Hollow Canal Research Articles

“Horsetail” Inclusions in the Ural Demantoids: Growth Formations

The term “demantoid”, first proposed in 1856 by the famous Finnish mineralogist Nils von Nordensheld, refers to a highly dispersed yellow-green mineral from the Central Urals placers. In 1874, it was found to be a gem variety of andradite garnet. “Horsetail” inclusions are considered a sign of the Ural type demantoid. Although these inclusions are large (visible to the naked eye), their diagnostics remains debatable: some researchers attribute them to byssolite (amphibole-asbestos), others consider them chrysotile. We investigated the horsetail inclusions in the Ural demantoids through various methods: optical microscopy, scanning electron microscopy (SEM), Raman spectrometry, X-ray powder diffraction, and thermal analysis. In most cases, “horsetail” inclusions in the Ural demantoid were represented by hollow channels and only the outcrops, on the demantoid surface, were occasionally filled with serpentine (established by SEM); in one case, magnetite was observed. Hollow canals were usually collected not in bundles, such as a “horsetail”, but in fans, sometimes curved into cones. The structure of the grains was spheroidal, sectorial, and sometimes had induction surfaces, which, to the periphery of the grain, were replaced by tubular channels assembled in a fan. The specifics of the growth of the “horsetail” inclusions of the demantoid grains can be explained by the decompression conditions that arose when the ultrabasites (a crust-mantle mixture) were squeezed upwards during collision.

Teaching and Learning Guide for: Suez: A hollow canal in need of peopling. Currents and stoppages in the historiography, 1859–1956

Teaching and Learning Guide for: Suez: A hollow canal in need of peopling. Currents and stoppages in the historiography, 1859–1956

Suez: A hollow canal in need of peopling. Currents and stoppages in the historiography, 1859–1956

AbstractSince its excavation took off in 1859 in Ottoman‐Egyptian territory, the Suez Canal has conveyed much more than armies or cargoes. This essay dives into the currents and stoppages in the historiography of the Suez Canal and its brand‐new cities between 1859, when the project began, and 1956, when the Egyptian government nationalized this waterway. Writings on the 19th and early 20th‐century history of the Suez Canal have followed a course of their own, quite divergent from mainstream historical scholarship on modern Egypt. The Suez Canal has funneled political aspirations ranging from the colonial to the semicolonial and the nationalist, ideas on its built environment, utopias about a cosmopolitan society, and experiences of actual social dystopias. This essay suggests that scholars need to pay attention to labor and migration in order to people the history of the Suez Canal and its surrounding region, for this waterway not to remain the hollow ditch it has been so far in most of its pre‐1956 historiography.

Stigma, pollen tube transmitting tract, and epidermal micromorphology of the style of Sarracenia purpurea (Sarraceniaceae)

Entomophilous flowers of the genus Sarracenia have a unique umbrella-shaped style, which consists of a broadened and flattened umbrella canopy and a thin cylindrical umbrella stalk. Anatomical and micromorphological features of the style of Sarracenia purpurea L. were studied using light microscopy and scanning electron microscopy. This study found that the pollen tube transmitting tracts (PTTTs) start as a semi-solid canal filled with endotrophic conducting tissue, and run from the peripheral to the center of the canopy where the PTTT becomes a hollow canal supported by ectotrophic conducting tissue. The presence of stomata on the epidermis of the canopy and chloroplasts in its ground parenchyma indicate photosynthetic activities. Convex epidermal cells with intense cuticular striations on the canopy that are similar yet different from those on various regions of the sepals and petals indicate that it may provide contrasting visual cues for pollinators. Multicellular secretory glands and trichomes, which may provide olfactory cues and tactical cues respectively, are also found on the canopy. Thus, the stylar umbrella not only serves as a region for pollen grain capture, pollen germination, and pollen tube transmission but may also play an important role during pollinator–flower interactions.

Comparative Study on the Bisexual Flower and Unisexual Male Flower of Xanthoceras sorbifolia Bunge

Semi-thin sectioning and electron microscopy were used to observe and analyze the development processes in the bisexual flower and unisexual male flower of Xanthoceras sorbifolia Bunge. The results show that:(1) At the early microspore development stage,there is no obvious difference between these two different kinds of flowers. At the uninuclear phase of microspore development when the cell walls thicken,lip cells do not form in the bisexual flower,but develop in the unisexual male flower. At the mature microspore stage,the lip cells form completely and the anther forms a double heart-shape in the unisexual male flower. However,the anther has not broken completely and can not disperse pollen.(2) In the bisexual flower,the ovary has two rooms,the cells are closely packed,the stigmas are cylindrical with papillate cells,and there is a hollow canal inside the style. However,in the unisexual male flower,the development of stigmas cease without the formation of a hollow canal inside the style,the ovarian rooms shrink,and the embryo sac degenerates.(3) The tapetum cells of the unisexual male flower contain many protein bodies,amyloplasts,vacuoles,and Ubisch bodies,and the tapetum cells completely disappear at the later microspore development stage. However,these organelles become less abundant in tapetum cells of the bisexual flower,and the tapetum cells do not completely disappear.(4) The pollen cell wall thickens without germination apertures in the bisexual flower,whereas in the unisexual male flower there are three germination apertures on the pollen grains,and many vacuoles,protein bodies,and liposomes accumulate in the pollen grains.

Equisetum

Equisetum

Microanatomy of the incisive canal using three-dimensional reconstruction of microCT images: An ex vivo study

The purpose of this study was to investigate the general structure of the incisive canal (IC) using 3-dimensional reconstruction and to classify into various types according to several criteria. The materials used in the study were 56 anterior maxillae harvested from human cadavers. The specimens were scanned with microscopic computerized tomography (microCT), and the resulting microCT images were reconstructed in 3 dimensions. Many ICs had 1 foramen inferiorly and 2 foramina superiorly, and the separating level was just beneath the nasal floor. The middle part of the IC was not always a single hollow canal. Single-channel, 2-channel, 3-channel, and even 4-channel ICs were observed. The ICs were classified into 4 types according to the lateral shape of the canal: vertical-straight, vertical-curved, slanted-straight, and slanted-curved. This study disclosed the detailed morphologic features of the IC, which will be helpful in the placement of local anesthesia or implants.

Cross-repressive interactions betweenLrig3and netrin 1 shape the architecture of the inner ear

The sense of balance depends on the intricate architecture of the inner ear, which contains three semicircular canals used to detect motion of the head in space. Changes in the shape of even one canal cause drastic behavioral deficits, highlighting the need to understand the cellular and molecular events that ensure perfect formation of this precise structure. During development, the canals are sculpted from pouches that grow out of a simple ball of epithelium, the otic vesicle. A key event is the fusion of two opposing epithelial walls in the center of each pouch, thereby creating a hollow canal. During the course of a gene trap mutagenesis screen to find new genes required for canal morphogenesis, we discovered that the Ig superfamily protein Lrig3 is necessary for lateral canal development. We show that this phenotype is due to ectopic expression of the axon guidance molecule netrin 1 (Ntn1), which regulates basal lamina integrity in the fusion plate. Through a series of genetic experiments, we show that mutually antagonistic interactions between Lrig3 and Ntn1 create complementary expression domains that define the future shape of the lateral canal. Remarkably, removal of one copy of Ntn1 from Lrig3 mutants rescues both the circling behavior and the canal malformation. Thus, the Lrig3/Ntn1 feedback loop dictates when and where basement membrane breakdown occurs during canal development, revealing a new mechanism of complex tissue morphogenesis.

Computer-based extraction of the inferior alveolar nerve canal in 3-D space

Computed tomography (CT) is increasingly employed in orthodontic treatment. One of the most successful applications is in dental implantology, in which an artificial root is surgically inserted into the jawbone to provide anchorage for a dental prosthesis. For successful implant surgery, it is crucial to locate internal structures such as the inferior alveolar nerve canal (IAC). This paper presents a computerized technique for extracting the IAC. To facilitate the extraction, we first generate panoramic CT images (panoramics) by reformatting the original CT images. The panoramics are a series of cross-sectional images along curved planes through the mandible (lower jawbone). Hollow canals are subsequently detected by analyzing the voxel intensities and 3-D gradient orientations in the panoramics. The axis of the IAC is then traced out by a novel 3-D line-tracking technique. The method is effective for extracting the IAC despite the open structure of the surrounding bone.

Structures involved in production, secretion and injection of the venom produced by the caterpillar Lonomia obliqua (Lepidoptera, Saturniidae)

The number of accidents caused by injection of the venom of Lonomia obliqua caterpillars in Southern Brazil has increased in the last years. Even though this kind of envenomation has an important social and medical impact, nothing is known about the cellular structures responsible for the production and secretion of this venom. Here we identify and analyse morphological structures possibly responsible for the production and secretion of the active principles of the venom, as well as the histological relationship of these structures with the urticating spines of L. obliqua. Detailed microscopic observations showed that: (a) L. obliqua has a complex tegument, with several cuticular specializations, (b) there are no pores along the tegument neither in the spines and (c) the spines bear a hollow canal—where the venom is deposited—and an area that can be easily broken when touched, releasing the venom. Histological and histochemical techniques revealed that: (a) there is no single gland cell that produces the venom, (b) a secretory epithelium, composed of cells containing vesicles that increase in size and number as they reach the apical region, underlies the tegument and the spines and is responsible for secretion of the venomous substances and (c) the venom is deposited in the subcuticular space and at the tips of the spines.

Preservation of Devonian Chemotrophic Filamentous Bacteria in Calcite Veins

Filamentous and possible coccoid bacteria are preserved in calcite vein-fills cutting Devonian lacustrine limestones in the Tynet Burn fish bed near Fochabers, N.E. Scotland. Filamentous bacteria grew into open space off the walls offractures and are concentrated as clumps on some detrital grains. The filaments were coated by iron hydroxide and are now represented by hollow canals 0.3-0.4 gm diameter enclosed in a sheath of acicular hematite crystals each 2 ,um long by 0.2 ,um broad. Possible coccoid bacteria are represented by hematite spheres 0.5 to 2 gm diameter. The bacteria grew in cracks formed by deformation of the sediments after initial compaction and formation of calcareous concretions. Fossil fish are preserved in red and purple colors and the surrounding matrix displays a halo of oxidation which is considered to have been bacterially mediated. Bacterial invasion of sediments took place during lowstands of the Middle Devonian Orcadian Lake when the sediment was in the vadose zone. A clear association is seen between the bacteria-bearing veins and reddening of the succession.

TAXONOMY AND DISTRIBUTION OF THE GENUS MUELLERIA FRENGUELLI

Navicula gibbula Cleve and its allies have a number of morphological characters which are visible under the light microscope and distinguish them from taxa included in Navicula Bory sensu stricto. These include proximal raphe ends which are sharply and unilaterally hooked and often extend beyond the central area, as well as two apparently thickened longitudinal ribs which extend the length of the valve on either side of the raphe. With the use of the SEM additional well-defined characters of the N. gibbula complex become apparent. Distal raphe ends are bifurcate and the valve face and mantle possess bipartite walls similar to those in Neidium Pfitzer. Furthermore, the apparently thickened longitudinal ribs are actually hollow canals, a feature reminiscent of the longitudinal canals of Diploneis Ehrenberg. Characters of the group are particularly well-defined and distinct from those of other genera, justifying separation from Navicula. Based on the valve morphology of N. gibbula and all other members of the section Naviculae fistulatae McCall, we separate these taxa from Navicula and resurrect the genus Muelleria Frenguelli to include them.

Reconstruction of a malformed external ear by an endoprosthesis of porous polyethylene with an integrated suction system

Complete reconstruction of the external ear is one of the most difficult tasks in plastic and reconstructive surgery. The risk of frame protrusion inherent in all alloplastic materials is reduced by using a new premoulded endoprosthesis with an integrated suction system. It consists of tissue-compatible porous polyethylene. A conventional suction drainage can be attached to a hollow canal system within the endoprosthesis that empties from defined spaces corresponding to the natural concavities of the external ear. In combination with a preceding expansion the overlying skin is then adapted evenly and completely to the frame by suction. As a result of this vacuum seromas and haematomas can be prevented. Furthermore, infections and pressure necroses due to matress sutures cannot develop. The use of this endoprosthesis obviates the removal of autogenous cartilage and all the complications and scars that are connected with this procedure. The frame itself is stable and has a relief that is largely similar to the natural form of the auricle. Thus, an aesthetically satisfying result can be achieved also in the hand of the surgeon who is not often engaged in this field of plastic surgery.