Spiral Ridges Research Articles

Hyperplastic conotruncal endocardial cushions and transposition of great arteries in perlecan-null mice.

Perlecan is a heparan-sulfate proteoglycan abundantly expressed in pericellular matrices and basement membranes during development. Inactivation of the perlecan gene in mice is lethal at two developmental stages: around E10 and around birth. We report a high incidence of malformations of the cardiac outflow tract in perlecan-deficient embryos. Complete transposition of great arteries was diagnosed in 11 out of 15 late embryos studied (73%). Three of these 11 embryos also showed malformations of semilunar valves. Mesenchymal cells in the outflow tract were abnormally abundant in mutant embryos by E9.5, when the endocardial-mesenchymal transformation starts in wild-type embryos. At E10.5, mutant embryos lacked well-defined spiral endocardial ridges, and the excess of mesenchymal cells obstructed sometimes the outflow tract lumen. Most of this anomalous mesenchyme expressed the smooth muscle cell-specific alpha-actin isoform, a marker of the neural crest in the outflow tract of the mouse. In wild-type embryos, perlecan is present in the basal surface of myocardium and endocardium, as well as surrounding presumptive neural crest cells. We suggest that the excess of mesenchyme at the earlier stages of conotruncal development precludes the formation of the spiral ridges and the rotation of the septation complex in order to achieve a concordant ventriculoarterial connection. The observed mesenchymal overpopulation might be due to an uncontrolled migration of neural crest cells, which would arrive prematurely to the heart. Thus, perlecan is involved in the control of the outflow tract mesenchymal population size, underscoring the importance of the extracellular matrix in cardiac morphogenesis.

Taxonomy, distribution, and characters of Pre-Oligocene members of theCantharusgroup of Pisaniinae (Neogastropoda: Buccinoidea)

This paper presents a review of Cretaceous to Eocene genera and species of theCantharusgroup of the buccinoidean neogastropod subfamily Pisaniinae, the description of two new genera and one new species, and a nonphylogenetic discussion of character evolution in this group. The new genusIckarusis introduced forTritonidea ickeiMartin, 1914, from the Nanggulan beds (middle Eocene) of Java, Indonesia.Editharus(type species:Fusus polygonusLamarck, 1803, middle Eocene of the Paris Basin, France) is a new genus with seven to nine species ranging from the early to late Eocene of Europe.Editharusis unusual in having a labral tooth formed at the angular junction between the adapical and abapical sectors of the outer lip.Editharus angulilabrisfrom the Marinesian (early late Eocene) is a new species from the Paris Basin closely related toE. polygonus.The incidence and expression of several characters has sharply increased in theCantharusgroup from the Paleogene to the Neogene. These characters include the presence of lirae (spiral ridges) on the inner side of the outer lip, the presence of a parietal tooth at the adapical end of the inner lip, and determinate growth (as inferred from a unique adult varix). These trends are also exhibited by other Cenozoic gastropod clades.

TAXONOMY, DISTRIBUTION, AND CHARACTERS OF PRE-OLIGOCENE MEMBERS OF THECANTHARUSGROUP OF PISANIINAE (NEOGASTROPODA: BUCCINOIDEA)

This paper presents a review of Cretaceous to Eocene genera and species of the Cantharus group of the buccinoidean neogastropod subfamily Pisaniinae, the description of two new genera and one new species, and a nonphylogenetic discussion of character evolution in this group. The new genus Ickarus is introduced for Tritonidea ickei Martin, 1914, from the Nanggulan beds (middle Eocene) of Java, Indonesia. Editharus (type species: Fusus polygonus Lamarck, 1803, middle Eocene of the Paris Basin, France) is a new genus with seven to nine species ranging from the early to late Eocene of Europe. Editharus is unusual in having a labral tooth formed at the angular junction between the adapical and abapical sectors of the outer lip. Editharus angulilabris from the Marinesian (early late Eocene) is a new species from the Paris Basin closely related to E. polygonus. The incidence and expression of several characters has sharply increased in the Cantharus group from the Paleogene to the Neogene. These characters include the presence of lirae (spiral ridges) on the inner side of the outer lip, the presence of a parietal tooth at the adapical end of the inner lip, and determinate growth (as inferred from a unique adult varix). These trends are also exhibited by other Cenozoic gastropod clades.

Evolution and development of gastropod larval shell morphology: experimental evidence for mechanical defense and repair

The structural diversity of gastropod veliger larvae offers an instructive counterpoint to the view of larval forms as conservative archetypes. Larval structure, function, and development are fine-tuned for survival in the plankton. Accordingly, the study of larval adaptation provides an important perspective for evolutionary-developmental biology as an integrated science. Patterns of breakage and repair in the field, as well as patterns of breakage in arranged encounters with zooplankton under laboratory conditions, are two powerful sources of data on the adaptive significance of morphological and microsculptural features of the gastropod larval shell. Shells of the planktonic veliger larvae of the caenogastropod Nassarius paupertus [GOULD] preserve multiple repaired breaks, attributed to unsuccessful zooplankton predators. In culture, larvae isolated from concentrated zooplankton samples rapidly repaired broken apertural margins and restored the "ideal" apertural form, in which an elaborate projection or "beak" covers the head of the swimming veliger. When individuals with repaired apertures were reintroduced to a concentrated mixture of potential zooplankton predators, the repaired margins were rapidly chipped and broken back. The projecting beak of the larval shell is the first line of mechanical defense, covering the larval head and mouth and potentially the most vulnerable part of the shell to breakage. Patterns of mechanical failure show that spiral ridges do reinforce the beak and retard breakage. The capacity for rapid shell repair and regeneration, and the evolution of features that resist or retard mechanical damage, may play a more prominent role than previously thought in enhancing the ability of larvae to survive in the plankton.

Structure and Secretion of the Graptolite Prosicula, and its Application for Biostratigraphical and Evolutionary Studies

Studies on graptolite taxonomy and phylogeny in recent years have placed great emphasis on the proximal development of the rhabdosome, particularly the presence or absence of a virgella and early thecal growth patterns. As the prosicula was the earliest part of the graptolite skeleton to be secreted, it may also reveal fundamental information about evolutionary relationships within the Graptoloidea. The prosiculae from a variety of Ordovician taxa ranging in age from Tremadoc to Caradoc have been examined using a combination of light microscopy, SEM and TEM. Parameters investigated include the overall morphology, transition into the nema, pattern of longitudinal ridges and spiral line. Taxa show a change from early Tremadoc graptoloids which have a low diaphragm, prominent spiral line and lack longitudinal ridges, through late Tremadoc and early Arenig taxa which have longitudinal cortical bandages or spiralled, paired longitudinal ridges, into later Arenig and Llanvirn forms which have simple longitudinal ridges and indistinct spiral line and diaphragm. With additional work at higher stratigraphical levels, graptolite prosiculae may prove to be useful biostratigraphically when more complete material is absent, such as in palynomorph preparations from subsurface studies.

Ultrastructural observations on the tendon sheath of the rat tail.

The ultrastructure of the tendon sheath of the rat tail was examined with scanning and transmission electron microscopes. The tendon sheath was divided into three layers: the visceral, parietal and fibrous layers. By scanning electron microscopy, the longitudinal shallow ridges approximately 7 microns wide were seen on the surface of the visceral layer. On the other hand, the spiral ridges approximately 20 microns wide running at an angle of 35 degrees to the longitudinal axis were exposed clearly on the inner surface of the parietal layer. Blood capillary networks were also observed on the surface of the parietal layer, especially in the specimens treated with HCl. The fibrous layer of the tendon sheath was characterized by a large number of collagen fibers in a woven arrangement. The inner surface of the fibrous layer showed spiral ridges similar to that of the parietal layer, suggesting that the ridges of parietal and fibrous layers were concerned with the arrangement of collagen fibers in the innermost region of the fibrous layer.

Polysialylated NCAM expression on endocardial cells of the chick primary atrial septum

Septation of the tubular heart to form the multi-chambered heart involves endocardial cell mesenchymal transformation at discrete sites. These sites include the crests of endocardial cushions at the atrioventricular junction, crests of the spiral ridges within the outflow tract, and the leading edge of the atrial septum. The factors involved in this multi-step inductive process appear to include the neural cell adhesion molecule (NCAM). The down-regulation of NCAM coincident with mesenchymal transformation has been documented at the atrioventricular cushion tissue. In view of the function-regulating properties of polysialylated NCAM (PSA-NCAM), we hypothesized that this form of NCAM would be playing a role during the dramatic changes in cell-cell interactions occurring in the endocardium at the leading edge of the primary atrial septum. Chicken hearts at stages during primary atrial septum development were fixed with paraformaldehyde and either immunofluorescently stained for the light microscope analysis or immunoperoxidase stained for ultrastructural analysis. A monoclonal antibody to an NCAM polypeptide epitope (5E) was used to detect all forms of NCAM, while a monoclonal to the polysialic acid (5A5) was used to detect that subset of NCAM which is highly polysialylated (PSA-NCAM). By light microscope level analysis, an increase in immunostaining for NCAM and the appearance of PSA-NCAM was detected on embryonic chicken endocardial cells at the leading edge of the growing atrial septum. The ultrastructural analysis revealed that there is also a change in the pattern of NCAM and PSA-NCAM from a polarized localization to a more ubiquitous distribution over the endocardial cell surface as these cells send out processes, form multiple layers, and sink or move into the underlying extracellular matrix. PSA-NCAM was also detected along cell appositions of cells within the matrix. Both NCAM and PSA-NCAM levels were reduced on cells deep within the matrix. These findings indicate that during primary atrial septation, PSA-NCAM may be deployed on endocardial epithelial cells in order to down-regulate cell-cell interactions and allow the detachment and migration of some of these cells into the underlying matrix. Anat. Rec. 247:71–84 © 1997 Wiley-Liss, Inc.

Polysialylated NCAM expression on endocardial cells of the chick primary atrial septum.

Septation of the tubular heart to form the multi-chambered heart involves endocardial cell mesenchymal transformation at discrete sites. These sites include the crests of endocardial cushions at the atrioventricular junction, crests of the spiral ridges within the outflow tract, and the leading edge of the atrial septum. The factors involved in this multi-step inductive process appear to include the neural cell adhesion molecule (NCAM). The down-regulation of NCAM coincident with mesenchymal transformation has been documented at the atrioventricular cushion tissue. In view of the function-regulation properties of polysialylated NCAM (PSA-NCAM), we hypothesized that this form of NCAM would be playing a role during the dramatic changes in cell-cell interactions occurring in the endocardium at the leading edge of the primary atrial septum. Chicken hearts at stages during primary atrial septum development were fixed with paraformaldehyde and either immunofluorescently stained for the light microscope analysis or immunoperoxidase stained for ultrastructural analysis. A monoclonal antibody to an NCAM polypeptide epitope (5E) was used to detect all forms of NCAM, while a monoclonal to the polysialic acid (5A5) was used to detect that subset of NCAM which is highly polysialylated (PSA-NCAM). By light microscope level analysis, an increase in immunostaining for NCAM and the appearance of PSA-NCAM was detected on embryonic chicken endocardial cells at the leading edge of the growing atrial septum. The ultrastructural analysis revealed that there is also a change in the pattern of NCAM and PSA-NCAM from a polarized localization to a more ubiquitous distribution over the endocardial cell surface as these cells send out processes, form multiple layers, and sink or move into the underlying extracellular matrix. PSA-NCAM was also detected along cell appositions of cells within the matrix. Both NCAM and PSA-NCAM levels were reduced on cells deep within the matrix. These findings indicate that during primary atrial septation, PSA-NCAM may be deployed on endocardial epithelial cells in order to down-regulate cell-cell interactions and allow the detachment and migration of some of these cells into the underlying matrix.

Middle Ordovician carrier shellLytospira(Mollusca, Gastropoda) from Alaska

The euomphalacean gastropodLytospira gerulusn. sp. is described from the Middle Ordovician of west-central Alaska. The species is among the oldest known carrier shell specimens, and also shows evidence of repaired shell breakage; the breakage may have been the result of unsuccessful predation attempts. The interior of the shell shows an unusual spiral groove and ridges that may have been associated with the animal's retractor muscle. This internal groove may be an overlooked feature of all species ofLytospira.

Finite element analysis of a double membrane tube (DMS-tube) and its implication for gastropod shell morphology.

Molluscan shells, including those of Gastropoda, are formed by accretionary growth at the mantle edge. The mantle is a thin membrane of skirt-like shape, which extends minutely beyond the aperture, and its edge adds a shell increment to the aperture margin so that each increment copies a configuration of the mantle edge at that time. Thus, regulation of shell morphogeny is almost equivalent to the factors which control the mantle form at the moment of shell growth. Form of the mantle skirt is considered to be kept in a state of balance between the force of its internal stress and forces acting on it such as fluid pressure or muscle contraction. The expansion behavior of the mantle skirt has been numerically analyzed by using an elastic model (DMS-tube), which represents the fundamental structure of the mantle tissue as a double membrane structure with internal springs (DMS). Four characteristic expansion patterns of the DMS-tube have been detected: (1) general outward expansion; (2) developing a ridge-like fold on an initial longitudinal protrusion of the tube edge; (3) drastic shift of the expanded state from a uniformly curved to an elliptical shape in outline, owing to the existence of a fixed boundary condition on the tube wall; and (4) constricted protrusion on the open region of the shell wall surrounding the DMS-tube. These results have the potential for answering the following questions relating to the morphogenesis of gastropod shells. How does the mantle skirt usually make contact with the inner surface of the shell wall so as to ensure continuous accretion of shell materials to the aperture margin? What is the cause of spiral ridges? Why do open coiling or minimally overlapping shells have generally circular apertures, while shells with apertures overlapped by whorls have non-uniformly curved apertural lips? What is the cause of long closed spines and why do they always appear on spiral ridges?

Ribosome binding sites visualized on freeze-fractured membranes of the rough endoplasmic reticulum.

Freeze-fracture micrographs of cells of the green alga Micrasterias denticulata stabilized by ultrarapid freezing reveal imprints of polysomes on the rough endoplasmic reticulum membranes. The imprints appear as broad, spiral ridges on the P faces and as corresponding wide grooves on the E faces of the membranes. Distinct 110-A particles with a spacing of 270 +/- 45 A are associated with the P-face ridges. Where imprints of individual ribosomes can be discerned, it is seen that there is a 1:1 relationship between the ribosomes and the 110-A particles, and that the 110-A particles are located in a peripheral position with respect to the polysome spirals. We propose that the 110-A particles could be structural equivalents of ribosome-binding sites, consisting of a molecule each of ribophorins I and II and a nascent polypeptide chain. These observations suggest that the spiral form of polysomes could result from the forces generated by the extrusion of the growing polypeptide chains to one side of the polysome.

An unusual cell surface modification: A double plasma membrane

The occurrence of an unusual double plasma membrane structure is reported; it has been studied in conventional thin sections, after lanthanum-impregnation and with freeze-fracturing. This modification of the plasmalemma is found where the luminal cell membrane (I membrane) of gut microvilli in the haematophagous insect, Rhodnius prolixus, is surrounded by a second, outer membrane (O membrane), the 2 separated from one another by a highly regular I-O space of about 10 nm. Lanthanum impregnation reveals the presence of columns inclined at an angle, within this I-O space; as in the continuous junctions which link the lateral borders of these cells, these columns may maintain the very precise I-O distance. From the outer microvillar membranes radiate short spoke-like fibrils or sheets which encounter another more extensive system of myelin-like sheets. Freeze-fracturing reveals that the spoke-like sheets and the other ones which lie like a tube, around and parallel to the microvilli, contain linear ridges composed of particles, lying at random within layers of the myelin-like material which also extends into the lumen of the gut. The microvillar membanes, both O and I, fracture into faces containing rows of either PF particles or EF pits arranged as spiral ridges or grooves around the sides and across the tip of each microbillus. These could be the insertion sites of one or both of the I-O columns and spoke-like sheets while the sheets could represent a variant of peritrophic membrane. The double membrane may be a cellular device to increase the strength of the microvillar layer in these blood-sucking animals, since the cell layer must withstand great pressure owing to a sudden massive extension of the gut during a blood meal.

Role of the left interventricular sulcus in formation of interventricular septum and crista supraventricularis in normal human cardiogenesis.

Serial sections of normal human embryos were studied and three-dimensional images reconstructed to determine the early development of the interventricular septum. The position of the interventricular septum is determined in stage 9 of normal development by the formation of the left interventricular sulcus. As a result of unknown properties of the cells of the myocardial layer, the left interventricular sulcus persists while the right disappears, producing the initial lateral asymmetry of the primary heart tube. By stage 14, the left interventricular sulcus forms a spiral which is continuous with the developing interventricular septum. The dorsal limb of the spiral passes to the right between the atrioventricular canal and the origin of the outflow tract, and is lost in the wall of the trabeculated right ventricle. It appears that this dorsal limb of the spiral is the precursor of part of the cirsta supraventricularis. The midportion of the sulcus, the bulboventricular groove, becomes the so-called fibrous continuity between the aortic and mitral valves. The ventral limb of the spiral passes caudally in the anterior interventricular groove and then dorsally and cranially toward the dorsal cushion of the atrioventricular canal. The ventral limb of the spiral is continuous with the crest of the muscular interventricular septum, which develops by apposition of tissue from the expanding right and left ventricles. From stage 14 to stage 19, the muscular interventricular septum, the atrioventricular endocardial cushions, and the ventricular end of the spiral ridges of the outflow tract appose and fuse. Subsequent formation of the membranous interventricular septum completes the physical separation of the right and left ventricles.

Modification of the Cuticle and Primary Wall of Cotton by Corona Treatment

Transmission electron microscope studies of the surface of air-corona and air-chlorine corona treated cotton fibers reveal essentially no topographical changes. Air-chlorine coronas apparently modify the wax, causing increased wettability, and C-chlorination occurs in about one of every three carbon atoms in the cuticle. About one half of the chlorine that reacts with cotton is covalently bonded to carbon in the wax, the remainder to nonextractable constituents of the cuticle or the primary wall. The secondary wall remains essentially unchanged by corona treatment as indicated by tenacity, crystallinity, solubility in cupriethylenediamine hydroxide, iodine uptake, and moisture regain (the latter may be marginally decreased). Increased accessibility of the fiber interior or secondary wall component to swelling reagents such as caustic, and yarn setting reagents such as benzyltrimethylammonium hydroxide, indicates that corona treatments modify the surface layer or primary wall in such a way as to weaken it and possibly to increase its permeability. However, marginally diminished regain and unchanged iodine sorption values do not support such conclusions. Corona treated cotton exposed to an electron beam develops cracks several thousands of angstroms deep, parallel to the spiral ridges— further evidence of a weakened surface layer. Potential practical applications of corona treatmemt are indicated by improved mercerization, better yarn stretch and setting properties, increased dyeability, and the localized heating indicated by the generation of free radicals which may make possible heat-induced localized polymerization.

The development of the arterial outflow tract in the chick embryo heart

AbstractBloodstream flow patterns have been outlined in the arterial outflow tract (ventricular outflow tract and bulbus arteriosus) of the chick embryo heart during the period in which septation takes place, Hemodynamic factors underlying flow changes during this period are discussed.The mapping of flow patterns did not support the concept of a conoventricular flange reported previously. Septation was found to take place between two separate and discrete bloodstreams.The cellular nature of the aorticopulmonary septum has been described. The spiral ridges that form this septum expand by cellular growth, explaining the ability of this septum to develop against the direction of blood flow. The aorticopulmonary septum divides about two‐thirds of the arterial outflow tract; the final partitioning of the most proximal portion of the outflow tract was found to take place by means of the apposition of endocardial cushion tissue masses.Failure of aorticopulmonary septum development (truncus arteriosus communis persistens) was found to follow fusion of the bloodstreams in experimental studies. In experimental aortic stenosis the appearance of a small left stream was found to be followed by the development of a stenotic aorta. Thus in the first instance the septum apparently cannot develop unless the streams remain separate and in the second case the size of the prhnordial bloodstreams appears to determine the diameter of the vessel.

Arabiens arkæologi

Arabiens arkæologi

On the Theory of the Progressive Universal Winding

The rigorous theory previously developed by the author for the ordinary or stationary universal winding is extended to the progressive universal winding; in particular, an exact formula for calculating the gear ratio to be employed in winding a progressive universal coil is deduced, and, by neglecting certain terms therein, formulas representing various degrees of approximation of the same are derived and shown to be equivalent of those previously given by the author, by Joyner and Landon, and by Hershey. The theory of the spiral ridges and close-packed layers of progressive universal coils is developed, and formulas giving the slope of the spiral ridge and the dimensions of the close-packed layers are deduced. The principles underlying the selection of the optimum number of crossovers per turn are discussed, and an example of the application of the formulas to the design of a progressive universal coil is given.

The Cretaceous Shales of Jamaica

A well preserved specimen 46mm. long and 22·5mm. wide (Fig.17) was found by Mr. R. Cory near Catadupa. The body whorl is contracted below the suture and has ten varices which die away at the anterior contraction and are slightly acute at the shoulder; the anterior part of the shell has five wavy spiral ridges. A smaller and more delicate but poorly preserved form (Fig. 18), with similar but more anteriorly produced varices, occurs just above the Barrettia limestone at St. Ann's Great River and resembles specimens of L. crassicostata Stol. from Assam figured by Spengler (Pal. Ind., N. Series, vol. viii, mem. i, 1923, pl. iii, figs. 34a, and b). Another species of Lyria or Volutilites (Fig. 16) with elongated spire has about 7 coarse uneven varices on the body whorl and occurs as badly preserved casts in the Providence shales. It attains a length of 47 mm.

The evolution of the shell-sculpture in fresh-water snails of the family Viviparidæ

The peculiar sculptured shells of the Viviparidæ of Pliocene lake-basins in the old Austrian Empire and the Greek Archipelago have been discussed at length by several authors, notably in the first instance by Edward Forbes, and later by Brusina, by Tournouër, by Neumayr and by Newton. These authors have established the fact that in Slavonia and Dalmatia and in the island of Cos shells of the family ornamented with prominent spiral ridges gradually replaced those with a smooth surface in the course of the Pliocene age, while in the same countries the ridge shells have now disappeared and the Viviparidæ again have smooth shells. Neumayr has compared the Pliocene species with Nevill’s genus Margarya from Yunnan and (with greater justice in my opinion) with Tulotoma Haldeman from North America. We possess details of the ancestry not only in the European and Levantine forms but also of that of Margarya in Western China and of that of a very similar genus recently described by myself under the name Taia from the Shan plateau of Upper Burma. Of these three series we have details of the living forms and of the types of environment they inhabit or inhabited only in Taia , fresh observations on which are given below. If we compare the majority of the shells of the European and Levantine ridge-shelled Viviparidæ with those of either of the two eastern genera a very close resemblance in the general character of the sculpture is at first sight the most salient feature, but a closer examination reveals (with other minor points which it is unnecessary to mention here) an almost constant difference in the number of ridges on each shell ( cf . figs. 3, 4 and 6). In the Pliocene European forms there are rarely more than two spiral ridges on the body-whorl; whereas in sculptured shells of either Taia or Margarya there are almost always three main ridges and as a rule several subsidiary ridges, and one of the main ridges, that on the periphery of the whorl, is often much the most prominent. This does not seem an important difference if adult shells only are examined; but if we consider the soft parts of the living forms in correlation with the structure of the shell and compare the embryonic shell, it is seen to imply a constant anatomical difference.