The Structure and Development of the Spermatozoon of Aspiculuris Tetraptera (Nematoda)

1967 ◽  
Vol 2 (4) ◽  
pp. 537-544
Author(s):  
D. L. LEE ◽  
A. O. ANYA
Keyword(s):  
Longitudinal Axis ◽  
Mature Spermatozoon ◽  
Abundant Cytoplasm ◽  
Oriented Parallel ◽  
Aspiculuris Tetraptera

The mature spermatozoon of Aspiculuris tetraptera has a distinct head-like structure and a tail-like structure. The tail contains a long mitochondrion which extends from within the head almost to the posterior end of the tail. Two bundles of microtubules oriented parallel to the longitudinal axis also extend the length of the tail on either side of the mitochondrion. The head of the spermatozoon contains abundant cytoplasm but no nucleus. The DNA of the spermatozoon is in the tail-like structure where it is associated with an electron-dense sheath and the two bundles of microtubules. The head can put out pseudopodia and it is suggested that they may be involved in locomotion or may be acrosome-like. The tail, which structurally resembles a motile appendage, has not been seen to move. This spermatozoon differs markedly in its structure from all others which have been described.

scholarly journals Fabrication of Mesostructured Silica and Titania Rods on Substrates by Using Polycarbonate Membranes

2010 ◽  
Vol 2010 ◽  
pp. 1-4 ◽  
Author(s):  
Norihiro Suzuki ◽  
Yusuke Yamauchi
Keyword(s):  
Electron Microscope ◽  
Longitudinal Axis ◽  
Sem Images ◽  
One Pot ◽  
Polycarbonate Membrane ◽  
Entire Area ◽  
Transmission Electron ◽  
Polycarbonate Membranes ◽  
Fibrous Morphology ◽  
Oriented Parallel

By using the polycarbonate membrane a template, mesoporous silica rods are fabricated on a silicon substrate in one pot. From scanning electron microscope (SEM) images, the creation of fibrous morphology is confirmed over the entire area. The diameter of the obtained rods is consistent with that of the template. Transmission electron microscope (TEM) images revealed that the tubular mesochannels are uniaxially oriented parallel to the longitudinal axis of the silica rods. The mesoporous titania rods with anatase crystalline frameworks are also fabricated.

scholarly journals CENTROSOMES AND MICROTUBULES DURING MEIOSIS IN THE MUSHROOM BOLETUS RUBINELLUS

1971 ◽  
Vol 50 (3) ◽  
pp. 737-745 ◽  
Author(s):  
David J. McLaughlin
Keyword(s):  
Electron Microscope ◽  
Longitudinal Axis ◽  
Spindle Pole ◽  
Middle Part ◽  
Prophase I ◽  
Cytoplasmic Microtubules ◽  
Oriented Parallel ◽  
Relationship Of ◽  
The Relationship

The double centrosome in the basidium of Boletus rubinellus has been observed in three planes with the electron microscope at interphase preceding nuclear fusion, at prophase I, and at interphase I. It is composed of two components connected by a band-shaped middle part. At anaphase I a single, enlarged centrosome is found at the spindle pole, which is attached to the cell membrane. Microtubules mainly oriented parallel to the longitudinal axis of the basidium are present at prefusion, prophase I and interphase I. Cytoplasmic microtubules are absent when the spindle is present. The relationship of the centrosome in B. rubinellus to that in other organisms and the role of the cytoplasmic microtubules are discussed.

Chromoplasts in Rosa rugosa: Development and Chemical Characterization of Tubular Elements

1976 ◽  
Vol 31 (7-8) ◽  
pp. 456-460d ◽  
Author(s):  
Hans-Gunter Wuttke
Keyword(s):  
Fine Structure ◽  
Chemical Composition ◽  
Cross Section ◽  
Early Stage ◽  
Chemical Characterization ◽  
Longitudinal Axis ◽  
Rosa Rugosa ◽  
Polarizing Microscopy ◽  
Oriented Parallel

Abstract 1. Development and fine structure of the chromoplasts in hips of Rosa rugosa have been in­ vestigated by electron and polarizing microscopy. 2. The chromoplasts develop from chloroplasts. During disorganization of the thylakoid system characteristic strutures become visible: ‘oblique’ grana, U-shaped thylakoids, and occassionally ‘thylakoid teeth’ as well as thylakoid anastomoses. - In this early stage, tubules appear in the plastid matrix. They are sometimes connected with membranes, especially with thylakoids. 3. In ripe hips the chromoplasts are packed with tubules. These chromoplast tubules, which attain lengths of up to at least 1.5 μm, are non-ramified and lie parallel to each other. Their diameter is variable, with a mean of 18 nm. They are polygonal in cross-section with electron-dense walls and electron-transparent cores. Association of ellipsoidal osmiophilic globules with the tubules can often be seen. Irregularly swollen remnants of former thylakoids are found in connection with these tubules. In spindle-shaped chromoplasts, the tubules are oriented parallel to the longitudinal axis. Positive birefringence and positive dichroism are observed. 4. The chemical composition of tubule fractions has been analyzed. The tubules contain appreciable amounts of carotenoids, phospho- and glycolipids, and proteins. 5. The origin and development of the tubules is discussed. It appears likely that reorganization of part of the thylakoid system and synthesis of carotenoids are involved in the formation of tubules. 6. The plastids in the yellow autumn leaves of Rosa rugosa contain globules but not tubules.

scholarly journals Ultrastructure and cytochemistry of the mature spermatozoon of Khawia armeniaca (Cholodkovsky, 1915) (Caryophyllidea: Lytocestidae), a parasite of Capoeta capoeta sevangi (De Filippi, 1865) (Teleostei, Cyprinidae)

2020 ◽  
Vol 57 (4) ◽  
pp. 353-360
Author(s):  
M. Matoušková ◽  
M. Bruňanská ◽  
J. Nebesářová ◽  
L. G. Poddubnaya
Keyword(s):  
Anterior Part ◽  
Male Gamete ◽  
Longitudinal Axis ◽  
Mature Spermatozoon ◽  
Ultrastructural Organization ◽  
Cortical Microtubules ◽  
Transmission Electron ◽  
Cytochemical Technique ◽  
First Time ◽  
Region Ii

SummaryThe mature spermatozoon of Khawia armeniaca, a monozoic caryophyllidean parasite of templar fish Capoeta capoeta sevangi (De Filippi, 1865) from the Lake Sevan, Armenia, has been studied using transmission electron microscopy and cytochemical technique of Thiéry (1967) for the first time. The mature spermatozoon of K. armeniaca consists of a single axoneme with the 9+‘1’ trepaxonematan structure, cortical microtubules and nucleus which are situated parallel to the longitudinal axis of the spermatozoon, and a moderately electrondense cytoplasm with glycogen particles. The cortical microtubules are arranged in one continuous semicircle beneath the plasma membrane in Region II and anterior part of Region III of the mature spermatozoon. The two opposite rows of cortical microtubules are observed in the remaining nuclear and at the beginning of the postnuclear part (Regions III, IV) of the male gamete The number of cortical microtubules is remarkably variable in the spermatozoa of various Khawia species. K. armeniaca exhibits the highest number of cortical microtubules in comparison with K. sinensis and K. rossittensis. Glycogen was detected in the cytoplasm of prenuclear (II), nuclear (III) and postnuclear (IV) regions with different ultrastructural organization of the mature spermatozoon of K. armeniaca. Variations of sperm ultrastructural characters within caryophyllideans and other cestodes are discussed.

scholarly journals Microtubules and control of macronuclear ‘amitosis’ in Paramecium

1980 ◽  
Vol 44 (1) ◽  
pp. 135-151
Author(s):  
J.B. Tucker ◽  
J. Beisson ◽  
D.L. Roche ◽  
J. Cohen
Keyword(s):  
Spatial Relationship ◽  
Longitudinal Axis ◽  
Nuclear Shape ◽  
Dorsal Cortex ◽  
Spatially Correlated ◽  
Sliding Mechanism ◽  
Intranuclear Microtubules ◽  
Oriented Parallel ◽  
And Control ◽  
Macronuclear Division

The ‘amitotic’ division of the macronucleus during binary fission in P. tetraurelia includes a detailed sequence of shape changes that are temporally coordinated with the adoption of a series of well-defined positions and orientations inside the cell. The deployment of nucleoplasmic microtubules that is spatially correlated with the shaping ritual is more complex and precise than has been reported previously. Macronuclear division is not amitotic. It is not a simple constriction into two halves. As a dividing macronucleus starts to elongate it becomes dorsoventrally flattened against the dorsal cortex of the organism and assumes an elliptical shape. Concurrently, an elliptical marginal band of intranuclear microtubules assembles that has the same spatial relationship to nuclear shape as the marginal microtubules assembles that has the same spatial relationship to nuclear shape as the marginal microtubule bands of certain elliptical vertebrate blood cells have to cell shape. The band breaks down as further elongation occurs and the nucleus adopts the shape of a straight and slender sausage. Most of the intranuclear microtubules assemble as elongation starts and break down shortly after elongation is completed; the majority are oriented parallel to the longitudinal axis of the nucleus throughout elongation. Some of them are attached to nucleoli and are coated with granules which are almost certainly derived from the cortices of nucleoli. The peripheral concentration, interconnexion, orientation, and overlapping arrangement of microtubules, and the reduction in microtubule number per nuclear cross-section as elongation proceeds at a rate of about 40 micrometers min-1, are all compatible with the provision of a microtubule sliding mechanism as the main skeletal basis for elongation. There are indications that this mechanism is augmented by anchorage and/or active propulsion of nucleoli that may perhaps facilitate fairly equitable segregation of chromosomal material to daughter nuclei.

scholarly journals THE EFFECTS OF ENDOTOXIN ON VASCULAR ENDOTHELIUM

1969 ◽  
Vol 129 (5) ◽  
pp. 833-848 ◽  
Author(s):  
J. M. McGrath ◽  
G. J. Stewart
Keyword(s):  
Methylene Blue ◽  
Endothelial Cells ◽  
Vascular Endothelium ◽  
Longitudinal Axis ◽  
Mesenteric Arteries ◽  
Ethylene Dichloride ◽  
Experimental Animals ◽  
Deep Blue ◽  
Fat Deposits ◽  
Oriented Parallel

This study was undertaken to develop a technique for the preparation of sheets of endothelial cells and to investigate the effects of bacterial endotoxin on large numbers of cells from continuous sheets of vascular endothelium. Rabbits were divided into one control and two experimental groups. The experimental animals received intracardially an LD50 dose of Escherichia coli endotoxin. 1 and 24 hr postinjection, the vessels of the animals were perfused with glutaraldehyde in Millonig's buffer with methylene blue as a marker. Pieces of mesentery containing arteries were postfixed in buffered glutaraldehyde, dehydrated, and placed in acetone (to remove fat deposits). The surrounding connective tissue was stripped from the mesenteric arteries, and segments of the vessels were slit longitudinally, flattened out, and firmly affixed to a sheet of cork with fine mounting pins. A 3% solution of Formvar in ethylene dichloride was pipetted onto the luminal surfaces of the vessels. The endothelial cells were impregnated with and adhered to the Formvar and, after soaking overnight in 10 N NaOH, could be stripped from the vessel walls as monolayers. Sheets of Formvar-impregnated cells were temporarily mounted on glass slides in aqueous methylene blue and examined by phase and bright-field microscopy. Methylene blue stained the nuclei a deep blue and the cytoplasm faintly, but cell outlines were indistinct. Endothelial sheets from control rabbits had smooth, elliptical nuclei oriented parallel to the longitudinal axis of the cells and irregularly distributed over a smooth background with faint longitudinal striations. Essentially every cell in endothelial sheets from endotoxin-injected animals appeared to be severely damaged. Cell sheets from 24 hr posttreatment animals exhibited the same type of, but more extensive, damage than that observed in 1 hr posttreatment animals. The most prominent features of the damaged endothelium were distorted nuclei, apparent nuclear vacuolization, and missing nuclei. Unstained platelets and plaques were present on the surfaces of the specimens from the experimental animals only. Stained and unstained red blood cells were also dispersed over the luminal surfaces of the endotoxin-treated vessels.

Microfilaments in plant vascular cells

1980 ◽  
Vol 58 (7) ◽  
pp. 807-815 ◽  
Author(s):  
M. V. Parthasarathy ◽  
T. C. Pesacreta
Keyword(s):  
Actin Filaments ◽  
Vascular Tissue ◽  
Longitudinal Axis ◽  
Vascular Cells ◽  
Microfilament Bundle ◽  
Microfilament Bundles ◽  
Size And Morphology ◽  
Oriented Parallel ◽  
Peripheral Regions

Microfilaments 50–70 Å (Å = 0.1 nm) in diameter are commonly found in vascular tissue of elongating roots and stems of many plants. Such microfilaments occur in bundles in peripheral regions of elongating or differentiating vascular cells, and are usually oriented parallel to the longitudinal axis of the cells. Although the longest microfilament bundle we have measured is about 15 μm, we suspect that the bundles are at least as long as the cells that contain them. The bundles are 0.1–0.4 μm in width and are often in apparent contact with organelles, but there is no definite indication of their being anchored to plasmalemma or any organelle. The microfilaments are comparable in size and morphology to actin filaments. The distribution of microfilament bundles in the vascular tissue of various plants and the possible function of the bundles is discussed.

scholarly journals A new species of Pachytrocha Kent, 1882 (Ciliophora, Peritrichia: Vaginicolidae)

Zootaxa ◽  
2009 ◽  
Vol 2198 (1) ◽  
pp. 61-66
Author(s):  
ELENA G. BOSHKO ◽  
LYUDMILA A. KONSTANTYNENKO
Keyword(s):  
New Species ◽  
Sewage Treatment ◽  
Longitudinal Axis ◽  
The Body ◽  
Treatment System ◽  
Oriented Parallel ◽  
A New Species ◽  
Sewage Treatment System

The peritrich ciliate Pachytrocha zhytomirensis n. sp. is described from the sewage treatment system of Zhytomir (Ukraine). The new species is characterized by an elongate, subgeniculate lorica sheltering a single zooid with an annular ridge and a peristomial lip thickened noticeably near the entrance to the infundibulum. When contracting, the upper part of the cell bends toward the wall of the lorica and the inflated edge of the peristomial lip covers the body. The macronucleus is ribbon-like and oriented parallel to the longitudinal axis of the cell. Cothurnia asymmetrica Sommer, 1951 is recognized as a synonym of Pachytrocha cothurnoides Kent, 1882.

Formation of two microtubule-nucleating sites which perform differently during centrosomal reorganization in a mouse cochlear epithelial cell

1995 ◽  
Vol 108 (4) ◽  
pp. 1333-1345 ◽  
Author(s):  
J.B. Tucker ◽  
M.M. Mogensen ◽  
C.C. Paton ◽  
J.B. Mackie ◽  
C.G. Henderson ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Apical Cell ◽  
Organ Of Corti ◽  
Longitudinal Axis ◽  
Sequence Of Events ◽  
Pericentriolar Material ◽  
High Concentrations ◽  
Oriented Parallel ◽  
A Site

This report provides evidence for the formation of a cell surface-associated centrosome with two spatially discrete microtubule-nucleating sites that perform differently; the minus ends of microtubules remain anchored to one site but escape from the other. Centrosomal reorganization in the cells in question, outer pillar cells of the organ of Corti, indicates that its pericentriolar material becomes intimately associated with the plasma membrane at the two nucleating sites. Two large microtubules bundles assemble in each cell. A beam which includes about 1,300 microtubules spans most of the cell apex. It is positioned at right angles to a pillar with about 4,500 microtubules which is oriented parallel to the cell's longitudinal axis. The beam's microtubules elongate from, and remain attached to, a centrosomal region with two centrioles which acts as a microtubule-nucleating site. However, the elongating microtubules do not radiate from the immediate vicinity of the centrioles. During beam assembly, the minus ends of the microtubules are concentrated together close to the plasma membrane (less than 0.2 micron away in many cases) at a site which is located to one side of the cell apex. High concentrations of the pillar's microtubules elongating from one particular site have not been detected. Analyses of pillar assembly indicate that the following sequence of events occurs. Pillar microtubules elongate from an apical cell surface-associated nucleating site, which becomes more distantly separated from the centriolar locality as cell morphogenesis progresses. Microtubules do not accumulate at this apical nucleating site because they escape from it. They migrate down to lower levels in the cell where the mature bundle is finally situated and their plus ends are captured at the cell base.

Ultrastructure of human spleen in transmission and scanning electron microscope

Biologia ◽  
2009 ◽  
Vol 64 (2) ◽  
Author(s):  
Štefan Polák ◽  
Paulína Gálfiová ◽  
Ivan Varga
Keyword(s):  
Electron Microscope ◽  
Blood Circulation ◽  
Three Dimensional ◽  
Longitudinal Axis ◽  
Human Spleen ◽  
Intimate Contact ◽  
Reticular Cells ◽  
Oriented Parallel ◽  
Scanning Electron ◽  
Fibroblastic Reticular Cells

AbstractDespite new information concerning functional morphology of spleen, there are still some inaccuracies mostly regarding the spleen blood circulation. Billroth’s (splenic) cords are formed from three-dimensional network of fibroblastic reticular cells located among branched sinuses. Results from our study using scanning electron microscopy confirm an intimate contact between adjacent reticular cells and erythrocytes. Arterial terminals can be observed in the Billroth’s cords. The wall of sinuses reminds a sieve and it is lined with a special type of endothelium. In electron microscope, endothelial cells look like rods oriented parallel to the longitudinal axis of sinuses. Based on our observations fibroblastic reticular cells change to fixed phagocytes under no circumstances, hence they do not participate in phagocytosis. They may have a recognition function for cells circulating around them. According to our opinion, the open and the closed blood circulation are present in the human spleen simultaneously. Blood flowing in the closed circulation can help “absorption” of extra-vascular liquid and the blood elements into the vascular lumen. Due to sporadic occurrence of smooth muscle cells in the capsule and trabeculae, we assume that human spleen is not a blood reservoir, unlike the spleen in some other animals.

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