bluuebunny/crossref_metadata_2025 huggingface dataset:
Feature Preserving Mesh Generation from 3D Point Clouds
Authors: Salman Nader , Yvinec Mariette , Merigot Quentin
Published: September 2010

We address the problem of generating quality surface triangle meshes from 3D point clouds sampled on piecewise smooth surfaces. Using a feature detection process based on the covariance matrices of Voronoi cells, we first extract from the point cloud a set of sharp features. Our algorithm also runs on the input point cloud a reconstruction process, such as Poisson reconstruction, providing an implicit surface. A feature preserving variant of a Delaunay refinement process is then used to generate a mesh approximating the implicit surface and containing a faithful representation of the extracted sharp edges. Such a mesh provides an enhanced trade‐off between accuracy and mesh complexity. The whole process is robust to noise and made versatile through a small set of parameters which govern the mesh sizing, approximation error and shape of the elements. We demonstrate the effectiveness of our method on a variety of models including laser scanned datasets ranging from indoor to outdoor scenes.
High Fidelity Scan Merging
Authors: Digne J. , Morel J.‐M. , Audfray N. , Lartigue C.
Published: September 2010

For each scanned object 3D triangulation laser scanners deliver multiple sweeps corresponding to multiple laser motions and orientations. The problem of aligning these scans has been well solved by using rigid and, more recently, non‐rigid transformations. Nevertheless, there are always residual local offsets between scans which forbid a direct merging of the scans, and force to some preliminary smoothing. Indeed, the tiling and aliasing effects due to the tiniest normal displacements of the scans can be dramatic. This paper proposes a general method to tackle this problem. The algorithm decomposes each scan into its high and low frequency components and fuses the low frequencies while keeping intact the high frequency content. It produces a mesh with the highest attainable resolution, having for vertices all raw data points of all scans. This exhaustive fusion of scans maintains the finest texture details. The method is illustrated on several high resolution scans of archeological objects.
Scales and Scale‐like Structures
Authors: Landreneau Eric , Schaefer Scott
Published: September 2010

We present a method for generating scales and scale‐like structures on a polygonal mesh through surface replacement. As input, we require a triangular mesh that will be covered with scales and one or more proxy‐models to be used as the scale's shape. A user begins scale generation by drawing a lateral line on the model to control the distribution and orientation of scales on the surface. We then create a vector field over the surface to control an anisotropic Voronoi tessellation, which represents the region occupied by each scale. Next we replace these regions by cutting the proxy model to match the boundary of the Voronoi region and deform the cut model onto the surface. The result is a fully connected 2‐manifold that is suitable for subsequent post‐processing applications like surface subdivision.
Designing Quad‐dominant Meshes with Planar Faces
Authors: Zadravec Mirko , Schiftner Alexander , Wallner Johannes
Published: September 2010

We study the combined problem of approximating a surface by a quad mesh (or quad‐dominant mesh) which on the one hand has planar faces, and which on the other hand is aesthetically pleasing and has evenly spaced vertices. This work is motivated by applications in freeform architecture and leads to a discussion of fields of conjugate directions in surfaces, their singularities and indices, their optimization and their interactive modeling. The actual meshing is performed by means of a level set method which is capable of handling combinatorial singularities, and which can deal with planarity, smoothness, and spacing issues.
Closed‐form Blending of Local Symmetries
Authors: Ghosh Deboshmita , Amenta Nina , Kazhdan Michael
Published: September 2010

We present a closed‐form solution for the symmetrization problem, solving for the optimal deformation that reconciles a set of local bilateral symmetries. Given as input a set of point‐pairs which should be symmetric, we first compute for each local neighborhood a transformation which would produce an approximate bilateral symmetry. We then solve for a single global symmetry which includes all of these local symmetries, while minimizing the deformation within each local neighborhood. Our main motivation is the symmetrization of digitized fossils, which are often deformed by a combination of compression and bending. In addition, we use the technique to symmetrize articulated models.
Multi‐scale Geometric Modeling of Ambiguous Shapes with : oleranced Balls and Compoundly Weighted α‐shapes
Authors: Cazals Frédéric , Dreyfus Tom
Published: September 2010

Dealing with ambiguous data is a challenge in Science in general and geometry processing in particular. One route of choice to extract information from such data consists of replacing the ambiguous input by a continuum, typically a one‐parameter family, so as to mine stable geometric and topological features within this family. This work follows this spirit and introduces a novel framework to handle 3D ambiguous geometric data which are naturally modeled by balls.

First, we introduce toleranced balls to model ambiguous geometric objects. A toleranced ball consists of two concentric balls, and interpolating between their radii provides a way to explore a range of possible geometries. We propose to model an ambiguous shape by a collection of toleranced balls, and show that the aforementioned radius interpolation is tantamount to the growth process associated with an additively‐multiplicatively weighted Voronoi diagram (also called compoundly weighted or CW). Second and third, we investigate properties of the CW diagram and the associated CW α‐complex, which provides a filtration called the λ‐complex. Fourth, we sketch a naive algorithm to compute the CW VD. Finally, we use the λ‐complex to assess the quality of models of large protein assemblies, as these models inherently feature ambiguities.
THE SWEDISH PAST PARTICIPLE: SOME ARGUMENTS FOR A LEXICAL REDUNDANCY RULE
Authors: Platzack Christer
Published: September 2010

In this paper, I have tried to give a description of the Swedish past participle which accounts for both the adjectival and the verbal character of this category. The past participle of a verb is envisaged as forming a lexical entry of its own, related to the lexical entry of the verb with the help of a lexical redundancy rule. To account for the various syntactic similarities between past participles and adjectives, the lexical entry of the past participle is marked + ADJ. The differences between an adjective and a past participle are claimed to be exclusively semantic. The crucial difference seems to be that the past participle focuses on the act referred to by the verb, whereas the adjective just denotes a state of affairs. To obtain the ‘verbal’ meaning of the past participle, I have proposed a description where the meaning of the verb functions as a restrictive modifier of the central meaning of the participle. Furthermore, I have claimed that this central meaning can always be inferred from the meaning of the verb. In section 3 of the paper, I give several arguments for a semantic description of the past participle.
THE REANALYSIS OF GRAMMATICALIZED PREPOSITIONS IN MIDDLE ENGLISH
Authors: van Gelderen Elly
Published: September 2010

Abstract. During the Middle English period, a number of prepositions grammaticalize. I examine three of these (namely for(to), to and on) and argue that they come to be associatmwith verbal features as well as future, tense and aspect. As this happens, they change their structural positions and are reanalyzed as C(omplementizer), I(inflection) and ASP(ect) respectively. The latter categories are assumed by the language user as a response to the affiliation of the verbal features of for(to), to and on.
IDIOMATICITY AND TERMINOLOGY: A MULTI‐DIMENSIONAL DESCRIPTIVE MODEL
Authors: Barkema Henk
Published: September 2010

Abstract.In this article we discuss the traditional terminology for idioms and other lexicalised expressions. We claim that it is inadequate for accurate, explicit and detailed descriptions of the various linguistic characteristics of expressions. As an alternative, we introduce a well‐defined model with which three different types of linguistic characteristics can be captured with a small set of labels: composition‐ality, collocability and flexibility. What is new in our approach is that asetof labels is given to one expression instead of only one label. Each of these either indicates how the expression scores on a given scale or indicates additional characteristics of the expression (e.g. idiosyncratic syntax). In an appendix we provide an inventory of terms discussed in this article, with their definitions.
MOTION AND EXTENT: TWO SIDES OF THE SAME COIN
Authors: Iwata Seizi
Published: September 2010

Abstract. This paper examines the relationship between a motion sentence (e.g, Amy went from Denver to Indianapolis.) and an extent sentence (e.g., The road goes from Denver to Indianapolis.), building upon Jackendoft's (1983) analysis. It is shown that the semantic functions for motion and extent senses, respectively GO and GOExl, are distinct, but that they share a great deal of internal structure. While both functions express successive transition from one component state to the next, they differ in (a) the presence vs. absence of the passage of time, and (b) the identity of the mover through transition.

The analysis presented here based on semantic functions comes closer to an overall characterization of the motion/extent contrast than the image‐schema‐based approach (Lakoff 1987) or the metaphor‐based approach (Lakoff & Turner 1989). It can also be easily extended to account for types of extent sentences that the literature has not focussed upon.
Is Compositionality Compatible with Holism?
Authors: PAGIN PETER
Published: September 2010

Abstract: This paper deals with three prima facie problems for the compatibility of the principle of semantic compositionality with semantic holism. The first problem concerns the order and mode of determination of the meaning of complex expressions. The second concerns the individuation of meanings, and, as a consequence, the possibility of communication. The third problem concerns the role of compositionality in explaining the understanding of new sentences, and, in conjunction with that, the possibility of language learning. It is argued that each has an acceptable solution.
Explaining Systematicity
Authors: AIZAWA KENNETH
Published: September 2010

Abstract: Despite the considerable attention that the systematicity argument has enjoyed, it is worthwhile examining the argument within the context of similar explanatory arguments from the history of science. This kind of analysis helps show that Connectionism, qua Connectionism, really does not have an explanation of systematicity. Second, and more surprisingly, one finds that the systematicity argument sets such a high explanatory standard that not even Classicism can explain the systematicity of thought.
Can Connectionists Explain Systematicity?
Authors: MATTHEWS ROBERT J.
Published: September 2010

Abstract: Classicists and connectionists alike claim to be able to explain systematicity. The proposed classicist explanation, I argue, is little more than a promissory note, one that classicists have no idea how to redeem. Smolensky's (1995) proposed connectionist explanation fares little better: it is not vulnerable to recent classicist objections, but it nonetheless fails, particularly if one requires, as some classicists do, that explanations of systematicity take the form of a‘functional analysis’. Nonetheless, there are, I argue, reasons for cautious optimism about the prospects of a connectionist explanation.
Representing Space in Language and Perception
Authors: BRYANT DAVID J.
Published: September 2010

Abstract: Space can be understood through perception and language, but are the processes that represent spatial information the same in both cases? This paper reviews psychological evidence for the functional equivalence of spatial representations based on perceptual and linguistic inputs. It is proposed that spatial information is processed by a specialised spatial representation system (SRS) that creates geometric representations of space. The SRS receives inputs from perceptual and linguistic systems and uses these basic inputs to construct mental spatial models of the observed or described environment. A mental spatial model is created by determining the coordinate locations of objects in the egocentric or allocentric frame of reference. The goal of the SRS is not to represent strictly what is perceived, but to model an environment that has an inherent three‐dimensional spatial structure.
Cognitive Penetrability, Rationality and Restricted Simulation
Authors: STICH STEPHEN , NICHOLS SHAUN
Published: September 2010

Abstract: Heal (1996a) maintains that evidence of cognitive penetrability doesn't determine whether stimulation theory or theory theory wins. Given the wide variety of mechanisms and processes that get called ‘simulation’, we argue that it's not useful to ask‘who wins?’. The label ‘simulation’picks out no natural or theoretically interesting category. We propose a more fine‐grained taxonomy and argue that some processes that have been labelled ‘simulation’, eg.,‘actual‐situation‐simulation’, clearly do exist, while other processes labelled ‘simulation’, e.g., ‘pretence‐driven‐off‐line‐simulation’are quite controversial. We do concede that evidence of cognitive penetrability isn't decisive evidence against pretence‐driven‐off‐line‐simulation. Nonetheless, advocates of pretence‐driven‐off‐line‐simulation need to provide some explanation of the experimental evidence of penetrability. We argue that Heal's suggestion that simulation is restricted to‘rational’processes is unprincipled, and we offer an alternative proposal for restricted simulation.
Delusions and Brain Injury: The Philosophy and Psychology of Belief
Authors: STONE TONY , YOUNG ANDREW W.
Published: September 2010

Abstract: Circumscribed delusional beliefs can follow brain injury. We suggest that these involve anomalous perceptual experiences created by a deficit to the person's perceptual system, and misinterpretation of these experiences due to biased reasoning. We use the Capgras delusion (the claim that one or more of one's close relatives has been replaced by an exact replica or impostor) to illustrate this argument. Our account maintains that people voicing this delusion suffer an impairment that leads to faces being perceived as drained of their normal affective significance, and an additional reasoning bias that leads them to put greater weight on forming beliefs that are observationally adequate rather than beliefs that are a conservative extension of their existing stock. We show how this position can integrate issues involved in the philosophy and psychology of belief, and examine the scope for mutually beneficial interaction.
Against Darwinism
Authors: FODOR JERRY
Published: September 2010

Abstract: Darwinism consists of two parts: a phylogenesis of biological species (ours included) and the claim that the primary mechanism of the evolution of phenotypes is natural selection. I assume that Darwin’s account of phylogeny is essentially correct; attention is directed to the theory of natural selection. I claim that Darwin’s account of evolution by natural selection cannot be sustained. The basic problem is that, according to the consensus view, evolution consists in changes of the distribution of phenotypic traits in populations of organisms. An evolutionary theory must therefore explicate not just the notion of organisms being selected, but also the notion of organisms being selected for their phenotypic traits. I argue that that there is no way for a theory of natural selection to do so, and that Darwin’s assumption to the contrary was likely the consequence of placing too much weight on the analogy between natural selection and artificial selection. The paper ends with the suggestion that selectionist explanations, insofar as they are convincing, are best construed aspost hochistorical narratives: natural history rather than biology.
Intention, Temporal Order, and Moral Judgments
Authors: SINNOTT‐ARMSTRONG WALTER , MALLON RON , McCOY TOM , HULL JAY G.
Published: September 2010

Abstract:  The traditional philosophical doctrine of double effect claims that agents’ intentions affect whether acts are morally wrong. Our behavioral study reveals that agents’ intentions do affect whether acts are judged morally wrong, whereas the temporal order of good and bad effects affects whether acts are classified as killings. This finding suggests that the moral judgments are not based on the classifications. Our results also undermine recent claims that prior moral judgments determine whether agents are seen as causing effects intentionally rather than as side effects.
Demonstrative Thought
Authors: LEVINE JOSEPH
Published: September 2010

In this paper I propose a model of demonstrative thought. I distinguish token‐demonstratives, that pick out individuals, from type‐demonstratives, that pick out kinds, or properties, and provide a similar treatment for both. I argue that it follows from my model of demonstrative thought, as well as from independent considerations, that demonstration, as a mental act, operates directly on mental representations, not external objects. That is, though the relation between a demonstrative and the object or property demonstrated is semantically direct, the mechanism by which a demonstrative acquires its referent involves mediation by a perceptual representation. Finally, I argue that so‐called ‘demonstrative concepts'—which I treat as type‐demonstratives—cannot perform the various philosophical functions that have been assigned to them.
Expectations Without Content
Authors: LUNTLEY MICHAEL
Published: September 2010

In this paper I show how the way experience presents things to us can be treated without attributing a representational content to experience. The basic claim that experience can present us with more things than the range of things available to us in thought is neutral with respect to the choice between a content account of experience and a naïve content‐free account. I show how Meyer's theory of expectations in accounting for our experience of music supports the naïve account. Expectations provide an account of the conditions that enable things to be salient in experience as targets for attention. Expectations do not provide a content to experience.
The Potential and Precariousness of Partnership: The Case of the Kaiser Permanente Labor Management Partnership
Authors: KOCHAN THOMAS A. , ADLER PAUL S. , MCKERSIE ROBERT B. , EATON ADRIENNE E. , SEGAL PHYLLIS , GERHART PAUL
Published: September 2010

In 1997, the Kaiser Foundation Health Care and Hospitals, the Permanente Medical Federation, and a coalition of unions signed a national agreement creating one of the most ambitious labor management partnerships in U.S. history, initially covering some 58,000 employees. Based on field research and archival data, this paper analyzes the first eight years of this partnership in light of three strategic challenges—initiating, governing, and sustaining partnership—and the organizational challenge of partnership in a highly decentralized organization.
An Individual‐Level Study of Contract Ratification Support
Authors: MARTIN JAMES E.
Published: September 2010

This study uses constructs developed from theoretical models of both unit‐level ratification studies and individual‐level studies of strike support to predict individual employee ratification voting behavior and contract satisfaction. Surveys were given to union members before and after ratification voting. The results suggest that constructs assessing economic factors, employment relations, union relations, and the importance of contract information from the union all influence ratification support. While the bargaining issues are important in explaining ratification support, factors beyond the bargaining issues, such as employer and union loyalty and providing information about the contract, are related to ratification support.
Unions and Wages in Australia: Does Employer Size Matter?
Authors: WADDOUPS C. JEFFREY
Published: September 2010

Industrial relations reforms starting in the late 1980s decentralized wage determination in Australia. Using data from the Australian Bureau of Statistics’ Survey of Education and Training gathered in 1993, before the full effects of decentralization had been realized, and in 2001, after which the impacts of structural changes had become manifested, the study shows the emergence of an inverse relationship between the employer size–wage effect and union/nonunion wage differential among male workers. The relationship is similar to those found in the United States and the UK, other economies with decentralized wage‐setting regimes.
High‐Performance Work System and Organizational Turnover in East and Southeast Asian Countries1
Authors: YALABIK ZEYNEP Y. , CHEN SHYH‐JER , LAWLER JOHN , KIM KWANGHYUN
Published: September 2010

In this paper, we examine the impact of high‐performance work systems (HPWSs) on both voluntary and involuntary organizational turnover rates. Most research on this topic has been done in the United States. Given the global competitive pressures confronting many of the countries of East and Southeast Asia, companies in this region are seeking to become more flexible and often adapt HPWSs practices. We explore the impact of HPWSs in both locally owned companies and subsidiaries of multinational corporations in Korea, Taiwan, Singapore, and Thailand. These countries have significantly different national cultures from the United States and most other Western countries and HPWSs effects in relation to turnover might vary from the studies based in the United States. Our findings are, however, somewhat consistent with U.S.‐based studies. In fact, HPWSs were found to be more effective in reducing turnover in locally owned companies than in subsidiaries of Western and Japanese multinational companies.
Mandatory Retirement and Faculty Retirement Decisions
Authors: CLARK ROBERT L. , GHENT LINDA S.
Published: September 2010

As a result of the 1986 Age Discrimination in Employment Act, colleges and universities were no longer allowed to impose mandatory retirement on faculty members at age seventy after 1994. This paper estimates the change in retirement rates of faculty before and after the ending of mandatory retirement using data from the University of North Carolina (UNC) system. The analysis reveals a sharp decline in the probability of faculty at UNC retiring at age seventy once the university was unable to impose forced retirement.
God in America: Why Theology Is Not Simply the Concern of Philosophers
Authors: FROESE PAUL , BADER CHRISTOPHER D.
Published: September 2010

As citizens of the most technologically advanced and economically developed country in the world, nearly all Americans stalwartly maintain their faith in God, much more so than residents of other postindustrial countries (Norris and Ingelhart 2004). But what is the content and meaning of this belief? Perhaps belief in God has become so pervasive in contemporary American culture that it reflects little about believers' deeper religious thoughts, identities, and actions. We find the opposite to be true. Outside the confines of seminaries, competing beliefs about who God is and what God wants have a clear and important connection to everyday religious life in the United States. Subtle distinctions in American images of God powerfully predict religious diversity as measured by belief in the truth of a single religious faith, religious devotion, and attitudes about the compatibility of secular and religious spheres. More specifically, we discern that American religious conservatism, in all its forms, can be aptly characterized by the belief that God is highly engaged in the world and particularly judgmental of human behavior.
Social Involvement in Religious Institutions and God‐Mediated Control Beliefs: A Longitudinal Investigation
Authors: KRAUSE NEAL M.
Published: September 2010

This study examines the relationships among race, education, formal as well as informal involvement in the church, and God‐mediated control. Formal involvement in the church was assessed by the frequency of attendance at worship services, Bible study groups, and prayer groups. Informal involvement was measured with an index of spiritual support provided by fellow church members. Data from a nationwide longitudinal survey of older people suggest that both formal and informal church involvement tend to sustain feelings of God‐mediated control over time. The findings further reveal that compared to older whites, older African Americans are more likely to have stronger feelings of God‐mediated control at the baseline survey and older blacks are more likely to sustain their sense of God‐mediated control over time. In contrast, the data suggest that education is not significantly related to feelings of God‐mediated control.
Experimental Evidence that Theistic‐Religious Body Affirmations Improve Women's Body Image
Authors: BOYATZIS CHRIS J. , KLINE SARAH , BACKOF STEPHANIE
Published: September 2010

We examined in a random‐assignment, pretest‐posttest design whether college women's body image would improve after reading religious and spiritual affirmations about their bodies. The sample was predominantly white and Christian. In a pretest, women completed measures of religiosity and body esteem (how they felt about their weight and appearance) and were then assigned via matched random assignment to three different groups for a treatment and posttest one week later. In the Religious group, women read affirmations with a theistic and Christian‐based tone that emphasized God's love and acceptance of their bodies; in the Spiritual group, women read body affirmations with a more positive secular tone and no mention of God; Control group women read random statements about campus issues. After reading the affirmations, women then viewed photos of “thin ideal” fashion models to activate body image concerns. Women next completed the posttest body esteem measures. Women in the Religious group increased significantly compared to Control women (who declined) in how they felt about their appearance and looks. Women in the Spiritual condition improved marginally compared to the Control condition.
Class and Congregations: Class and Religious Affiliation at the Congregational Level of Analysis
Authors: REIMER SAM
Published: September 2010

Since Niebuhr's seminal work on the social sources of denominationalism, nearly all research on the relationship between social class and religious affiliation has focused on the denominational (or individual) level of analysis. This research examines the effects of social class at the congregational level—effects that were previously glossed over by a unit of analysis that was too large. After demonstrating the relative strength of social class at the denominational and congregational level, I argue that our theoretical attempts to link class and religious affiliation must include congregational‐level explanations.
Morphological analysis of the hindlimb in apes and humans. I. Muscle architecture
Authors: Payne R. C. , Crompton R. H. , Isler K. , Savage R. , Vereecke E. E. , Günther M. M. , Thorpe S. K. S. , D’Août K.
Published: September 2010

We present quantitative data on the hindlimb musculature ofPan paniscus,Gorilla gorilla gorilla,Gorilla gorilla graueri,Pongo pygmaeus abelii and Hylobates larand discuss the findings in relation to the locomotor habits of each. Muscle mass and fascicle length data were obtained for all major hindlimb muscles. Physiological cross‐sectional area (PCSA) was estimated. Data were normalized assuming geometric similarity to allow for comparison of animals of different size/species. Muscle mass scaled closely to (body mass)1.0and fascicle length scaled closely to (body mass)0.3in most species. However, human hindlimb muscles were heavy and had short fascicles per unit body mass when compared with non‐human apes. Gibbon hindlimb anatomy shared some features with human hindlimbs that were not observed in the non‐human great apes: limb circumferences tapered from proximal‐to‐distal, fascicle lengths were short per unit body mass and tendons were relatively long. Non‐human great ape hindlimb muscles were, by contrast, characterized by long fascicles arranged in parallel, with little/no tendon of insertion. Such an arrangement of muscle architecture would be useful for locomotion in a three dimensionally complex arboreal environment.
The role of the endoderm in the development and evolution of the pharyngeal arches
Authors: Graham Anthony , Okabe Masataka , Quinlan Robyn
Published: September 2010

The oro‐pharyngeal apparatus has its origin in a series of bulges found on the lateral surface of the embryonic head, the pharyngeal arches. Significantly, the development of these structures is extremely complex, involving interactions between a number of disparate embryonic cell types: ectoderm, endoderm, mesoderm and neural crest, each of which generates particular components of the arches, and whose development must be co‐ordinated to generate the functional adult oro‐pharyngeal apparatus. In the past most studies have emphasized the role played by the neural crest, which generates the skeletal elements of the arches, in directing pharyngeal arch development. However, it is now apparent that the pharyngeal endoderm plays an important role in directing arch development. Here we discuss the role of the pharyngeal endoderm in organizing the development of the pharyngeal arches, and the mechanisms that act to pattern the endoderm itself and those which direct its morphogenesis. Finally, we discuss the importance of modification to the pharyngeal endoderm during vertebrate evolution. In particular, we focus on the emergence of the parathyroid gland, which we have recently shown to be the result of the internalization of the gills.
Regional regulation of palatal growth and patterning along the anterior–posterior axis in mice
Authors: Hilliard Sylvia A. , Yu Ling , Gu Shuping , Zhang Zunyi , Chen Yi Ping
Published: September 2010

Cleft palate is a congenital disorder arising from a failure in the multistep process of palate development. In its mildest form the cleft affects only the posterior soft palate. In more severe cases the cleft includes the soft (posterior) and hard (anterior) palate. In mice a number of genes show differential expression along the anterior–posterior axis of the palate. Mesenchymal heterogeneity is established early, as evident from Bmp4‐mediated induction ofMsx1and cell proliferation exclusively in the anterior and Fgf8‐specific induction ofPax9in the posterior palate alone. In addition, the anterior palatal epithelium has the unique ability to induceShox2expression in the anterior mesenchymein vivoand the posterior mesenchymein vitro. Therefore, the induction and competence potentials of the epithelium and mesenchyme in the anterior are clearly distinct from those in the posterior. Defective growth in the anterior palate ofMsx1−/–andFgf10−/–mice leads to a complete cleft palate and supports the anterior‐to‐posterior direction of palatal closure. By contrast, theShox2−/–mice exhibit incomplete clefts in the anterior presumptive hard palate with an intact posterior palate. This phenotype cannot be explained by the prevailing model of palatal closure. The ability of the posterior palate to fuse independent of the anterior palate inShox2−/–mice underscores the intrinsic differences along the anterior–posterior axis of the palate. We must hitherto consider the heterogeneity of gene expression and function in the palate to understand better the aetiology and pathogenesis of non‐syndromic cleft palate and the mechanics of normal palatogenesis.
Evolution of cranial development and the role of neural crest: insights from amphibians
Authors: Hanken James , Gross Joshua B.
Published: September 2010

Contemporary studies of vertebrate cranial development document the essential role played by the embryonic neural crest as both a source of adult tissues and a locus of cranial form and patterning. Yet corresponding and basic features of cranial evolution, such as the extent of conservation vs. variation among species in the contribution of the neural crest to specific structures, remain to be adequately resolved. Investigation of these features requires comparable data from species that are both phylogenetically appropriate and taxonomically diverse. One key group are amphibians, which are uniquely able to inform our understanding of the ancestral patterns of ontogeny in fishes and tetrapods as well as the evolution of presumably derived patterns reported for amniotes. Recent data support the hypothesis that a prominent contribution of the neural crest to cranial skeletal and muscular connective tissues is a fundamental property that evolved early in vertebrate history and is retained in living forms. The contribution of the neural crest to skull bones appears to be more evolutionarily labile than that of cartilages, although significance of the limited comparative data is difficult to establish at present. Results underline the importance of accurate and reliable homology assessments for evaluating the contrasting patterns of derivation reported for the three principal tetrapod models: mouse, chicken and frog.
Developmental studies of the lamprey and hierarchical evolutionary steps towards the acquisition of the jaw
Authors: Kuratani Shigeru
Published: September 2010

The evolution of animal morphology can be understood as a series of changes in developmental programs. Among vertebrates, some developmental stages are conserved across species, representing particular developmental constraints. One of the most conserved stages is the vertebrate pharyngula, in which similar embryonic morphology is observed and the Hox code is clearly expressed. The oral developmental program also appears to be constrained to some extent, as both its morphology and the the Hox‐code‐default state of the oropharyngeal region are well conserved between the lamprey and gnathostome embryos. These features do not by themselves explain the evolution of jaws, but should be regarded as a prerequisite for evolutionary diversification of the mandibular arch. By comparing the pharyngula morphology of the lamprey and gnathostomes, it has become clear that the oral pattern is not entirely identical; in particular, the positional differentiation of the rostral ectomesenchyme is shifted between these animals. Therefore, the jaw seems to have arisen as an evolutionary novelty by overriding ancestral constraints, a process in which morphological homologies are partially lost. This change involves the heterotopic shift of tissue interaction, which appears to have been preceded by the transition from monorhiny to diplorhiny, as well as separation of the hypophysis. When gene expression patterns are compared between the lamprey and gnathostomes, cell‐autonomously functioning genes tend to be associated with identical cell types or equivalent anatomical domains, whereas growth‐factor‐encoding genes have changed their expression domains during evolution. Thus, the heterotopic evolution may be based on changes in the regulation of signalling‐molecule‐encoding genes.
Patterning the neural crest derivatives during development of the vertebrate head: insights from avian studies
Authors: Creuzet Sophie , Couly Gérard , Le Douarin Nicole M.
Published: September 2010

Studies carried out in the avian embryo and based on the construction of quail–chick chimeras have shown that most of the skull and all the facial and visceral skeleton are derived from the cephalic neural crest (NC). Contribution of the mesoderm is limited to its occipital and (partly) to its otic domains. NC cells (NCCs) participating in membrane bones and cartilages of the vertebrate head arise from the diencephalon (posterior half only), the mesencephalon and the rhombencephalon. They can be divided into an anterior domain (extending down to r2 included) in which genes of the Hox clusters are not expressed (Hox‐negative skeletogenic NC) and a posterior domain including r4 to r8 in which Hox genes of the four first paraloguous groups are expressed. The NCCs that form the facial skeleton belong exclusively to the anterior Hox‐negative domain and develop from the first branchial arch (BA1). This rostral domain of the crest is designated as FSNC for facial skeletogenic neural crest. Rhombomere 3 (r3) participates modestly to both BA1 and BA2. Forced expression of Hox genes (Hoxa2, Hoxa3 and Hoxb4) in the neural fold of the anterior domain inhibits facial skeleton development. Similarly, surgical excision of these anterior Hox‐negative NCCs results in the absence of facial skeleton, showing that Hox‐positive NCCs cannot replace the Hox‐negative domain for facial skeletogenesis. We also show that excision of the FSNC results in dramatic down‐regulation of Fgf8 expression in the head, namely in ventral forebrain and in BA1 ectoderm. We have further demonstrated that exogenous FGF8 applied to the presumptive BA1 territory at the 5–6‐somite stage (5–6ss) restores to a large extent facial skeleton development. The source of the cells responsible for this regeneration was shown to be r3, which is at the limit between the Hox‐positive and Hox‐negative domain. NCCs that respond to FGF8 by survival and proliferation are in turn necessary for the expression/maintenance of Fgf8 expression in the ectoderm. These results strongly support the emerging picture according to which the processes underlying morphogenesis of the craniofacial skeleton are regulated by epithelial–mesenchymal bidirectional crosstalk.
Barx1 and evolutionary changes in feeding
Authors: Miletich Isabelle , Buchner Georg , Sharpe Paul T.
Published: September 2010

During mouse embryonic development, the Barx1 homeobox gene is expressed in the mesenchymal cells of molar teeth and stomach. During early stages of molar development, Barx1 has an instructive role, directing the as yet undetermined ectomesenchymal cells in the proximal region of the jaws to follow a multicuspid tooth developmental pathway. We review here recent results showing an absence of stomach tissue in Barx1 mutant mice. The data strongly suggest that in the presumptive stomach mesenchyme Barx1 acts to attenuate Wnt signalling allowing digestive tract endoderm to differentiate into a highly specialized stomach epithelium. In the light of these new data, we discuss the possibility that evolutionary changes in the Barx1 gene could have simultaneously altered the dentition and the digestive system, therefore positioning Barx1 as a key gene in the evolution of mammals.
Reassessing theDlxcode: the genetic regulation of branchial arch skeletal pattern and development
Authors: Depew Michael J. , Simpson Carol A. , Morasso Maria , Rubenstein John L. R.
Published: September 2010

The branchial arches are meristic vertebrate structures, being metameric both between each other within the rostrocaudal series along the ventrocephalic surface of the embryonic head and within each individual arch: thus, just as each branchial arch must acquire a unique identity along the rostrocaudal axis, each structure within the proximodistal axis of an arch must also acquire a unique identity. It is believed that regional specification of metameric structures is controlled by the nested expression of related genes resulting in a regional code, a principal that is though to be demonstrated by the regulation of rostrocaudal axis development in animals exerted by the nestedHOM‐C/Hoxhomeobox genes. The nested expression pattern of theDlxgenes within the murine branchial arch ectomesenchyme has more recently led to the proposal of aDlxcode for the regional specification along the proximodistal axis of the branchial arches (i.e. it establishes intra‐arch identity). This review re‐examines this hypothesis, and presents new work on an allelic series ofDlxloss‐of‐function mouse mutants that includes various combinations ofDlx1,Dlx2,Dlx3,Dlx5andDlx6. Although we confirm fundamental aspects of the hypothesis, we further report a number of novel findings. First, contrary to initial reports,Dlx1,Dlx2andDlx1/2heterozygotes exhibit alterations of branchial arch structures andDlx2–/–andDlx1/2–/–mutants have slight alterations of structures derived from the distal portions of their branchial arches. Second, we present evidence for a role for murineDlx3in the development of the branchial arches. Third, analysis of compoundDlxmutants reveals four grades of mandibular arch transformations and that the genetic interactions ofcisfirst‐order (e.g.Dlx5andDlx6),transsecond‐order (e.g.Dlx5andDlx2) andtransthird‐order paralogues (e.g.Dlx5andDlx1) result in significant and distinct morphological differences in mandibular arch development. We conclude by integrating functions of theDlxgenes within the context of a hypothesized general mechanism for the establishment of pattern and polarity in the first branchial arch of gnathostomes that includes regionally secreted growth factors such asFgf8andBmpand other transcription factors such asMsx1, and is consistent both with the structure of the conserved gnathostome jaw bauplan and the elaboration of this bauplan to meet organismal end‐point designs.
Changes in the oviducal epithelium during the estrous cycle in the marsupial Monodelphis domestica
Authors: Kress Annetrudi , Morson Gianni
Published: September 2010

The Monodelphis oviduct can be divided into four anatomical segments: preampulla (comprising fimbriae and infundibulum), ampulla, isthmus with crypts and uterotubal junction. Ovaries are enclosed in a periovarial sac, the bursa, and in some specimens tubules of an epoophoron could be identified. In both structures non‐ciliated cells develop small translucent vesicles, which accumulate in the cell apices and presumably produce fluid as often seen in the bursa and in the tubules of the epooophoron. These vesicles do not stain with Alcian blue or PAS. The same applies also to the non‐ciliated cells of the fimbriae. The oviducal epithelium of ampulla and the surface epithelium of the isthmus consisting of ciliated and non‐ciliated, secretory cells undergo considerable changes during the estrous cycle. Proestrus shows low numbers of ciliated cells, some are in the process of neo‐ciliogenesis, non‐ciliated cells carry solitary cilia and few remnant secretory granules from the previous cycle may be found. At estrus the amount of ciliated cells in ampulla and isthmus has increased, most non‐cililated cells lost the solitary cilia, developed longer microvilli and formed numerous secretory granules in their cell apices. At postestrus secretory products, often surrounded by membranes, are extruded into the oviducal lumen and contribute towards egg coat formation. First signs of deciliation processes are apparent. Solitary cilia reappear.

At metestrus only few secretory cells are left with some secretory material. The lumen is often filled with shed cilia and cell apices. Proliferation of basal bodies within non‐secretory cells indicate the formation of new ciliated cells.

The non‐ciliated epithelial cells of the isthmic crypts form no secretory granules but accumulate a great number of translucent vesicles, which in contrast to the secretory granules do not stain with Alcian blue or PAS.
The functional development of Leydig cells in a marsupial
Authors: Butler Christopher M. , Shaw Geoff , Clark Joan , Renfree Marilyn B.
Published: September 2010

Leydig cells are the major source of androgen in the male mammal. We describe here for the first time the development of the Leydig cell in a macropodid marsupial, the tammar wallaby, Macropus eugenii. Leydig cells are first recognized morphologically 2 days after birth with the appearance of lipid droplets in the cytoplasm of certain interstitial cells. Lipid content closely matches the steroid content of the developing testis and marks the maturation of the steroid synthesis pathway in the tammar testis. Morphologically mature Leydig cells, marked by distinct mitochondria with tubular cristae and an extensive anastomosing network of smooth endoplasmic reticulum, are developed by day 10 after birth – the time of peak testosterone content in perinatal tammar testes. The volume percentage of each cell type in the testis does not change over time so the growth of each cellular component keeps pace with growth of the whole testis. There was no morphological or quantitative evidence of a change from one population of Leydig cells to another in the tammar testis as has been reported in several other species including the rat, mouse and human. Maturation of the testis is also marked by the development of tight junctions between the cell membranes of adjacent Sertoli cells. These appear around day 30 after birth and coincide with the onset of mitotic arrest in male germ cells. Overall, the development of the Leydig cell in the tammar wallaby follows a similar pattern to that seen in other mammals, although the start of Leydig cell differentiation is, like many other organ systems in marsupials, post natal, not fetal and there appears to be only a single population of Leydig cells.
The coronary arteries of the C57BL/6 mouse strains: implications for comparison with mutant models
Authors: Fernández B. , Durán A. C. , Fernández M. C. , Fernández‐Gallego T. , Icardo J. M. , Sans‐Coma V.
Published: September 2010

There are few detailed descriptions of the coronary arterial patterns in the mouse. Some recent reports on coronary anomalies in mutant mouse models have uncovered the importance of several genes (i.e. iv and connexin43) in coronary morphogenesis. These mutations spontaneously appeared (iv) or were generated (connexin43) in a C57BL/6 background, which is widely used for the development of mutant mice. We have studied the origin and course of the main coronary arteries of two C57BL/6 mouse strains. Unusual anatomical coronary arterial patterns were found, including: solitary ostium in aorta, accessory ostium, high take‐off, aortic intramural course, slit‐like ostium, sinus‐like ostium and origin of a septal artery from the left coronary artery. In humans, some of these conditions are clinically relevant. Most of these patterns, which differ from those observed in wild mice and Swiss albino mice, coincide with those previously found in iv/iv and connexin43 knockout mice. The results indicate that there is variability in the coronary arterial arrangement of the laboratory mouse. Care should be taken when analysing coronary phenotypes of mutant mouse models.