The Genital System of Temnocephala II.* Further Observations on theSpermatogenesis of Temnocephala novaezealandiae, with particular Reference to the Mitochondria

1984 ◽  
Vol 32 (4) ◽  
pp. 447 ◽  
Author(s):  
JB Williams
Keyword(s):  
Sperm Cell ◽  
Lamellar Body ◽  
Mirror Image ◽  
Genital System ◽  
Long Period ◽  
Dense Bodies ◽  
Cellular Autophagy ◽  
Cell Processes ◽  
Spiral Array ◽  
Chromatoid Bodies

The testis is bounded by a modified epithelium which has strongly phagocytic properties. Cells at synchronized stages of development are united in syncytia but do not form rosettes; the clusters of joined cells are enveloped by epithelial cell processes. A relatively long period of synapsis characterizes the primary spermatocytes. The nucleus passes through a racquet-shaped configuration as it commences to elongate, and later the compacted chromatin transforms into helically wound strands. At the time of centriole reorientation, the intercentriolar lamellar body divides down the middle, separating the mirror-image halves. Components of the intercentriolar body may give rise to the dense centriole caps. The peripheral microtubules form a spiral array in certain segments of the elongated sperm cell, and dense bodies with paracrystalline centres are regularly aligned in the shaft. When chromatoid bodies of animal spermatozoa are associated with aggregated, indented mitochondria. they are probably in process of degradation by cellular autophagy.

The Genital System of Temnocephala. I. Ultrastructural Features of the Differentiating Spermatid of Temnocephala Novaezealandiae, Including Notes on a Possible Correlation Between Cellular Autophagy and Mitochondrial Function.

1983 ◽  
Vol 31 (3) ◽  
pp. 317 ◽  
Author(s):  
JB Williams
Keyword(s):  
Mitochondrial Function ◽  
Sperm Morphology ◽  
Lamellar Body ◽  
Glycogen Metabolism ◽  
Basal Bodies ◽  
Genital System ◽  
Nuclear Region ◽  
Cellular Autophagy ◽  
Early Spermatid

The early spermatid of I: novaezealandiae possesses two centrioles, between which lies a transient lamellar body. The centrioles form the basal bodies of two flagella of the '9+1' type, which remain free throughout spermatogenesis. Following cell elongation and organelle migration, the advanced spermatid is composed of a proximal cytoplasmic mass, a greatly attenuated nuclear region, an elongated mid-piece, an end piece, and the subterminally inserted flagella. There is no acrosome. Rows of glycogen granules occur in the spermatid shaft. Extrusion of nuclear components probably contributes to the modelling and compaction of the nucleus. The mitochondria of the cytoplasmic mass possess indentations filled with membrane whorls; it is proposed that the membrane accumulates in cellular autophagy. Mitochondria in the spermatid shaft are also indented; perhaps autophagic vesicles occupying the invaginations are related to glycogen metabolism. Modified membranes lining the indentations may be sites for the entry of lytic products into the mitochondria. Knowledge of the sperm morphology of Temnocephala assists in the determination of the taxonomic position of the genus.

Ultrastructural Studies on Kronborgia (Platyhelminthes, Fecampiidae) - the Differentiated Vitellocyte of Kronborgia-Isopodicola Blair and Williams

1990 ◽  
Vol 38 (1) ◽  
pp. 79 ◽  
Author(s):  
JB Williams
Keyword(s):  
Glycogen Synthesis ◽  
Lipid Bodies ◽  
Yolk Granules ◽  
Ultrastructural Studies ◽  
The Core ◽  
Dense Bodies ◽  
Cellular Autophagy ◽  
Parasitic Female ◽  
Myelin Figures

In the adult parasitic female form of K. isopodicola, the vitellocyte cytoplasm contains yolk platelets, lipid bodies, glycogen, myelin figures and mitochondria. The platelets consist of an outer granular zone and an opaque core. All platelets are surrounded by several membranes. Many are cloven into segments by fissures containing membranes. Frequently, small peripheral fragments of the granular zone are pared away, and the core undergoes fragmentation by the same process. Spherical dense bodies are found in the cytoplasm. During the cocoon phase, the platelets are often intricately fragmented, and many pieces are paracrystalline. In the newly deposited egg, many platelets comprise only core segments, which are typically paracrystalline, frequently polygonal, and enveloped by multiple membranes. Spherical dense bodies are not encountered at this stage. The platelets are unlike the 'yolk globules' of Digenea, but are similar to vitelline platelets described for polyclads. In morphology and mode of utilisation they bear some resemblance to yolk granules of Amphibia. The membranes are interpreted as isolating membranes of cellular autophagy. Glycogen synthesis is related to autophagic events involved in yolk degradation. The spherical bodies probably represent eggshell granules; complex shell granules, characteristic of other platyhelminths, were not observed in K. isopodicola.

scholarly journals MYELIN IN THE CENTRAL NERVOUS SYSTEM AS OBSERVED IN EXPERIMENTALLY INDUCED EDEMA IN THE RAT

1966 ◽  
Vol 31 (3) ◽  
pp. 397-411 ◽  
Author(s):  
Asao Hirano ◽  
H. M. Zimmerman ◽  
Seymour Levine
Keyword(s):  
Individual Cell ◽  
Careful Study ◽  
Cellular Architecture ◽  
Myelin Sheaths ◽  
Dense Bodies ◽  
Single Axon ◽  
Cell Processes ◽  
The Central Nervous System ◽  
Normal White Matter ◽  
The Brain

The compact arrangement of cells in the normal white matter of the brain makes an analysis of cellular architecture difficult. To overcome this difficulty, cerebral edema was induced in rats by means of the unilateral intracerebral implantation of silver nitrate. Within 48 hr, the brains were fixed by perfusion with glutaraldehyde followed by immersion in Dalton's chrome-osmium. Sections of the callosal radiations were studied in the electron microscope. The untreated hemisphere appeared entirely unaltered, whereas in the edematous hemisphere the edema fluid separated individual cell processes and small groups of them. The myelin sheaths and their relationships to the axons appeared essentially unaltered. In this material, analysis of cellular architecture was relatively easy, and the widely held theory of spiral wrapping could be confirmed. In addition, several other aspects of the myelin and myelin-forming cell relationships became apparent in the edematous tissue. Most of these were later confirmed by extensive and careful study of the nonedematous tissue. These included the presence of occasional isolated cytoplasmic areas in myelin and the presence of two complete sheaths around a single axon. Other observations, such as the appearance of mitochondria and dense bodies within the outer loop and the separation of myelin lamellae, are apparently limited to the edematous tissue.

On nearly-commensurable periods in the restricted problem of three bodies, with calculations of the long-period variations in the interior 2:1 case

1966 ◽  
Vol 25 ◽  
pp. 197-222 ◽  
Author(s):  
P. J. Message
Keyword(s):  
Periodic Solution ◽  
Periodic Solutions ◽  
Large Amplitude ◽  
Restricted Problem ◽  
Small Amplitude ◽  
Minor Planets ◽  
Long Period ◽  
Numerical Integrations ◽  
Period Variations ◽  
The Mean

An analytical discussion of that case of motion in the restricted problem, in which the mean motions of the infinitesimal, and smaller-massed, bodies about the larger one are nearly in the ratio of two small integers displays the existence of a series of periodic solutions which, for commensurabilities of the typep+ 1:p, includes solutions of Poincaré'sdeuxième sortewhen the commensurability is very close, and of thepremière sortewhen it is less close. A linear treatment of the long-period variations of the elements, valid for motions in which the elements remain close to a particular periodic solution of this type, shows the continuity of near-commensurable motion with other motion, and some of the properties of long-period librations of small amplitude.To extend the investigation to other types of motion near commensurability, numerical integrations of the equations for the long-period variations of the elements were carried out for the 2:1 interior case (of which the planet 108 “Hecuba” is an example) to survey those motions in which the eccentricity takes values less than 0·1. An investigation of the effect of the large amplitude perturbations near commensurability on a distribution of minor planets, which is originally uniform over mean motion, shows a “draining off” effect from the vicinity of exact commensurability of a magnitude large enough to account for the observed gap in the distribution at the 2:1 commensurability.

Discussion following the presentation by F. Deubner

1977 ◽  
Vol 36 ◽  
pp. 69-74
Keyword(s):  
List Type ◽  
The Sun ◽  
Type Number ◽  
Harmonic Motion ◽  
Locally Excited ◽  
Long Period ◽  
Coherent Wave ◽  
Short Period ◽  
Global Modes

The discussion was separated into 3 different topics according to the separation made by the reviewer between the different periods of waves observed in the sun :1) global modes (long period oscillations) with predominantly radial harmonic motion.2) modes with large coherent - wave systems but not necessarily global excitation (300 s oscillation).3) locally excited - short period waves.

Organisation in the Structure of the Cytoplasmic Ground Substance

1978 ◽  
Vol 36 (3) ◽  
pp. 627-639
Author(s):  
K.R. Porter
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Random Distribution ◽  
Ground Substance ◽  
The Matrix ◽  
Cell Processes ◽  
Cytoplasmic Ground Substance

Most types of cells are known from their structure and overall form to possess a characteristic organization. In some instances this is evident in the non-random disposition of organelles and such system subunits as cisternae of the endoplasmic reticulum or the Golgi complex. In others it appears in the distribution and orientation of cytoplasmic fibrils. And in yet others the organization finds expression in the non-random distribution and orientation of microtubules, especially as found in highly anisometric cells and cell processes. The impression is unavoidable that in none of these cases is the organization achieved without the involvement of the cytoplasmic ground substance (CGS) or matrix. This impression is based on the fact that a matrix is present and that in all instances these formed structures, whether membranelimited or filamentous, are suspended in it. In some well-known instances, as in arrays of microtubules which make up axonemes and axostyles, the matrix resolves itself into bridges (and spokes) between the microtubules, bridges which are in some cases very regularly disposed and uniform in size (Mcintosh, 1973; Bloodgood and Miller, 1974; Warner and Satir, 1974).

The growth of mica polytypes as studied by conventional and high-resolution TEM

1983 ◽  
Vol 41 ◽  
pp. 174-177
Author(s):  
A. Baronnet ◽  
M. Amouric
Keyword(s):  
Water Pressure ◽  
Point Of View ◽  
Temperature Fields ◽  
Natural Occurrence ◽  
Growth Mechanisms ◽  
Long Period ◽  
High Resolution Tem ◽  
Layer Stacking ◽  
Experimental Works ◽  
Potential Use

The origin of mica polytypes has long been a challenging problem for crystal- lographers, mineralogists and petrologists. From the petrological point of view, interest in this field arose from the potential use of layer stacking data to furnish further informations about equilibrium and/or kinetic conditions prevailing during the crystallization of the widespread mica-bearing rocks. From the compilation of previous experimental works dealing with the occurrence domains of the various mica "polymorphs" (1Mr, 1M, 2M1, 2M2 and 3T) within water-pressure vs temperature fields, it became clear that most of these modifications should be considered as metastable for a fixed mica species. Furthermore, the natural occurrence of long-period (or complex) polytypes could not be accounted for by phase considerations. This highlighted the need of a more detailed kinetic approach of the problem and, in particular, of the role growth mechanisms of basal faces could play in this crystallographic phenomenon.

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).

Neuron-glia relationship during the early postembryonic development of the nervous system in some oligochaetes

1978 ◽  
Vol 36 (2) ◽  
pp. 600-601
Author(s):  
Wiktor Djaczenko ◽  
Carmen Calenda Cimmino
Keyword(s):  
Nervous System ◽  
Glial Cells ◽  
Early Period ◽  
Postembryonic Development ◽  
Ruthenium Red ◽  
The Body ◽  
Tubifex Tubifex ◽  
Growth Stages ◽  
Cell Processes ◽  
Cytoplasmic Processes

The simplicity of the developing nervous system of oligochaetes makes of it an excellent model for the study of the relationships between glia and neurons. In the present communication we describe the relationships between glia and neurons in the early periods of post-embryonic development in some species of oligochaetes.Tubifex tubifex (Mull. ) and Octolasium complanatum (Dugès) specimens starting from 0. 3 mm of body length were collected from laboratory cultures divided into three groups each group fixed separately by one of the following methods: (a) 4% glutaraldehyde and 1% acrolein fixation followed by osmium tetroxide, (b) TAPO technique, (c) ruthenium red method.Our observations concern the early period of the postembryonic development of the nervous system in oligochaetes. During this period neurons occupy fixed positions in the body the only observable change being the increase in volume of their perikaryons. Perikaryons of glial cells were located at some distance from neurons. Long cytoplasmic processes of glial cells tended to approach the neurons. The superimposed contours of glial cell processes designed from electron micrographs, taken at the same magnification, typical for five successive growth stages of the nervous system of Octolasium complanatum are shown in Fig. 1. Neuron is designed symbolically to facilitate the understanding of the kinetics of the growth process.

Adenomatoid Tumor of the Testis, A Mesonephric Hamartoma

1971 ◽  
Vol 29 ◽  
pp. 318-319
Author(s):  
Raoul Fresco ◽  
Mary Chang-Lo
Keyword(s):  
Electron Microscopy ◽  
Epithelial Cells ◽  
Fibrous Tissue ◽  
Salient Feature ◽  
Luminal Surface ◽  
Adenomatoid Tumor ◽  
Ultrastructural Studies ◽  
Epithelial Origin ◽  
Brush Borders ◽  
Cell Processes

Confusion surrounds the nature of the “adenomatoid tumor” of the testis, as evidenced by the large number of synonyms which have been ascribed to it. Various authors have considered the tumor to be of endothelial, mesothelial or epithelial origin. There appears to be no controversy as to the stromal elements of the tumor, which consists mainly of smooth muscle and fibrous tissue. It is the irregular gland-like spaces which have given rise to the numerous theories as to its histogenesis, and even recent ultrastructural studies fail to agree on the origin of these structures.Electron microscopy of a typical intrascrotal adenomatoid tumor showed the gland-like spaces to be lined by epithelial cells (Fig. 1), rich in cytoplasmic tonofibrils and united to each other by numerous desmosomes (Fig. 2). The most salient feature of these epithelial cells was the presence on their luminal surface of numerous long and repeatedly branching microvillous structures of the type known as stereocilia (Fig. 3). These are extremely long slender cell processes which are as much as three to four times the length of those in brush borders.

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