Primitive Region Research Articles

Spatiotemporal expression pattern of the zebrafish aquaporin 8 family during early developmental stages

Aquaporin 8 (Aqp8) is a transmembrane protein that is selectively permeated by water and some small solutes, and physiologically contributes to acid-base equilibrium in the gastrointestinal tract. Here, we described the characterization and spatiotemporal expression pattern of zebrafish aqp8 (zaqp8) gene family, including zaqp8a.1, zaqp8a.2, and zaqp8b, during the early developmental stages. The expression of zaqp8a.1 started first in the lateral plate mesoderm at the 12-somite stage (ss) and then expanded sequentially to the dorsal aorta, intersegmental blood vessels and then to the dorsal longitudinal anastomotic vessel at 24 h post fertilization (hpf). At 28 hpf, expression of zaqp8a.1 was also detected in the embryonic heart tube. Four days post fertilization (dpf), strong zaqp8a.1 expression was detected in the gastrointestinal tract and liver. By 72 hpf, the expression of zaqp8a.2 was first detected in the primitive gut region but not detected in the liver. The expression of zaqp8b was first detected in the intermediate mesoderm at 10 ss. From 24 hpf to 6 dpf, the proximal convoluted segment of the embryonic kidney was marked by zaqp8b expression Overall, these differential expression patterns of aqp8a.1, aqp8a.2, and aqp8b suggest that they possibly play distinct roles throughout the embryonic development by controlling or maintaining organ-specific cellular water homeostasis. Our study provides new evidence that organogenesis requires differential roles of Aqp8 proteins in zebrafish.

Evolution and function of the upper molar talon and its dietary implications in microbats.

The evolution of mammalian molars has been marked by transitions representing significant changes in shape and function. One such transition is the addition and elaboration of the talon, the distolingual region of the ancestral tribosphenic upper molar of therian mammals and some extinct relatives. This study uses suborder Microchiroptera as a case study to explore the adaptive implications of the expansion of the talon on the tribosphenic molar, specifically focusing on the talon's role in the compression and shear of food during breakdown. Three-dimensional computer renderings of casts of the upper left first molars were created for microbat species of a variety of dietary categories (frugivore, etc.) and physical properties of food (hard and soft). Relief Index (RFI) was measured to estimate the topography and function of the whole tooth and of the talon and trigon (the remaining primitive tribosphenic region) individually, in order to examine 1) how the shape of the whole tooth, trigon, and talon reflects the compromise between their crushing and shearing functions, 2) how whole tooth, trigon, and talon function differs according to diet, and 3) how the presence of the talon affects overall molar function. Results suggest that RFI of both the whole tooth and the trigon varies according to dietary groups, with frugivores having greater crushing function when compared with the other groups. The talon, however, consistently has low RFI (a flatter topography), and its presence lowers the RFI of the whole tooth across all dietary categories, suggesting that the talon is primarily functioning in crushing during food breakdown. The potential benefits of a crushing talon for microbats of various dietary groups are discussed.

Petrogenesis of primitive and evolved basalts in a cooling Moon: Experimental constraints from the youngest known lunar magmas

We have conducted high-temperature experiments over a range of pressures to constrain the petrogenesis of the youngest sampled lunar magmas, which have contrasting primitive and evolved compositions. Our results indicate that at ∼3 Ga, melting still occurred within the same mantle depth range that produced crystalline mare basalts for the previous ∼1 Ga, although our data cannot support or confirm that the shallowest extents of melting moved deeper into the mantle by ∼3 Ga, as is predicted by most thermal evolution models. Furthermore, melting still occurred in regions with low abundances of heat-producing elements. Basaltic lunar meteorite NEA 003A has some of the lowest abundances of incompatible trace elements among all mare basalts and no negative Eu anomaly. Our experiments show that NEA 003A is multiply saturated with olivine and low-Ca pyroxene on its liquidus at ∼1.1 GPa (∼215 km) and ∼1330 °C. If the primitive NEA 003A liquid composition is a minimally-modified melt, the relatively low Mg# of its source region (73–75), its lack of a Eu anomaly, and its chondritic initial Nd isotopic composition indicate its source region likely escaped mixing during mantle overturn with later-stage magma ocean cumulates that formed after plagioclase saturation. This condition would require the sources of the ultramafic glasses to have experienced cumulate mixing, or for assimilation of later-stage magma ocean cumulates by the ultramafic glass parental magmas before eruption in order to account for their higher Mg#'s and deeper negative Eu anomalies. Alternatively, NEA 003A may have undergone some fractional crystallization, in which case its more primitive source region would be deeper than 215 km and may approach the depth range of the ultramafic glass source regions. Iron- and incompatible trace element-rich basaltic lunar meteorites LAP 02205, NWA 032/479, and NWA 4734 have nearly identical bulk compositions and have a multiple saturation point on their high pressure liquidus at <0.6 GPa (<105 km) and 1150–1200 °C. The P–T conditions of this multiple saturation point are inconsistent with the expectation from thermal modeling of a thick, cold lunar elastic lithosphere at 3 Ga, and likely indicate these melts underwent fractional crystallization before eruption, thus increasing their abundances of incompatible trace elements. However, these LREE-enriched basalts possess a very deep negative Eu-anomaly but do not show other chemical fingerprints of KREEP, indicating that a component of Fe-rich, low-Ti late-stage magma ocean cumulates are required in their hybridized source region.

Rational Thought, Cognition and Knowledge

An exposition on how the brain works as theoretical application of the grand unified theory (GUT), this paper applies the new methodology of qualitative mathematics and modeling to trace the signals from the external world through the sense organs where they are encoded on brain waves and transmitted through the nerves to a primitive nodal region in the creative-integrative region (CIR) of the cortex. They form a tree of activated (vibrated) neural chains via resonance that triggers sensation and models a concept (cognition) there even after the signals from an event has stopped coming. The concept is defined by the vibration characteristics of the tree and its components. When thought leaves its focus on it, the tree reverts back to its normal vibration and transfers its components to their respective sensation regions for storage as memory in due course. Then the paper discusses recollection of concepts for use in thought and construction of knowledge and its application to wellness.

NI-58 * LOCATION OF GLIOBLASTOMA INTERSECTIING WHITE MATTER TRACTS PREDICT PATIENT PROGNOSIS AND RESPONSE TO BEVACIZUMAB PRIOR TO THERAPY

INTRODUCTION: Brain tumors are known to invade healthy brain along white matter tracts. We therefore hypothesized that specific white matter tracts would be associated with poorer prognosis based on their connection to primitive brain regions necessary for essential life functions. We also hypothesized that tumors in these regions treated with bevacizumab would alter patient survival. METHODS: 109 subjects with primary GBM tumors were retrospectively included in this study. Voxel-wise survival analyses were performed to test for spatial and treatment dependence of GBM survival prognosis. An intersection analysis was first performed between an enhancing tumor mask and template-space diffusion tensor imaging (DTI) derived tractography which highlighted voxels with tumor-intersecting white matter tracts. Maps of voxels with these tracts were made for each patient. A voxel-wise Kaplan-Meier test was performed comparing the survival times of patients with and without a tumor-intersecting white matter tract in that voxel. The same analysis was implemented to compare survival of participants with and without bevacizumab. This highlighted regions where survival was effected due to anti-VEGF treatment. A Monte Carlo simulation was performed to validate the observed survival differences induced by bevacizumab considering inconsistencies in treatment regimens seen in the patient population. RESULTS: Glioblastoma patients with tumors intersecting the right anterior thalamic radiation, right inferior fronto-occipital fasciculus, bilateral corticospinal tracts, and corpus callosum have decreased survival compared to those with tumors intersecting elsewhere. Patients treated with bevacizumab and who also had tumors intersecting the corpus callosum, corticospinal tract, or the thalamic radiations were found to be at a survival advantage when compared to those who did not receive bevacizumab. CONCLUSIONS: Patient prognosis is associated with the location of tumor intersecting WM tracts. A survival advantage was found in tumors intersecting specific WM tracts treated with bevacizumab.

Saliency Tree: A Novel Saliency Detection Framework

This paper proposes a novel saliency detection framework termed as saliency tree. For effective saliency measurement, the original image is first simplified using adaptive color quantization and region segmentation to partition the image into a set of primitive regions. Then, three measures, i.e., global contrast, spatial sparsity, and object prior are integrated with regional similarities to generate the initial regional saliency for each primitive region. Next, a saliency-directed region merging approach with dynamic scale control scheme is proposed to generate the saliency tree, in which each leaf node represents a primitive region and each non-leaf node represents a non-primitive region generated during the region merging process. Finally, by exploiting a regional center-surround scheme based node selection criterion, a systematic saliency tree analysis including salient node selection, regional saliency adjustment and selection is performed to obtain final regional saliency measures and to derive the high-quality pixel-wise saliency map. Extensive experimental results on five datasets with pixel-wise ground truths demonstrate that the proposed saliency tree model consistently outperforms the state-of-the-art saliency models.

Robert Southey's "Madoc" in America

The Madoc myth shows up in a range of late 18th century and early 19th century works on both sides of the Atlantic, from John Filson's Discovery, Settlement and Present State of Kentuckey (1784) in the United States to a 1791 series of essays in the British Gentleman's Magazine. Two of the best known British re-workings of myth were by the poet Edward Williams--known by his bardic name Iolo Morganwg--and by Robert Sou they. During the mid-1790s, both Sou they and Iolo made plans to emigrate to western Pennsylvania, then the gateway to the American West, in order to escape the stilling politics of counter-revolutionary Britain. Both were deterred by financial difficulties, and their poetic adaptations of the Madoc myth perhaps allowed them to indulge imaginatively in risk-free vicarious migration. However, their adaptations of the myth were also politically charged commentaries on Anglo-Welsh relations and on British ongoing colonial projects in North America. Both poets employed the Madoc myth to represent the western frontier as a place where the revolutionary ideals of liberty and equality might yet flourish. Yet their poems say more about the previous six centuries of English colonial government of than about the possibility of British settlement of the Ohio Valley. In his Address to the Inhabitants of Wales Iolo used the Madoc myth to imagine for the an American homeland that would free them from the economic and political discontents they experienced under British rule. Southey, as Caroline Franklin has shown, drew heavily on Iolo's knowledge of the myth for his epic poem Madoc (1795-1805). However, Madoc asserts the British right to the Ohio Valley by first affirming the justice of British colonial government of Wales. In employing the myth to claim the British continuing stake in the settlement of the Ohio Valley, Southey establishes a geographic and ideological equivalence between and the western frontier as primitive regions offering an escape from political oppression, but, somewhat paradoxically, only if they could first he brought under civilized colonial rule. In comparison to Ireland, Scotland, and England, contributed relatively few people and resources to the settlement of British North America. Some historians have questioned the existence of a distinctive diaspora, arguing that for intents and purposes 18th and early 19th century Welsh migration can be accounted part of the broader English movement (Horn 38). (1) Yet, the contribution to the Romantic-era lore of migration and settlement was disproportionately large. offered British migrants the legend of Prince Madoc, who, in the 12th century, left his home in war-torn and sailed to the Gulf of Mexico, where his people subdued, and in some tellings, mixed with, native tribes. The figure of Madoc has been traced to medieval poetry and he also shows up in late 16th century works describing Elizabethan explorations of the New World like Richard Hakluyt's Principall Navigations (1589). (2) The resurgence of the Madoc myth during the 1790s coincided with the increased emigration of artisans and farmers from into upstate New York, Pennsylvania, and the Ohio Valley, as the export of copper, brass, tinplate, and iron to British colonies disrupted traditional agricultural communities. The resurgence of the Madoc myth also coincided with the first major wave of westward migration from the eastern seaboard of the United States into the Ohio Valley. Accordingly, late 18th century versions of the myth located Madoc's descendants in what came to be called the mid-west, between the Mississippi and the Missouri rivers, where all the rival imperialisms of the continent--American, British, Spanish, and the ghost of the French--were inexorably coming to a focus (Williams, 67). Frontiersmen claimed to have seen Madoc's descendants, often referred to as Indians because of their supposed mixture with native American tribes, in the regions that would become Kentucky, Tennessee, and Ohio. …

Image Segmentation with Texture Gradient and Spectral Clustering

For some applications the whole image cannot be processed directly because it is inefficient and impractical. Segmentation results in a set of images that cover the entire image. This work proposes a two stage segmentation method, which effectively process both the textured and non-textured regions. Dual Tree Complex Wavelet Transform, an extension of discrete wavelet transform, extracts texture feature from the image and orientation median filtering reduces the double edge effect at the texture edges. Watershed transform of Gaussian gradient of combined texture and non-texture feature give the first stage segmentation. The initial segmentation into super-pixels reduces computational burden and the second stage uses spectral clustering technique to cluster these primitive regions. General Terms Feature, segmentation, interpolation, clustering, algorithm.

Evaluating SAR Sea Ice Image Segmentation Using Edge-Preserving Region-Based MRFs

This paper presents a new approach to sea ice segmentation in synthetic aperture radar (SAR) intensity images by combining an edge-preserving region (EPR)-based representation with region-level MRF models. To construct the EPR-based representation of a SAR image, edge strength is measured using instantaneous coefficient of variation (ICOV) upon which the watershed algorithm is applied to partition the image into primitive regions. In addition, two new metrics for quantitative assessment of region characteristics (region accuracy and region redundancy) are defined and used for parameter estimation in the ICOV extraction process towards desired region characteristics. In combination with a region-level MRF, the EPR-based representation facilitates the segmentation process by largely reducing the search space of optimization process and improving parameter estimation of feature model, leading to considerable computational savings and less probability of false segmentation. The proposed segmentation method has been evaluated using a synthetic sea ice image corrupted with varying levels of speckle noise as well as real SAR sea ice images. Relative to the existing region-level MRF-based methods, testing results have demonstrated that our proposed method substantially improves the segmentation accuracy at high speckle noise and achieves on average 29% reduction of computational time.

Fibroblast growth factor (FGF) signaling during gastrulation negatively modulates the abundance of microRNAs that regulate proteins required for cell migration and embryo patterning.

FGF signaling plays a pivotal role in regulating cell movements and lineage induction during gastrulation. Here we identify 44 microRNAs that are expressed in the primitive streak region of gastrula stage chicken embryos. We show that the primary effect of FGF signaling on microRNA abundance is to negatively regulate the levels of miR-let-7b, -9, -19b, -107, -130b, and -218. LIN28B inhibits microRNA processing and is positively regulated by FGF signaling. Gain- and loss-of-function experiments show that LIN28B negatively regulates the expression of miR-19b, -130b, and let-7b, whereas negative modulation of miR-9, -107, and -218 appears to be independent of LIN28B function. Predicted mRNA targets of the FGF-regulated microRNAs are over-represented in serine/threonine and tyrosine kinase receptors, including ACVR1, ACVR2B, PDGFRA, TGFBR1, and TGFBR3. Luciferase assays show that these and other candidates are targeted by FGF-regulated microRNAs. PDGFRA, a receptor whose activity is required for cell migration through the primitive streak, is a target of miR-130b and -218 in vivo. These results identify a novel mechanism by which FGF signaling regulates gene expression by negatively modulating microRNA abundance through both LIN28B-dependent and LIN28B-independent pathways.

Increased Anterior Cingulate Regional Homogeneity After Duloxetine Therapy in First-Episode, Drug-Naïve, Major Depressive Disorder With Panic Disorder Patients: A Case Series

Increased Anterior Cingulate Regional Homogeneity After Duloxetine Therapy in First-Episode, Drug-Naïve, Major Depressive Disorder With Panic Disorder Patients: A Case Series

Improved Fuzzy C-Means Clustering Algorithm Using Watershed Transform on Level Set Method for Image Segmentation

An innovative novel method for image segmentation is proposed in this paper, which combines the watershed transform, Improved FCM and level set method. The watershed transform is original used to pre-segment the image so as to get the initial partition of it. Some useful information of the primitive regions and boundaries can be obtained. The Improved fuzzy c-means (IFCM) was used to generate an initial contour curve which overcomes leaking at the boundary during the curve propagation. IFCM algorithm computes the fuzzy membership values for each pixel. On the source of IFCM the edge indicator function was redefined. Using the edge indicator function of an image was performed to extract the boundaries of objects on the origin of the pre-segmentation. Therefore, the proposed method is computationally efficient. The efficiency and accuracy of the algorithm is demonstrated. The above process of segmentation showed a considerable improvement in the evolution of the level set function.

Identification of differentially expressed genes in the heart precursor cells of the chick embryo

Genetic evidence has implicated several genes as being critical for heart development. However, the inducers of these genes as well as their targets and pathways they are involved with, remain largely unknown. Previous studies in the avian embryo showed that at HH4 Cerberus ( cCer) transcripts are detected in the anterior endomesoderm including the heart precursor cells and later in the left lateral plate mesoderm. We have identified a promoter element of chick cCer able to drive EGFP expression in a population of cells that consistently exit from the anterior primitive streak region, from as early as stage HH3+, and that later will populate the heart. Using this promoter element as a tool allowed us to identify novel genes previously not known to potentially play a role in heart development. In order to identify and study genes expressed and involved in the correct development and differentiation of the vertebrate heart precursor cell (HPC) lineages, a differential screening using Affymetrix GeneChip system technologies was performed. Remarkably, this screening led to the identification of more than 700 transcripts differentially expressed in the heart forming regions (HFR). Bioinformatic tools allowed us to filter the large amount of data generated from this approach and to select a few transcripts for in vivo validation. Whole-mount in situ hybridization and sectioning of selected genes showed heart and vascular expression patterns for these transcripts during early chick development. We have developed an effective strategy to specifically identify genes that are differentially expressed in the HPC lineages. Within this set we have identified several genes that are expressed in the heart, blood and vascular lineages, which are likely to play a role in their development. These genes are potential candidates for future functional studies on early embryonic patterning.

Correlating cell behavior with tissue topology in embryonic epithelia.

Measurements on embryonic epithelial tissues in a diverse range of organisms have shown that the statistics of cell neighbor numbers are universal in tissues where cell proliferation is the primary cell activity. Highly simplified non-spatial models of proliferation are claimed to accurately reproduce these statistics. Using a systematic critical analysis, we show that non-spatial models are not capable of robustly describing the universal statistics observed in proliferating epithelia, indicating strong spatial correlations between cells. Furthermore we show that spatial simulations using the Subcellular Element Model are able to robustly reproduce the universal histogram. In addition these simulations are able to unify ostensibly divergent experimental data in the literature. We also analyze cell neighbor statistics in early stages of chick embryo development in which cell behaviors other than proliferation are important. We find from experimental observation that cell neighbor statistics in the primitive streak region, where cell motility and ingression are also important, show a much broader distribution. A non-spatial Markov process model provides excellent agreement with this broader histogram indicating that cells in the primitive streak may have significantly weaker spatial correlations. These findings show that cell neighbor statistics provide a potentially useful signature of collective cell behavior.

New mixosaurid ichthyosaur specimen from the Middle Triassic of SW China: further evidence for the diapsid origin of ichthyosaurs

Recent cladistic analyses have all suggested a diapsid origin of ichthyosaurs. However, an intermediate evolutionary stage of the lower temporal region of ichthyosaurian skull between basal diapsids and derived ichthyosaurs has been absent from the fossil record. Here we describe the cranial skeleton of a new mixosaurid ichthyosaur specimen with a well-preserved lower temporal region from the Anisian Guanling Formation of eastern Yunnan. It is characterized by the most primitive lower temporal region within known ichthyosaurs. The primitive characters of the lower temporal region include both external and internal separation between the jugal and the quadratojugal, an anterior process of the quadratojugal, an apparent posteroventral process of the jugal, and a large lower temporal opening surrounded by the jugal, the postorbital, the squamosal, and the quadratojugal. The lower temporal region of this specimen provides the most direct evidence to the diapsid origin of ichthyosaurs. It also suggests that the disappearance of the lower temporal fenestra is caused initially by the reduction of the lower temporal arcade rather than the enlargement of the surrounding bones.

Affective neuroscience of the emotional BrainMind: evolutionary perspectives and implications for understanding depression

Cross-species affective neuroscience studies confirm that primary-process emotional feelings are organized within primitive subcortical regions of the brain that are anatomically, neurochemically, and functionally homologous in all mammals that have been studied. Emotional feelings (affects) are intrinsic values that inform animals how they are faring in the quest to survive. The various positive affects indicate that animals are returning to "comfort zones" that support survival, and negative affects reflect "discomfort zones" that indicate that animals are in situations that may impair survival. They are ancestral tools for living--evolutionary memories of such importance that they were coded into the genome in rough form (as primary brain processes), which are refined by basic learning mechanisms (secondary processes) as well as by higher-order cognitions/thoughts (tertiary processes). To understand why depression feels horrible, we must fathom the affective infrastructure of the mammalian brain. Advances in our understanding of the nature of primary-process emotional affects can promote the development of better preclinical models of psychiatric disorders and thereby also allow clinicians new and useful ways to understand the foundational aspects of their clients' problems. These networks are of clear importance for understanding psychiatric disorders and advancing psychiatric practice.

Hierarchical Partition of Unity Field Compositions (HPFC) for Optimal Design in the Presence of Cracks

In this paper, the theory of Hierarchical Partition of Unity Field Compositions (HPFC) is applied for the analysis of cracks and for the optimal design in the presence of cracks. In the HPFC procedure, the geometrical, material and behavioral fields defined over primitive domains are composed through Boolean operations similar to the Constructive Solid Geometry Procedure of CAD. Here, cracks are modeled as compositions of a continuous field with a discontinuous enrichment field. Convergence of the composed fields is ensured by developing constructions that obey the partition of unity property. Non-Uniform Rational B-Splines (NURBS) which are a common choice for modeling curves and surfaces in CAD systems are used to discretize the geometry, material, and behavioral felds (local approximations) over the primitive regions and to describe crack shapes as well as the discontinuous behavioral feld corresponding to the crack. Following several validation examples, crack propagation simulations without remeshing, and example problems aimed at determining the optimal location and shape of defense holes in the presence of fracture constraints are demonstrated.

English

Image segmentation, the division of a multi-dimensional image into groups of associated pixels, is an essential step for many advanced imaging applications. Image segmentation can be performed by recursively splitting the whole image or by merging together a large number of minute regions until a specified condition is satisfied. The split-and-merge procedure of image segmentation takes an intermediate level in an image description as the starting cutest, and thereby achieves a compromise between merging small primitive regions and recursively splitting the whole images to reach the desired final cutest. The proposed segmentation approach is a split-andmerge technique. The conventional split-and-merge algorithm is lacking in adaptability to the image semantics because of its stiff quadtree-based structure. In this paper, an automatic thresholding technique based on bimodality detection approach with non-homogeneity criterion is employed in the splitting phase of the split-and-merge segmentation scheme to directly reflect the image semantics to the image segmentation results. Since the proposed splitting technique depends upon homogeneity factor, some of the split regions may or may not split properly. There should be rechecking through merging technique between the two adjacent regions to overcome the drawback of the splitting technique. A sequential-arrange-based or a minimal spanning-tree based approach, that depends on data dimensionality of the weighted centroids of all split regions for finding the pair wise adjacent regions, is introduced. Finally, to overcome the problems caused by the splitting technique, a novel merging technique based on the density ratio of the adjacent pair regions is proposed. The algorithm has been tested on several synthetic as well as real life data and the results show the efficiency of the segmentation technique. Defence Science Journal, 2010, 60(3), pp.290-301 , DOI:http://dx.doi.org/10.14429/dsj.60.356

Masticatory Loading, Function, and Plasticity: A Microanatomical Analysis of Mammalian Circumorbital Soft‐Tissue Structures

In contrast to experimental evidence regarding the postorbital bar, postorbital septum, and browridge, there is exceedingly little evidence regarding the load-bearing nature of soft-tissue structures of the mammalian circumorbital region. This hinders our understanding of pronounced transformations during primate origins, in which euprimates evolved a postorbital bar from an ancestor with the primitive mammalian condition where only soft tissues spanned the lateral orbital margin between frontal bone and zygomatic arch. To address this significant gap, we investigated the postorbital microanatomy of rabbits subjected to long-term variation in diet-induced masticatory stresses. Rabbits exhibit a masticatory complex and feeding behaviors similar to primates, yet retain a more primitive mammalian circumorbital region. Three cohorts were obtained as weanlings and raised on different diets until adult. Following euthanasia, postorbital soft tissues were dissected away, fixed, and decalcified. These soft tissues were divided into inferior, intermediate, and superior units and then dehydrated, embedded, and sectioned. H&E staining was used to characterize overall architecture. Collagen orientation and complexity were evaluated via picrosirius-red staining. Safranin-O identified proteoglycan content with additional immunostaining performed to assess Type-II collagen expression. Surprisingly, the ligament along the lateral orbital wall was composed of elastic fibrocartilage. A more degraded organization of collagen fibers in this postorbital fibrocartilage is correlated with increased masticatory forces due to a more fracture-resistant diet. Furthermore, the lack of marked changes in the extracellular composition of the lateral orbital wall related to tissue viscoelasticity suggests it is unlikely that long-term exposure to elevated masticatory stresses underlies the development of a bony postorbital bar.

Nasal Dermoid Cyst and Nasal Glioma with Intracranial Extension

These congenital midline nasal masses are the result of a failure of normal neural crest cell embryology. The ectodermal anterior neuropore (primitive frontonasal region) forms medial to the optic recess of the sphenoid sinus in the third week of gestation, and the frontal, nasal, and ethmoid structures form in the area immediately proximal to the anterior neuropore.3 Through the eighth week of gestation, the following occur. The fonticulus frontalis (gap between frontal and nasal bones) fuses with the foramen cecum (region between ethmoid and frontal bones connecting with the prenasal space) in the area of the future cribriform plate, separating intracranial contents from the nose and extracranial structures. Failure of closure here can lead to encephaloceles. Gliomas can form when faulty closure of the anterior neuropore leads to the development of rests of CNS tissue extracranially. Dermoids may develop after faulty closure of the fonticulus frontalis, which allows dermal elements to invaginate between the nasal bones and cartilage. Intracranial connections can be seen with all of these. None should be biopsied until radiographic imaging is obtained to determine intracranial extension, as this could be associated with CSF leak. Intracranial connection is also associated with an increased risk of meningitis.3