scholarly journals The Ultrastructure of the Epicuticular Interference Reflectors of Tiger Beetles (Cicindela)

1985 ◽  
Vol 117 (1) ◽  
pp. 87-110
Author(s):  
T.D. SCHULTZ ◽  
M.A. RANKIN
Keyword(s):  
Refractive Index ◽  
Dense Material ◽  
Dense Layer ◽  
Surface Reflectance ◽  
Structural Coloration ◽  
Electron Dense Material ◽  
Tiger Beetles ◽  
Electron Lucent

Tiger beetles of the genus Cicindela exhibit iridescent structural coloration due to the presence of a non-ideal multilayer interference reflector located in the outermost 2 μm of the integument. The reflector is composed of alternating layers of electron-lucent and electron-dense material. This series of layers was distinguished from chitinous procuticle by its position, ultrastructure and solubility in dilute KOH. The reflector appears homologous with the inner epicuticle of current models. Measurements of surface reflectance, refractive index and the dimensions of the alternating layers suggests that the dense layer has a refractive index (RI) near 2.0 and may be a melanoprotein.

scholarly journals Developmental Changes in the Interference Reflectors and Colorations of Tiger Beetles (Cicindela)

1985 ◽  
Vol 117 (1) ◽  
pp. 111-117
Author(s):  
T. D. SCHULTZ ◽  
M. A. RANKIN
Keyword(s):  
Refractive Index ◽  
Electron Density ◽  
Dense Material ◽  
Developmental Changes ◽  
Dense Layer ◽  
Electron Dense Material ◽  
Interference Colour ◽  
Tiger Beetles ◽  
Colour Development

Samples of cicindelid cuticle were examined at various stages of adult ecdysis. The multilayered potential reflector was secreted in the initial stages of the moult, verifying that it is not tectocuticle and supporting the contention that it is a form of inner epicuticle. At early stages of ecdysis, the electron-dense layers were visible only when the section was post-stained. During post-ecdysial colour development, the dense layer increased in inherent electron density. Concurrently, the reflector increased in refractive index and the interference coloration increased in intensity and wavelength of maximum reflectance. Black pigment was also deposited simultaneously within the outer portion of the cuticle. It is proposed that electron-dense material was deposited in situ within the inner epicuticle after ecdysis, thereby increasing the wavelength and reflectance of interference colour.

Spore wall ultrastructure in the liverwort Fossombronia longiseta

1984 ◽  
Vol 62 (9) ◽  
pp. 1871-1879 ◽  
Author(s):  
M. P. Steinkamp ◽  
W. T. Doyle
Keyword(s):  
Spore Wall ◽  
Dense Material ◽  
White Line ◽  
Electron Dense Material ◽  
Transmission Electron ◽  
Wall Ultrastructure ◽  
Electron Microscopes ◽  
Electron Lucent

Mature spores of Fossombronia longiseta (Metzgeriales, Codoniaceae) were examined with both scanning and transmission electron microscopes. Sporoderms are highly sculptured. The distal face markings consist of parallel ridges (cristae) or spines. The flattened proximal face has a series of short spinelike cristae, and a triradiate ridge mark sometimes is apparent. In section, the sporoderm consists of an intine and a two-layered exine. The inner exine layer consists of two lamellae, each of which contains a series of long, thin (3–4 nm), closely spaced, electron-lucent subunits; the subunits are separated by electron-dense material. The more or less solid outer exine consists of highly irregularly shaped lamellae, which also have a "white line" component. Amorphous, electron-dense material permeates these lamellae and fills the channels between the lamellae. The intine and much of the electron-dense material of the exine is removed by acetolysis. Spore wall ultrastructure in this species is complex compared with other species of the Metzgeriales and Jungermanniales that have been studied so far.

scholarly journals Ultrastructure of the cirrus sac of the male strobila of Shipleya inermis (Fuhrmann, 1908) (Cestoda: Cyclophyllidea)

2011 ◽  
Vol 48 (3) ◽  
pp. 174-183 ◽  
Author(s):  
L. Poddubnaya ◽  
N. Pospekhova
Keyword(s):  
Secretory Granules ◽  
Ejaculatory Duct ◽  
Muscle Layer ◽  
Dense Material ◽  
Electron Dense Material ◽  
Peripheral Muscle ◽  
Lateral Margins ◽  
Limnodromus Scolopaceus ◽  
Longitudinal Muscles ◽  
Electron Lucent

AbstractThis study was designed to provide information on the ultrastructural traits of the cirrus sac of the male strobila of the dioecious cyclophyllidean tapeworm, Shipleya inermis Fuhrmann, 1908 from the small intestine of long-billed dowitchers, Limnodromus scolopaceus, in Chukotka, Russia. The cirrus sac is characterised by a thick muscular wall (comprising about 20 layers of longitudinal muscles) with the muscle cells being located outside the wall along the peripheral muscle layer and the presence of a thick, fibrillar septum inside the sac along the inner muscle layer of the wall. The epithelium of the intrabursal ducts is syncytial and has sunken perikarya. The ejaculatory duct is characterised by surface luminal microvilli and a large number of the sunken perikarya producing electron-dense secretory granules, which discharge into the duct lumen as an apocrine secretion. The cirrus is armed with two types of sclerotized structures formed by its epithelium, hooks of about 25 μm in length and microthrix-like structures on its luminal surface. The hooks are sigmoid in shape, have a blade circular in transverse section and about 3.5 μm in width, and taper at both extremities. The hook body consists of moderately electron-dense material mixed with a more electron-dense material and an electron-lucent core. The hook roots lie within the cirrus epithelium, where their lateral margins are composed of a thin covering of electrondense material with narrow lateral extensions. The usefulness of the ultrastructural characters of the cirrus sac as indicators of phylogenetic relationships within the Eucestoda is discussed.

Comparative ultrastructure of the spermatozoa of Inermicapsifer guineensis and Inermicapsifer madagascariensis (Cestoda, Anoplocephalidae, Inermicapsiferinae), intestinal parasites of rodents in Senegal

1994 ◽  
Vol 72 (9) ◽  
pp. 1633-1638 ◽  
Author(s):  
Cheikh Tidiane Bâ ◽  
Bernard Marchand
Keyword(s):  
Anterior Extremity ◽  
Posterior Extremity ◽  
Intestinal Parasites ◽  
Sperm Nucleus ◽  
Dense Material ◽  
Cortical Microtubules ◽  
Electron Dense Material ◽  
Apical Cone ◽  
Comparative Ultrastructure ◽  
Electron Lucent

Spermatozoa of Inermicapsifer guineensis and Inermicapsifer madagascariensis are filiform and tapered at both extremities. The anterior extremity exhibits an apical cone of electron-dense material and two helical ridges. The axoneme, of the 9 + "1" pattern, is surrounded over part of its length by a sheath of electron-dense material. At the posterior extremity the cytoplasm contains electron-dense material. In regions III and IV of the spermatozoa the cytoplasm is subdivided into compartments of electron-lucent material limited by irregularly spaced walls of electron-dense material. The sperm nucleus is a compact cord wound in a spiral around the axoneme. Cortical microtubules are helically arranged down the length of the spermatozoa except at the posterior extremity where they run parallel to the spermatozoon axis. In I. madagascariensis, cortical microtubules may not extend as far as the posterior extremity of the spermatozoa; the dense periaxonemal material exists in regions I to IV of the spermatozoon and the nucleus never coils more than once around the axoneme.

The ultrastructure of the pseudohaptoral squamodiscs of Diplectanum aequans (Monogenea)

Parasitology ◽  
1981 ◽  
Vol 82 (2) ◽  
pp. 231-240 ◽  
Author(s):  
M. K. Shaw
Keyword(s):  
Dense Material ◽  
Prominent Feature ◽  
Electron Dense Material ◽  
Dense Membrane ◽  
Membrane Bound ◽  
Epidermal Membrane ◽  
Electron Lucent

SUMMARYThe ultrastructure of the pseudohaptoral squamodiscs of the monogenean Diplectanum aequans is described. The most prominent feature of the squamodisc is the presence of epidermally-embedded spines which are covered by the outer epidermal membrane. These spines, which are ‘hollow’, are composed of a moderately electron-dense material with denser fibrils embedded within it. The squamodisc epidermis is similar in appearance to the haptor epidermis, with the exception of the epidermis ‘inside’ the spines. Here the epidermis contains free ribosomes and stacks of alternating electron-lucent/electron-dense, membrane-bound sacs. The arrangement of the musculature of the spines is described. The free, prehensile, edges of the squamodiscs contain numerous radially orientated nerves, some of which are assumed to be mechano-receptors.

Comparative Morphology of Intercellular Bridges Between Developing Germ Cells of the Ovary

1970 ◽  
Vol 28 ◽  
pp. 328-329
Author(s):  
J. R. Ruby ◽  
R. F. Dyer ◽  
R. G. Skalko ◽  
R. F. Gasser ◽  
E. P. Volpe
Keyword(s):  
Germ Cells ◽  
Rana Pipiens ◽  
Comparative Morphology ◽  
Dense Material ◽  
Individual Species ◽  
Microscope Examination ◽  
Electron Dense Material ◽  
Intercellular Bridges ◽  
Cytoplasmic Side ◽  
Intercellular Connections

An electron microscope examination of fetal ovaries has revealed that developing germ cells are connected by intercellular bridges. In this investigation several species have been studied including human, mouse, chicken, and tadpole (Rana pipiens). These studies demonstrate that intercellular connections are similar in morphology regardless of the species.Basically, all bridges are characterized by a band of electron-dense material on the cytoplasmic side of the tri-laminar membrane surrounding the connection (Fig.l). This membrane is continuous with the plasma membrane of the conjoined cells. The dense material, however, never extends beyond the limits of the bridge. Variations in the configuration of intercellular connections were noted in all ovaries studied. However, the bridges in each individual species usually exhibits one structural characteristic seldom found in the others. For example, bridges in the human ovary very often have large blebs projecting from the lateral borders whereas the sides of the connections in the mouse gonad merely demonstrate a slight convexity.

The ultrastructure of M1-a-mediated resistance to powdery mildew infection in barley

1975 ◽  
Vol 53 (22) ◽  
pp. 2589-2597 ◽  
Author(s):  
H. H. Edwards
Keyword(s):  
Powdery Mildew ◽  
Host Cell ◽  
Electron Density ◽  
Epidermal Cells ◽  
Dense Material ◽  
Ultrastructural Changes ◽  
Electron Dense Material ◽  
Host Cytoplasm ◽  
Powdery Mildew Infection ◽  
Cell Protoplast

M1-a-mediated resistance in barley to invasion by the CR3 race of Erysiphe graminis f. sp. hordei does not occur in every host cell with the same speed and severity. In some cells ultrastructural changes within the host cell as a result of resistance will occur within 24 h after inoculation, whereas in other cells these changes may take up to 72 h. In some cells the ultrastructural changes are so drastic that they give the appearance of a hypersensitive death of the host cell, whereas in other cells the changes are very slight. In any case, at the end of these changes the fungus ceases growth. The ultrastructural changes occur in penetrated host epidermal cells as well as non-infected adjacent epidermal and mesophyll cells.The following ultrastructural changes have been observed: (1) an electron-dense material which occurs either free in the vacuole or adhering to the tonoplast (the material is granular or in large clumps); (2) an increased electron density of the host cytoplasm and nucleus; (3) a breakdown of the tonoplast so that the cytoplasmic constituents become dispersed throughout the cell lumen; and (4) the deposition of papillar-like material in areas other than the penetration site. The first three changes take place within the host cell protoplasts and are directly attributable to the gene M1-a. These changes are typical of stress or incompatibility responses and thus M1-a appears to trigger a generalized incompatibility response in the presence of race CR3. The papillar-like material occurs outside the host cell protoplast in the same manner as the papilla and probably is not directly attributable to M1-a.

scholarly journals Structural Coloration in Caloenas Nicobarica Pigeons and Refractive Index Modulated Sensing

2018 ◽  
Vol 6 (9) ◽  
pp. 1701218 ◽  
Author(s):  
Ijaz Rashid ◽  
Muhammad Umair Hassan ◽  
Abbas Khandwalla ◽  
Rayan Mohammed Ameen ◽  
Ali Kemal Yetisen ◽  
...  
Keyword(s):  
Refractive Index ◽  
Structural Coloration

Visualization of changes in ciliary tip configuration caused by sliding displacement of microtubules in macrocilia of the ctenophore Beroe

1985 ◽  
Vol 79 (1) ◽  
pp. 161-179 ◽  
Author(s):  
S.L. Tamm ◽  
S. Tamm
Keyword(s):  
Electron Microscopy ◽  
Dense Material ◽  
Bend Angle ◽  
Two Dimensional ◽  
Electron Dense Material ◽  
Central Pair ◽  
Rest Position ◽  
Recovery Stroke ◽  
Dimensional Models ◽  
As If

Macrocilia from the lips of the ctenophore Beroe consist of multiple rows of ciliary axonemes surrounded by a common membrane, with a giant capping structure at the tip. The cap is formed by extensions of the A and central-pair microtubules, which are bound together by electron-dense material into a pointed projection about 1.5 micron long. The tip undergoes visible changes in configuration during the beat cycle of macrocilia. In the rest position at the end of the effective stroke (+30 degrees total bend angle), there is no displacement between the tips of the axonemes, and the capping structure points straight into the stomach cavity. In the sigmoid arrest position at the end of the recovery stroke (−60 degrees total bend angle), the tip of the macrocilium is hook-shaped and points toward the stomach in the direction of the subsequent effective stroke. This change in tip configuration is caused by sliding displacement of microtubules that are bound together at their distal ends. Electron microscopy and two-dimensional models show that the singlet microtubule cap acts as if it were hinged to the ends of the axonemes and tilted to absorb the microtubule displacement that occurs during the recovery stroke. The straight and hooked shapes of the tip are thought to help the ctenophore ingest prey.

The apical structure in Perophora annectens (tunicate) spermatozoa: fine structure, differentiation and possible role in fertilization

1984 ◽  
Vol 66 (1) ◽  
pp. 175-187
Author(s):  
M. Fukumoto
Keyword(s):  
Fine Structure ◽  
Golgi Apparatus ◽  
Dense Material ◽  
Electron Dense Material ◽  
Extracellular Materials ◽  
Small Blister

The apical structure in Perophora annectens spermatozoa is approximately 4 micron in length and it is helically coiled. Its major component is a striated structure, which may be analogous to a perforatorium. The plasmalemma enclosing the anterior quarter of the apical structure is covered by extracellular materials, the anterior ornaments. During spermiogenesis, the apical structure is first recognized as a small blister of the plasmalemma at the apex of the young spermatid. It develops into a conical protrusion and then into a finger-like process (approximately 1 micron in length). This process is transformed into an elongated process (approximately 4 micron in length) with electron-dense material in its core. Finally, the elongated process is helically coiled to form an apical structure in which electron-dense material forms dense striations. Vesicles (50-70 nm in diameter), presumably derived from the Golgi apparatus, have been recognized in the blisters of younger spermatids, and can be followed through to the finger-like process. In the finger-like process these vesicles are transformed into smaller vesicles (20-30 nm in diameter), which probably fuse with the anterior plasmalemma of the finger-like process. This suggests that chorion lysin(s) is associated with the anterior membrane enclosing the apical structure in these spermatozoa.

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