are composed of two subunits - large (50S) and small (30S). The large subunit consists of 34 proteins and two different ribonucleic acid molecules. The small subunit contains 21 proteins and one RNA molecule. All proteins (with the exception of L7 and L12) are present in one copy per ribosome.This study deals with the changes in the fine structure of E. coli ribosomes depleted of proteins L7 and L12. These proteins are unique in many aspects.

The Laryngeal Epithelium in Reflux

2011 ◽  
Vol 21 (3) ◽  
pp. 112-117 ◽  
Author(s):  
Elizabeth Erickson-Levendoski ◽  
Mahalakshmi Sivasankar
Keyword(s):  
Laryngopharyngeal Reflux ◽  
Critical Role ◽  
Structure And Function ◽  
Laryngeal Disease ◽  
Health And Disease ◽  
And Function ◽  
The Impact

The epithelium plays a critical role in the maintenance of laryngeal health. This is evident in that laryngeal disease may result when the integrity of the epithelium is compromised by insults such as laryngopharyngeal reflux. In this article, we will review the structure and function of the laryngeal epithelium and summarize the impact of laryngopharyngeal reflux on the epithelium. Research investigating the ramifications of reflux on the epithelium has improved our understanding of laryngeal disease associated with laryngopharyngeal reflux. It further highlights the need for continued research on the laryngeal epithelium in health and disease.

Structure and function in the spermatozoon of Bacillus rossiusThe spermatozoon of arthropoda. XIX

1973 ◽  
Vol 44 (1-21012) ◽  
pp. 1-1 ◽  
Author(s):  
B BACCETTI ◽  
A BURRINI ◽  
R DALLAI ◽  
V PALLINI ◽  
P PERITI ◽  
...  
Keyword(s):  
Structure And Function ◽  
And Function

Radiologic Evaluation of Structure and Function of the Sphincter of Oddi

1993 ◽  
Vol 3 (1) ◽  
pp. 13-40 ◽  
Author(s):  
Debra A. Wiedmeyer ◽  
Edward T. Stewart ◽  
Andrew J. Taylor
Keyword(s):  
Sphincter Of Oddi ◽  
Structure And Function ◽  
Radiologic Evaluation ◽  
And Function
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