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PubMed2005

Visualizing facial shape regression upon 2nd to 4th digit ratio and testosterone.

Sex steroids are supposed to moderate the differences between male and female facial characteristics. Studies on women's preferences for male faces reported increased preferences for facial architecture developed under the influence of testosterone as this may indicate masculinity, dominance and social status. Recent research demonstrates that facial sexual dimorphism does not only develop at puberty but may be organized much earlier in ontogeny. However, the actual cause and timing of variation in facial shape due to sex-steroids remains speculative. This study uses data from Neave and colleagues who measured digit ratio (2D:4D) as a proxy to prenatal testosterone and also salivary testosterone samples in order to study differential effects of androgens on perceived male facial shape. Male facial shape was regressed upon 2D:4D ratio and circulating levels of testosterone by means of geometric morphometric methods. We found some evidence for opposite effects of early androgen action (via 2D:4D ratio) on the upper and the lower face respectively (i.e. low 2D:4D ratio results in a relatively robust and prominent lower face), whereas circulating testosterone seems to cause a rather uniform elongation of the face. Local deformations primarily show pronounced and medially tailed eyebrows for the shapes associated with increasing salivary testosterone. These preliminary results suggest that prenatal and pubertal testosterone have differential effects on male facial shape that should be considered in future studies on women's preferences towards male facial appearance.

Adolescent↗
PubMedDate not supplied

[An analysis of form variability by the methods of "geometrical morphometry": the demonstration of its potentials exemplified by the gnathosoma of ticks (Acari: Ixodes) and by the molar of voles (Mammalia: Alticola)].

New applied computer programs GRF, TPSRW, TPSLINE realize an idea of geometrical morphometrics and make it possible to study shape variation. Some results of their application are considered. Gnathosoma shape transformations among age and sex phases in tick, Ixodes ricinus, and third upper molar shape transformations among subspecies of vole, Alticola argentatus, are study cases. In tick, gnathosoma shape changes most significantly in males than in females, and age variation in total has twice higher magnitude as compared with sex differences. In vole, the most variable part of the tooth is talon, in general its complexity increases from south to north of the species area. A possibility of "vector" representation of principally "scalar" individual variation of the tooth shape is shown.

Aging↗
PubMedDate not supplied

[The use of the methods of geometrical morphometry in the systematics of ixodid ticks (Ixodidae)].

It is shown that morphological characters, such as a form of gnathosoma, usually considered as qualitative one, may be properly analyzed on a quantitative basis by means of the geometrical morphometric methods. In particular, an extraction of relative warps (RW) from a shape variation using TPSRW computer program makes it possible to run standard statistical procedures over matrices of RW values. This approach is demonstrated by the analysis of gnathosoma shape differences in 4 Ixodes species and 3 Dermacentor species, with a discriminant analysis being employed as a statistical routine. It is shown that differences among I. persulcatus and I. ricinus are statistically significant (by F-criterium) in all ontogenetic phases, while in the case of I. laguri and I. redikorzevi this is true only for the larval phase. Magnitudes of the gnathosoma shape variation among species (by F criterium) are similar within both Ixodes (s, str.) and Serdjukovia subgenera. The differences among subgenera of the genus Dermacentor are more significant.

Animals↗
PubMed2006

The geometric configuration and morphometry of the rabbit oesophagus during luminal pressure loading.

The aim of the present study was to determine the geometric configuration and morphometric dimensions in the rabbit oesophagus during luminal pressure loading. The geometric configuration is of fundamental importance because it is related to stress and strain and determines the resistance to flow. The oesophagus was excised from rabbits, transferred to an organ bath and stretched to the in vivo length. Cannulas were inserted into both ends and each oesophagus was subjected to a luminal pressure up to 0, 1, 2, 5 and 10 cm H(2)O. After equilibrium was reached, the oesophagus was snap-frozen in liquid nitrogen. Sections were cut from five locations in the oesophagus and videotaped in the frozen state. Geometric and morphometric data including perimeter, circularities, area, thickness, buckles and strains in different layers were obtained from the video images. These variables did not show axial variation in the oesophagus. All variables changed as a function of the pressure. The whole wall thickness decreased as an inverse function of the pressure. The thickness decrease was mainly due to thinning of the submucosa and muscle. The number of buckles decreased from 4.05 +/- 0.34 at 0 cm H(2)O pressure to 0.07 +/- 0.07 at 10 cm H(2)O. Circumferential Green strain-pressure curves for the various layers all showed an exponential pattern. The curve obtained at the submucosa-muscle layer interface was located to the right of the other curves, indicating that the muscle layer was softest. The data obtained in this study will be useful for further modelling of the mechanics of the oesophagus.

Animals↗
PubMed1994

Morphometric analysis of exudative retinal arterial macroaneurysms: a geometrical approach to exudate curves.

We studied morphometrically the color transparencies and fluorescein angiograms of 5 patients with six exudative retinal arterial macroaneurysms. Our aim was to express the dependence of the exudate morphology upon the location of the macroaneurysm with an algebraic polynomial analysis. We derived the second-degree conical equations of the exudate curves and computed the location of their cardinal descriptive parameters. The relationship between the site of the macroaneurysms and the computed hypothetical parameters of their exudate curves revealed that the structural features of the exudates are dependent upon the distance of the macroaneurysm to the foveola, the gravitational force and the clearing capacity of the venous net. The point where the macroaneurysm develops approximately 3 mm from the center of the macula seems to be a 'crucial point'. Macroaneurysms located closer than this point may cause the exudates that occupy the fovea and create severe visual loss.

Aneurysm↗
PubMed2004

A quasi-static three-dimensional, mathematical, three-body segment model of the canine knee.

A mathematical, three-dimensional, anatomically accurate model of the canine knee was created to determine the forces in the knee ligaments and the knee joint reaction forces during the stance phase of a slow walk. This quasi-static model considered both the tibio-femoral and patello-femoral articulations. The geometric and morphometric data of the hind limb were obtained from cadaver data. Muscle forces acting on the femur and the hip joint reaction force were determined by numerical optimization. Ligaments were modeled as non-linear-springs. Ligament material properties were obtained from the literature pertaining to the human knee. The model consists of-28 non-linear algebraic equations describing equilibrium of the femur and the patella, and geometric constraints. This system of equations was solved by a non-linear least-squares method. Results are presented for a knee with an intact cranial cruciate ligament (CCL) and for a knee with a ruptured CCL. Forces predicted to occur in the CCL by analysis of the model were found to be very similar to reported results of CCL forces measured in vivo in goats.

Animals↗
PubMed1983

Effect of tortuous extracellular pathways on resistance measurements.

There are many instances in which we are limited to measuring macroscopic quantities such as a bulk flow or an average field. In biology, wer are frequently interested in using such macroscopic measurements, for example, the total current from a tissue, to determine the microscopic properties of the cells or tubules of the tissue. The microstructure of the tissue will generally increase the resistance to flow over what would be measured in an unstructured medium. This paper derives a fairly general expression for the relationship between effective resistance to macroscopic flow and the specific resistance of the medium conducting the microscopic flow. This expression, called a tortuosity factor, is defined entirely in terms of measurable morphometric and geometric parameters of the tissue.

Animals↗
PubMed2026

Country specific hybridization of honey bees from lineage M.

BACKGROUND: Honey bees are essential pollinators supporting agricultural production and wild plant diversity. In evolutionary lineage M, some populations are threatened by genetic erosion caused by the widespread introduction of commercially bred queens. To assess this risk, wing images from existing and new datasets were used to assign them to four evolutionary lineages (A, C, M, and O). The new dataset consisted of 29,043 wing images representing 1,342 colony samples from ten countries. RESULTS: Overall, 63.7% of colonies belonged to lineage M, whereas 27.5% were classified as A, 7.9% as C, and 0.8% as O. Lineage M remains prevalent in unprotected populations in Portugal, Spain, and Ireland, as well as in protected populations elsewhere. In contrast, a pronounced decline was observed in unprotected populations in northeastern Poland. CONCLUSIONS: These findings reveal strong regional differences in the persistence of lineage M and underscore the need for coordinated conservation efforts throughout Europe. The data provided in this study should allow for more accurate discrimination between native and introduced phenotypes.

Apis mellifera↗
PubMed1991

Additive effects of dietary protein and energy deficiencies on diaphysis and bone tissue of rat femurs as determined by bending tests.

The present study was designed to study the effects of diets moderately restricted in protein and/or carbohydrate derived calories on morphometric parameters (geometric properties) and mechanical performance of both diaphysis (structural properties) and cortical bone tissue (material properties) from growing rat femurs, as determined by bending tests at low strain rates. Male rats aged 30 days were divided in four groups, namely NN = normal protein and energy, NPLE = normal protein and low energy, LP = low protein and normal energy, and LPLE = low protein and low energy. Each group was fed on a corresponding diet for 20 days. Both body weight and femoral length were greater in NN and lower in LL than in LE and LP groups. Geometrical and structural variables (with the exception of wall/lumen ratio) grossly paralleled changes in body weight, while material properties showed independent and less significant changes. Therefore, the assayed levels of restriction of either plastic or energetic nutrients seemed to alter bone biomechanics proportionally to the way it affected bone growth.

Animals↗
PubMed1997

Morphometric evaluations of personalised 3D reconstructions and geometric models of the human spine.

In the past, several techniques have been developed to study and analyse the 3D characteristics of the human spine: multi-view radiographic or biplanar 3D reconstructions, CT-scan 3D reconstructions and geometric models. Extensive evaluations of three of these techniques that are routinely used at Sainte-Justine Hospital (Montréal, Canada) are presented. The accuracy of these methods is assessed by comparing them with precise measurements made with a coordinate measuring machine on 17 thoracic and lumbar vertebrae (T1-L5) extracted from a normal cadaveric spine specimen. Multi-view radiographic 3D reconstructions are evaluated for different combinations of X-ray views: lateral (LAT), postero-anterior with normal incidence (PA0 degree) and postero-anterior with 20 degrees angled down incidence (PA20 degrees). The following accuracies are found for these reconstructions obtained from different radiographic setups: 2.1 +/- 1.5 mm for the combination with PA0 degree-LAT views, and 5.6 +/- 4.5 mm for the PA0 degree-PA20 degrees stereopair. Higher errors are found in the postero-anterior direction, especially for the PA0 degree-PA20 degrees view combination. Pedicles are found to be the most precise landmarks. Accuracy for CT-scan 3D reconstructions is about 1.1 +/- 0.8 mm. As for a geometric model built using a multiview radiographic reconstruction based on six landmarks per vertebra, accuracies of about 2.6 +/- 2.4 mm for landmarks and 2.3 +/- 2.0 mm for morphometric parameters are found. The geometric model and 3D reconstruction techniques give accurate information, at low X-ray dose. The accuracy assessment of the techniques used to study the 3D characteristics of the human spine is important, because it allows better and more efficient quantitative evaluations of spinal dysfunctions and their treatments, as well as biomechanical modeling of the spine.

Evaluation Studies as Topic↗
PubMed2006

Facial patterns in Cercopithecoidea and Hominoidea: a geometric approach.

The maxillofacial and orbital compartments of the primate skull contribute to the ontogenetic and phylogenetic variability of the viscerocranium and are of crucial evolutionary relevance. As the form of organisms changes depending on endo- and exogenous factors, metrical evaluation of specific adaptations and incorporation of the results into a biological framework could be helpful in identifying valid characters for separation of taxa (e.g. family, genus, and species) and in understanding divergence and convergence. During the last two decades a morphometric "revolution" heralded by Rohlf & Marcus (1993), Adams et al. (2004) and Oxnard (2004) brought about a synthesis of traditional quantitative-morphometrical with modern methods. This approach is called "Geometric Morphometrics (GM)" and constitutes the coremethod applied here. Based on standardized photographs (in Norma frontalis), landmarks (LM) were set and two-dimensional coordinates (X, Y) recorded for the facial cranium in selected representatives of the superfamilies Cercopithecoidea and Hominoidea. The comparison of two datasets by means of factor analysis and distance computation for the complete maxillofacial complex on the one hand, and circumorbital and orbital features on the other, indicate that morphological differences between super-families and genera are valid for separating them even in a heterogeneous sample like the one presented here. Including more landmarks and therewith capturing the morph in a more complex way optimizes separation within the sample.

Algorithms↗
PubMedDate not supplied

Morphometric analysis of sonographic images by spatial geometric modeling.

A methodology able to derive spatial geometric models from input sequences of sonographic slices is proposed. The developed modeling procedure can be utilized to perform computer-assisted anatomic 3D analysis both on all echo space and selected subregions. The modeling procedure is mainly composed of three sequential phases: a) automatic acquisition and preprocessing of time sequences of 2D echotomograms; b) 3D reconstruction of images and computing of discrete distance maps of selected echoes according to predefined projective laws; and c) generation of a spatial geometric model of the examined object starting from the previously computed maps.

Algorithms↗
PubMed2002

Morphometrics and the role of the phenotype in studies of the evolution of developmental mechanisms.

Developmental mechanisms are usually assumed to evolve by natural selection of the morphological traits they produce. Therefore, information on phenotypic traits is an important component of comparative studies of development. Morphometrics permits the rigorous quantitative analysis of variation in organismal size and shape, and is increasingly being used in developmental contexts. The new methods of morphometrics combine a geometric concept of shape with the procedures of multivariate statistics, and constitute a powerful and flexible set of tools for analyzing morphological variation. This paper briefly reviews these methods and provides examples of their application in studies of genetic variation and developmental modularity. The results of morphometric analyses can be readily interpreted in relation to the geometry and anatomical structure of the parts under study. Genetic studies of shape in the mouse mandible found two recurrent patterns in environmental and genetic variation from different origins, suggesting that the development system 'channels' the phenotypic expression of variation in similar ways. Moreover, by analyzing the correlations of left-right asymmetries of morphometric traits, it is possible to delimit the spatial extent of developmental modules. These methods complement the experimental approaches of developmental biology and genetics, and can be expected to be especially fruitful in combination with them.

Animals↗
PubMed2026

Skull morphology of the extinct Tasmanian tiger suggests unique biting style.

The recently extinct thylacine (Tasmanian tiger) was the largest modern marsupial predator. It is considered a classic example of evolutionary convergence due to striking similarities with placental canids (e.g., foxes and wolves), particularly in the skull, despite ~160 million years of evolutionary separation. However, we here present geometric and linear morphometric evidence that the thylacine's cranial form arises from a mosaic of traits not represented among canids or other living mammalian carnivores. Thylacines had disproportionately large heads, tall and gracile snouts with a flared canine region, and conspicuously large infraorbital foramina. Many of these traits suggest adaptations to fast, high-impact snapping behaviour in prey capture, as proposed for several living and extinct predatorial vertebrates with similar trait combinations. The thylacine's cranial function may therefore not be inferable from observation of living mammals. However, genomic progress presents new opportunities for future insights into the evolution and development of thylacine cranial adaptation.

Animals↗
PubMedDate not supplied

Evolutionary integration and morphological diversification in complex morphological structures: mandible shape divergence in spiny rats (Rodentia, Echimyidae).

The rodent mandible has become a paradigm for studies on the development and evolution of complex morphological structures. We use a combination of geometric and multivariate morphometric methods in order to assess the correspondence between integration patterns and a priori biological models in the context of evolutionary shape divergence in the mandible of rodents of the family Echimyidae. The correlation of shape distances among operational taxonomic units (individuals, species, genera) in separate morphogenetic components allowed the construction of integration matrices among mandible components for data sets corresponding to varying levels of genetic divergence (intergeneric, interspecific, and intrapopulational). The integration matrices were associated with a priori biological (developmental, genetical, modular) models, and the maximum integration axes (singular warps) were compared with realized axes of maximum interspecific variation (relative warps). The integration pattern and intensity were not stable in data sets with different levels of genetic divergence, and the varying functional demands during the ecological radiation in the family were probably responsible for the differences in observed integration patterns. Developmental and genetic models were significantly associated with the interspecific integration patterns observed, suggesting a role for neutral evolution during the evolutionary divergence of mandible shape. However, directional and stabilizing selection were not discarded as processes responsible for the generation of interspecific integration. The choreography of the morphogenetic components in the mandible is highly flexible and the integrated groups of components can be reorganized depending on functional demands during evolutionary shape changes.

Animals↗
PubMedDate not supplied

[The morphometric characteristics of the nonpyramidal neurons in field CA1 of the human hippocampus].

The content of lipofuscin is different in pyramidal and nonpyramidal neurons (NpNH) of the pyramidal layer of the field CA1 of the brain hippocampus of adult man. This criterion allowed using the method of intracellular administration of Lucifer yellow for staining NpNH only. The morphometrical analysis of geometrical parameters and orientation of the dendrites allowed all the NpNH to be divided into 4 types: large multipolar spine-free neurons, middle-sized multipolar spine-free neurons, middle-sized multipolar neurons with short dendrites and small bipolar reticular neurons.

Aged↗
PubMed2005

A morphometric, neuroanatomical, and behavioral study on the effects of geometric constraint on the growing brain: the methyl 2-cyanoacrylate craniosynostosis model.

OBJECT: The effects of premature sutural synostosis on the developing brain remain unknown. A model of craniosynostosis in the perinatal rat was used to investigate the morphological and cytoarchitectural changes in the maturing brain as well as the neurobehavioral outcome. METHODS: A total of 56 perinatal rats, eight in each subgroup, were used in this study. Hypothermic arrest was induced in the rats and methyl 2-cyanocrylate was applied across the sagittal, coronal, and lambdoidal sutures at postnatal Days 0, 3, and 7. Sham rats underwent similar hypothermic arrest and application of methyl 2-cyanoacrylate but at a site different from the sutural lines. Age-matched rats that did not undergo any procedure were included as normal controls. Serial gross measurements were obtained to chart calvarial growth and computerized tomography scanning was performed to calculate mean calvarial volumes. At postnatal Day 30, the brains were fixed in situ and detailed morphological and cytoarchitectural analysis was conducted. There were no statistical differences in any of the analyses between sham rats and normal age-matched controls. In contrast, calvarial growth rates (analysis of variance, p < 0.05), mean brain weights (t-test, p < 0.01), and anterior-posterior and lateral diameter measurements (t-test, p < 0.01) were different for all synostotic rats compared with sham controls. On cytoarchitectural surveys, focal areas of nodular heterotopia and differences in cell density at the pyramidal cell layer were noted (t-test, p < 0.01). Open field testing also demonstrated excessive exploratory behavior in the synostosed animals. CONCLUSIONS: Early pan-calvarial sutural synostosis in the perinatal rat after administration of methyl 2-cyanoacrylate is associated with morphometrical and cytoarchitectural changes in the developing brain.

Animals↗
PubMed2003

Mathematical description of geometric and kinematic aspects of smooth muscle plasticity and some related morphometrics.

Despite considerable investigation, the mechanisms underlying the functional properties of smooth muscle are poorly understood. This can be attributed, at least in part, to a lack of knowledge about the structure and organization of the contractile apparatus inside the muscle cell. Recent observations of the plasticity of smooth muscle and of morphometry of the cell have provided enough information for us to propose a quantitative, although highly simplified, model for the geometric arrangement of contractile units and their collective kinematic functions in smooth muscle, particularly airway smooth muscle. We propose that, to a considerable extent, contractile machinery restructures upon activation of the muscle and adapts to cell geometry at the time of activation. We assume that, under steady-state conditions, the geometric arrangement of contractile units and the filaments within these units determines the kinematic characteristics of the muscle. The model successfully predicts the results of experiments on airway smooth muscle plasticity relating to maximal force generation, maximal velocity of shortening, and the variation of compliance with adapted length. The model is also concordant with morphometric observations that show an increase in myosin filament density when muscle is adapted to a longer length. The model provides a framework for design of experiments to quantitatively test various aspects of smooth muscle plasticity in terms of geometric arrangement of contractile units and the muscle's mechanical properties.

Actins↗