Another look at an old face: biomechanics of the neandertal facial skeleton reconsidered

Some of the characteristic features of the neandertal face can be explained as adaptations to resist stresses generated by high occlusal loads on the anterior teeth combined with long lever arms of external forces. This interpretation agrees with that offered by Yoel Rak (J. hum. Evol. 15, 151–164, 1986). However, the nature of the stresses and the mechanical adaptations to counter them are estimated differently. The peripheral position of the walls of the maxillary sinuses imparts torsional resistance in all directions to the projecting part of the face. The inflated maxilla and convex midfacial profile reduce bending in the sagittal plane, as does the straight infrazygomatic contour in the frontal plane. The elimination of angles between the infraorbital plate, the maxillary side walls and the zygomatic body reduces local stress concentrations.     

Shape and volume of craniofacial cavities in intentional skull deformations

Intentional cranial deformations (ICD) have been observed worldwide but are especially prevalent in preColombian cultures. The purpose of this study was to assess the consequences of ICD on three cranial cavities (intracranial cavity, orbits, and maxillary sinuses) and on cranial vault thickness, in order to screen for morphological changes due to the external constraints exerted by the deformation device. We acquired CT‐scans for 39 deformed and 19 control skulls. We studied the thickness of the skull vault using qualitative and quantitative methods. We computed the volumes of the orbits, of the maxillary sinuses, and of the intracranial cavity using haptic‐aided semi‐automatic segmentation. We finally defined 3D distances and angles within orbits and maxillary sinuses based on 27 anatomical landmarks and measured these features on the 58 skulls. Our results show specific bone thickness patterns in some types of ICD, with localized thinning in regions subjected to increased pressure and thickening in other regions. Our findings confirm that volumes of the cranial cavities are not affected by ICDs but that the shapes of the orbits and of the maxillary sinuses are modified in circumferential deformations. We conclude that ICDs can modify the shape of the cranial cavities and the thickness of their walls but conserve their volumes. These results provide new insights into the morphological effects associated with ICDs and call for similar investigations in subjects with deformational plagiocephalies and craniosynostoses. Am J Phys Anthropol 151:110–119, 2013. © 2013 Wiley Periodicals, Inc.     

A longitudinal study of the growth pattern of the maxillary sinus in the pig-tailed macaque (Macaca nemestrina)

The ontogeny of sexual dimorphism in maxillary sinus size in a nonhuman primate was studied longitudinally for a period of 8 years in 25 female and 25 male Macaca nemestrina via lateral cephalograms. The maxillary sinus was traced and its area digitized. The growth of female maxillary sinuses was described with a Gompertz model; the best fit to the male data was obtained by the logistic model. Growth curves and confidence intervals revealed that the sinuses grew in a similar fashion for 3-4 years in both sexes. After this, female sinuses achieved a plateau in their development while male sinuses continued to grow. Confidence intervals suggested that size dimorphism appeared at the age of 6.3 years. Lowess regression indicated growth spurts in both sexes. Females experienced an earlier and smaller spurt than males. Sexual dimorphism in maxillary sinus size seems to represent a combination of differences in velocity and length of growth. This study indicates that growth of the maxillary sinus follows closely the growth in body size. Nevertheless, due to the variation in sinus size in Macaca, it is questionable if body size is the main determinant of maxillary sinus size. It is suggested that Macaca, with its wide geographic range and different environments, is an especially appropriate genus to use to test hypotheses about the evolution of skull pneumatization in primates.     

Electron Microscope Observations on the Effects of Polymixin B Sulfate on Cell Walls of Chlamydia psittaci

The effects of polymixin B sulfate on cell walls of mature elementary body (EB) and of immature developmental reticulate body (RB) of Chlamydia psittaci were investigated. When purified EB were treated with polymixin (10(4) units per ml or more) at 37 C for 60 min, about 70% of EB was found to be covered with a number of projections. Further incubation did not increase the percentage affected. The infectivity after treatment as assayed by the inclusion counting technique was reduced by 70% of the original titer. These results suggest that EB with the projections are no longer infective. The projections had obscure outlines and were 20 to 40 nm in diameter when seen in thin sections. In the negatively stained preparations, the projections were composed of aggregations of fine particles 4 to 5 nm in diameter. Treatment with sodium dodecyl sulfate at the same concentration used for cell wall isolation removed the projections completely, and the cell walls were converted to rather ragged forms apparently composed of outside and inside layers. When RB cell walls prepared from infected cells at 18 hr after infection were treated with polymixin at the same concentration, the projections having the same morphology with those seen on treated EB cell walls were observed only on the inside surface of cell wall.     

Automated classification of cells in electron microscopic images of lymphoreticular tissue.

In classifying cells in tissue sections, one must consider the fact that only random projections of cells and of subcellular structures are available in the two-dimensional image. Therefore, measurement values that solely reflect the size of such projections cannot be taken on their own as a basis for cell classification. More complex morphologic features such as shape, texture and distribution pattern of cells and their components should be analyzed. Using cell nuclei as an example, the relationship between such features and geometric measurement values is evaluated. It can be shown that a well balanced combination of geometric parameters provides a suitable basis for reproducing the visual preclassification of lymphocytes in tissue sections. Moreover, using a cluster algorithm, which allows different levels of similarity to be defined, a hierarchical sequence of subclusters turns out, indicating the heterogeneity of the visually determined cell classes. Whether or not these subclusters can be correlated to functionally defined subpopulations of lymphocytes remains a matter for further investigation.     

Distribution of type IV collagen, laminin, and fibronectin during maxillary process formation in the chick embryo

The presence and distribution of laminin, type IV collagen, and fibronectin were analyzed in the facial primordia and developing primary palates of chick embryos from stages of development corresponding to maxillary process formation and primary palate closure. Frozen sections through the maxillary process and roof of the stomodeum were prepared for indirect immunofluorescence employing a biotin-avidin system using monoclonal antibodies against laminin, type IV collagen, and fibronectin. Light microscopic examination of sections stained with antibodies against type IV collagen revealed a much stronger fluorescent signal in the roof of the stomodeum than in the maxillary process at all stages examined. Regional differences in signal intensity and staining patterns were noted within the maxillary process; for example, the lateral surface of the maxillary process displayed a much less intense signal at most stages examined than the inferior and medial surfaces. The signal from sections of the maxillary process stained with laminin was much stronger than the signal from the same tissues stained with collagen. Regional differences in signal intensity within the maxillary process were minimal in sections stained with antibodies to laminin, in contrast to the differences seen in sections stained with antibodies to type IV collagen. Differences in signal intensity between the maxillary process and the roof of the stomodeum with laminin were slight. Sections stained with antibody to fibronectin displayed intense staining throughout the mesenchyme in both the maxillary process and the roof of the stomodeum. From comparison of the data of type IV collagen and laminin, the following hypothesis is proposed. In structures which undergo rapid change in form, such as the facial primordia, collagen distribution and/or organization is altered to a much greater extent than laminin, which is more uniformly distributed and which may be required for structural support of other developmentally regulated macromolecules. Where tissue morphology must be maintained, such as the roof of the stomodeum, the concentration and organization of type IV collagen is maintained in a manner that confers stability to these regions.     

Microscopic structure of the mesenteric lymph nodes of monkeys]

The structure and cytoarchitectonics of mesenterial lymph nodes were studied in thin histological sections by different methods. Under study were 5 rhesus monkeys and 3 hamadryas baboons. The square surface of different structural elements of the nodes (the cortical and medullary substances, follicles, the connective tissue framework, sinuses) occupied by them in sections was calculated and the amount of cellular elements was determined (%). Comparison of the data obtained in rhesus monkeys and baboons speaks of certain species-specific features of the organs under study. The morphological picture of lymph node sections in baboons (as compared with rhesus monkeys) might suggest earlier ageing of nodes in baboons.     

Freeze-fracture investigation of the red pulp of human spleen

This study concerns the morphology of the human spleen in freeze-fracture replicas and compares this with the findings in ultrathin sections. The material investigated consisted of two spleens resected at gastrectomy and one resected because of splenomegaly in a case of hairy cell leukaemia. The current concepts concerning the ultrastructure of the spleen were generally confirmed with the freeze-fracture technique. The sinus walls were found, as expected, to consist of closely fitting endothelial cells, which were identifiable in freeze-fracture replicas by numerous caveolae of the cell membrane. Contrary to the opinion upheld in the literature, the sinus endothelial cells were occasionally found to be connected by desmosomes or maculae adhaerentes. Corresponding to the finding of desmosomes in ultrathin sections, focal collections of intramembranous particles were observed in freeze-fracture replicas and a positive immunohistochemical reaction for desmoplakin in the sinuses was found at the light microscopic level. The view generally held in the literature that sinus endothelial cells can exhibit tight junctions was not confirmed. However, such junctions were found between vascular endothelial cells. The ring fibres of the sinuses, which are closely connected to the sinus endothelial cells through contractile fibres, apparently have various functions. Firstly, they contribute towards maintaining mechanical stability. Secondly, they represent basement membranes through which exchange occurs between the sinus endothelial cells and their surroundings. This is indicated by the caveolae and vesicles that are often found here in large numbers and in focal collections. Hairy cells exhibit no features in freeze-fracture replicas to suggest a cytogenetic relationship to interdigitating reticulum cells.     

Prevalence and ultrastructure of three types of Sarcocystis in mule deer, Odocoileus hemionus (Rafinesque), in Montana

Infection with Sarcocystis (Protozoa: Sarcocystidae) was diagnosed in 130 of 153 (85%) samples of muscle from mule deer around Bozeman, Montana. Three structurally distinct mature and microscopic sarcocysts with characteristic cyst walls were found. Cyst walls of type I sarcocysts were about 2 microns thick and had characteristic inverted tee-shaped villar projections; these cysts were considered to be S. hemionilatrantis Hudkins and Kistner, 1976. Cyst walls in type II sarcocysts were thick-walled (about 7 microns) and their villar projections were 6.7 X 1.1 micron. The core of the villar projections consisted of granular material and some filamentous structures. Bradyzoites were 11.6 X 2.8 microns and were tightly packed in compartments. Cyst walls of type III sarcocysts were also thick-walled (about 9 microns) but the villar projections were 8.5 X 4.7 microns. Bradyzoites were 13 X 3.3 microns and were loosely arranged in compartments.     

An electron microscopic study of the location of teichoic acid and its contribution to staining reactions in walls of Streptococcus faecalis 8191.

The location of the glucosylated teichoic acid in whole cells and isolated walls of Streptococcus faecalis 8191 has been investigated using ruthenium red, gold-labelled concanavalin A and concanavalin A-peroxidase-diaminobenzidine. Dense laminae were revealed in sections of osmium-fixed walls stained with ruthenium red which corresponded to similar regions stained by uranyl and lead. Such regions were not seen after teichoic acid had been extracted, suggesting that the uptake of stain was by teichoic acid. However, these regions were not labelled on exposure to gold concanavalin A or concanavalin A-peroxidase-diaminobenzidine; these stains indicated that teichoic acid was situated between the dense laminae, although the distribution of stain could have been due to the inability of the concanavalin A stains to penetrate deeply. Chemical binding studies showed that the teichoic acid was the major uranyl binding component in isolated walls, from which it might be inferred that teichoic acid was located in the densely staining regions. However, since osmification significantly increased the binding of uranyl (and lead stains) to non-teichoic acid material, such an inference was not necessarily valid. It is concluded that the presence of teichoic acid can be demonstrated in certain regions of the wall by concanavalin A, but its presence in densely staining regions has not been established. These experiments therefore suggest that teichoic acid may not be intimately associated with the mechanisms that generate contrast patterns in stained sections of cell walls of Streptococcus faecalis.     

Nature of human spleen red pulp cells with special reference to sinus lining cells

Summary A histological and cytological as well as enzyme histo- and cytochemical analysis (alpha-naphthyl acetate esterases, naphthol AS acetate esterases, naphthol AS-D chloroacetate esterases, acid and alkaline phosphatases) of human spleen cells in sections and imprints was carried out with special reference to sinus lining cells. These cells show strong naphthol AS esterase activity and no or only little alpha-naphthyl acetate esterase and acid phosphatase activity. Thus they can be distinguished from reticular cells in pulp cords and from other macrophages in cords and sinuses. From the morphological and enzyme histochemical aspect it can be deduced that the sinus lining cells are a distinct cell type of the human spleen. The comparison of these enzyme cytochemical findings with the results of biochemical and electron microscopical investigations suggests that reticular cells of pulp cords and littoral cells of sinuses also have different functions: reticular cells seem to have a high phagocytotic activity while littoral cells seem to be only facultatively phagocytic.This work was supported by the Deutsche Forschungsgemeinschaft.     

Occurrence of a special type of "polypoid cushion" and valve-like formations in arteries]

Intraarterial structures, known as 'polypoid cushions' and 'valve-like' projections at arterial branching sites, were observed in serial sections of human cleft lip and nasal mucous membrane biopsies. A particular type of 'polypoid cushions', which additionally contains a small artery in its center, is distinguished. It is suggested that both the particular type of 'polypoid cushions' and these 'valve-like' projections originate from the invagination of the entire vessel wall at arterial branching sites according to the location of the dissection or damage. The differences between these 'valve-like' formations and genuine arterial valves are mentioned.     

The Open Microcirculation in Human Spleens: A Three-Dimensional Approach

It has long been debated whether the red pulp of human spleens harbors an open or a closed microcirculation or both. To solve this issue, the authors differentially stained the endothelium in red pulp arterial microvessels and in venous sinuses using brightfield and fluorescence immunohistology with reagents against CD34 and CD141. Three-dimensional models of red pulp arterial microvessels and sinuses were derived from serial double-stained paraffin sections with the help of license-free open-access software. In each model, arterial microvascular ends were traced and verified by reference to the original serial sections. In total, 142 ends were analyzed in the specimens of three individuals. None of these ends was connected to a sinus, suggesting that the human splenic red pulp harbors an entirely open circulatory system. Thus, the spleen is the only human organ where blood passes through spaces not lined by endothelia or other barrier-forming cells.     

Junctions between microtubule walls.

We have studied lateral associations of microtubule walls by electron microscopy and image analysis. In negative stain they are observed as composite sheets having two or more domains usually facing in opposite directions. Thin sections show a variety of complex tubular arrays including structures resembling flagellar doublets and centriolar triplets. It appears that protofilaments can combine in two distinct modes, one leading to microtubule walls, the other forming junctions between walls. Both kinds of bonds seem to be inherent properties of tubulin and not of microtubule-associated protein.     

Enigmatic Diversity of the Maxillary Sinus in Macaques and Its Possible Role as a Spatial Compromise in Craniofacial Modifications

Understanding the evolutionary significance of morphological diversity is a major goal of evolutionary biology. Paranasal sinuses, which are pneumatized hollow spaces in the face, have attracted attention from researchers as one of the most intriguing traits that show unexpected variations. Macaques are one genus of primates that have accomplished adaptive radiation and therefore present an excellent opportunity to investigate the phenotypic diversification process. Using the large data set of computed tomography images of macaques (172 specimens from 17 species), we applied geometric morphometrics and multivariate analyses to quantitatively evaluate the maxillary sinus (one of the largest paranasal sinuses), the outer craniofacial shape, and nasal cavity. We then applied phylogenetic comparative methods to test their morphological interactions, phylogenetic, and ecogeographical significances. The results showed that the relative maxillary sinus size was significantly associated with the relative nasal cavity size and with the zygomaxillary surface shape. The relative nasal cavity size had ecogeographical correlations and high phylogenetic signal, whereas the zygomaxillary surface shapes were ecogeographically and phylogenetically irrelevant. The significant interactions with multiple surrounding traits that have experienced different evolutionary processes probably enable the maxillary sinus to show enigmatic diversity, which is independent of phylogeny and ecology. The pliable nature of the maxillary sinus, which is positioned between the nasal airways and the outer face, may play a role as a spatial compromise in craniofacial modifications.     

Maxillary sinusitis in Medieval Chichester,England

Maxillary sinusitis is a common medical complaint, affecting more than 30 million people per year in the United States alone. Very little palaeopathological work on this disease has been carried out, probably because of the enclosed nature of the sinuses in intact skulls and the lack of a suitable method for examination. This study tested the hypothesis that maxillary sinusitis was more common in people with leprosy than in people without it in Medieval England. The prevalence of maxillary sinusitis by age and sex was recorded in 133 individuals, some diagnosed as being leprous, derived from a later Medieval (12th to 17th centuries AD) urban hospital population at Chichester, Sussex, England using both macroscopic and endoscopic methods of examination. Of the 133 individuals with one or both sinuses available for examination, 54.9% (73) had evidence of bone change within the sinuses. There was no difference in prevalence between those with leprosy and those without, although clinical studies suggest that over 50% of lepromatous leprous individuals may develop sinusitis. Comparison with another study on Medieval British sites with a 3.6% prevalence (3 of 83) indicates that the prevalence at Chichester is much greater. The problems with diagnosing sinusitis are addressed and reasons behind the high frequency in this study are discussed. Aetiological factors predisposing to maxillary sinusitis are considered with reference to possible environmental conditions prevailing in the later Medieval period in Britain. © 1995 Wiley-Liss, Inc.     

Nasal cavities and paranasal sinuses in newborns and children]

The paranasal or accessory nasal sinuses begin their development as evaginations of the mucosa during the 3rd and 4th fetal months, but undergo their major expansion after birth according to the development of the facial cranium and the teeth. While in the newborn the sphenoidal and frontal sinuses are still only predispositioned, the ethmoidal labyrinth and particularly the maxillary sinus are of appreciable size. In the 4-year-old the frontal and sphenoidal sinuses are already developed and in the 12-year-old the paranasal sinuses reach their final form and a size equivalent to the adult.     

Anatomy and ultrastructure of epidermal cells in the haustorium of a parasitic flowering plant,Cuscuta japonica, during attachment to the host

Changes of epidermal cells in the haustorium of the parasiticCuscuta japonica during its attachment to the host plantimpatiens balsamina were studied with light and electron microscopy. In the transverse sections of dodder stems not in contact with the host, epidermal cells had rounded outlines. However, when haustorial initials developed in the cortex of the parasite stem at the contact site, the epidermal cells had more dense cytoplasm and conspicuous nuclei than before, and their outline was flat in the longitudinal section. As meristem cells developed from those initials, the epidermal cells became more elongated. When the haustorium was fully matured, the apical tips of the elongated epidermal cells at the contact site branched like toes, producing numerous projections via cell wall invaginations. This event caused spaces to form between the projections; coincidently, the surface area of the apical ends of the epidermal cells increased. The dense cytoplasm at those projections contained prominent nuclei and abundant other organelles, suggesting a active metabolism. Osmiophilic particles, releasing into the cell walls from the cytoplasm, were though to be associated with the loosening and elongating of the epidermal cell walls. Dense and homogeneous materials were secreted within the spaces between the projections. These materials could play an important role in cementing the haustorium onto the surface of the host organ.     

Water-soluble contrast media with increased viscosity for the diagnosis of diseases of the paranasal sinuses, bronchi and esophagus]

Water-soluble contrast agents with one of the polymers, cellulose derivatives or polyvinyl alcohol, were used in contrast examinations of paranasal sinuses, bronchi, and esophagus. Experiments have demonstrated the advantages of contrast agents basing on polymers as against the traditional oil-containing agents. Method for double-contrast examination of maxillary and frontal sinuses has been developed. Lowered concentrations of water-soluble contrast agents (i. e. diluted with distilled water) are recommended to be used, this permitting to save the reagents. A table of recommended dilutions of contrast media is presented. A total of 245 patients were examined, making use of contrast media of high viscosity.     

A measure for the angle between projections based on the extent of correlation between corresponding central sections

A pre-condition for the ab initio assignment of Euler angles to a set of projections from an asymmetric object is that at least three of the available projections correspond to rotations about different axes. For symmetric objects this condition may be relaxed. There are some applications of single-particle electron microscopy, such as the reconstruction of filamentous macromolecular assemblies, where all available projections more-or-less correspond to rotations about a common rotation axis making it difficult to satisfy this condition. Here, a method has been developed to overcome this problem, based on the fact that the correlation between two central sections of the Fourier transform of a compact object will not be limited to an infinitesimal central line but will have a finite extent, which is related to the angle between the corresponding projections. Projections from model filaments, with different degrees of rotational symmetry about the long axis, have been used to test the methodology. The results show that angle determination is robust down to signal-to-noise ratios as low as 2 and that, in general, the error decreases as the degree of symmetry increases. The method has been used to assign angles to a set of negatively stained muscle thick filament projections to obtain an initial 3D reconstruction. The main features of the projections are seen to be faithfully reproduced in the reprojections from the reconstruction. A real-space adaptation of this method is also discussed.