Mammalian face as an evolutionary novelty Higashiyama, Hiroki; Koyabu, Daisuke; Hirasawa, Tatsuya ...
Proceedings of the National Academy of Sciences - PNAS,
11/2021, Letnik:
118, Številka:
44
Journal Article
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The anterior end of the mammalian face is characteristically composed of a semimotile nose, not the upper jaw as in other tetrapods. Thus, the therian nose is covered ventrolaterally by the ..."premaxilla," and the osteocranium possesses only a single nasal aperture because of the absence of medial bony elements. This stands in contrast to those in other tetrapods in whom the premaxilla covers the rostral terminus of the snout, providing a key to understanding the evolution of the mammalian face. Here, we show that the premaxilla in therian mammals (placentals and marsupials) is not entirely homologous to those in other amniotes; the therian premaxilla is a composite of the septomaxilla and the palatine remnant of the premaxilla of nontherian amniotes (including monotremes). By comparing topographical relationships of craniofacial primordia and nerve supplies in various tetrapod embryos, we found that the therian premaxilla is predominantly of the maxillary prominence origin and associated with mandibular arch. The rostral-most part of the upper jaw in nonmammalian tetrapods corresponds to the motile nose in therian mammals. During development, experimental inhibition of primordial growth demonstrated that the entire mammalian upper jaw mostly originates from the maxillary prominence, unlike other amniotes. Consistently, cell lineage tracing in transgenic mice revealed a mammalian-specific rostral growth of the maxillary prominence. We conclude that the mammalian-specific face, the muzzle, is an evolutionary novelty obtained by overriding ancestral developmental constraints to establish a novel topographical framework in craniofacial mesenchyme.
Abstract Objectives The purpose of this study was to evaluate four in-house optimized, non-contrast enhanced sequences for MRI-investigation of maxillo-mandibular and dental structures by use of 3 T. ...Methods 12 volunteers with different dental status were examined by using a 3 T MRI with a 20-channel standard head-and-neck coil. All images performed were evaluated by using 3D-techniques, with different slice-thicknesses, in 3D T1- and T2-weighted sequences, as well as by using new techniques of image depictions. In addition phantom measurements were performed to estimate the extent of image artefacts caused by retainers and metal implants. Results Mean age of the participants was 33 years (range, 25.5–62.75 years), and the sex ratio was 5 females to 7 males. We identified different techniques to improve osseous and dental structures, despite problems caused by dental implants, tooth crowns or braces. Conclusion The sequences evaluated offered excellent visualization in 2D and 3D of osseous and dental structures. Anatomical, osseous and dental structures were described at their ROI, in relation to patients with dental and head and neck pathologies. The ability to detect and distinguish pathological processes as soon as possible in 3D with excellent image quality avoiding ionizing radiation remains a challenging domain.
Introduction The purpose of this study was to determine the accuracy and reliability of 3-dimensional craniofacial measurements obtained from cone-beam computed tomography (CBCT) scans of a dry human ...skull. Methods Seventeen landmarks were identified on the skull. CBCT scans were then obtained, with 2 skull orientations during scanning. Twenty-nine interlandmark linear measurements were made directly on the skull and compared with the same measurements made on the CBCT scans. All measurements were made by 2 operators on 4 separate occasions. Results The method errors were 0.19, 0.21, and 0.19 mm in the x-, y- and z-axes, respectively. Repeated measures analysis of variance (ANOVA) showed no significant intraoperator or interoperator differences. The mean measurement error was –0.01 mm (SD, 0.129 mm). Five measurement errors were found to be statistically significantly different; however, all measurement errors were below the known voxel size and clinically insignificant. No differences were found in the measurements from the 2 CBCT scan orientations of the skull. Conclusions CBCT allows for clinically accurate and reliable 3-dimensional linear measurements of the craniofacial complex. Moreover, skull orientation during CBCT scanning does not affect the accuracy or the reliability of these measurements.
For accurate interpretation of magnetic resonance (MR) images of the equine brain, knowledge of the normal cross‐sectional anatomy of the brain and associated structures (such as the cranial nerves) ...is essential. The purpose of this prospective cadaver study was to describe and compare MRI and computed tomography (CT) anatomy of cranial nerves' origins and associated skull foramina in a sample of five horses. All horses were presented for euthanasia for reasons unrelated to the head. Heads were collected posteuthanasia and T2‐weighted MR images were obtained in the transverse, sagittal, and dorsal planes. Thin‐slice MR sequences were also acquired using transverse 3D‐CISS sequences that allowed mutliplanar reformatting. Transverse thin‐slice CT images were acquired and multiplanar reformatting was used to create comparative images. Magnetic resonance imaging consistently allowed visualization of cranial nerves II, V, VII, VIII, and XII in all horses. The cranial nerves III, IV, and VI were identifiable as a group despite difficulties in identification of individual nerves. The group of cranial nerves IX, X, and XI were identified in 4/5 horses although the region where they exited the skull was identified in all cases. The course of nerves II and V could be followed on several slices and the main divisions of cranial nerve V could be distinguished in all cases. In conclusion, CT allowed clear visualization of the skull foramina and occasionally the nerves themselves, facilitating identification of the nerves for comparison with MRI images.
Analysing photonic structures in plants Vignolini, Silvia; Moyroud, Edwige; Glover, Beverley J. ...
Journal of the Royal Society interface,
10/2013, Letnik:
10, Številka:
87
Journal Article
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The outer layers of a range of plant tissues, including flower petals, leaves and fruits, exhibit an intriguing variation of microscopic structures. Some of these structures include ordered periodic ...multilayers and diffraction gratings that give rise to interesting optical appearances. The colour arising from such structures is generally brighter than pigment-based colour. Here, we describe the main types of photonic structures found in plants and discuss the experimental approaches that can be used to analyse them. These experimental approaches allow identification of the physical mechanisms producing structural colours with a high degree of confidence.
Anthropometric Analysis of the Face Zacharopoulos, Georgios V; Manios, Andreas; Kau, Chung H ...
The Journal of craniofacial surgery,
01/2016, Letnik:
27, Številka:
1
Journal Article
Recenzirano
Facial anthropometric analysis is essential for planning cosmetic and reconstructive facial surgery, but has not been available in detail for modern Greeks. In this study, multiple measurements of ...the face were performed on young Greek males and females to provide a complete facial anthropometric profile of this population and to compare its facial morphology with that of North American Caucasians.
Thirty-one direct facial anthropometric measurements were obtained from 152 Greek students. Moreover, the prevalence of the various face types was determined. The resulting data were compared with those published regarding North American Caucasians.
A complete set of average anthropometric data was obtained for each sex. Greek males, when compared to Greek females, were found to have statistically significantly longer foreheads as well as greater values in morphologic face height, mandible width, maxillary surface arc distance, and mandibular surface arc distance. In both sexes, the most common face types were mesoprosop, leptoprosop, and hyperleptoprosop. Greek males had significantly wider faces and mandibles than the North American Caucasian males, whereas Greek females had only significantly wider mandibles than their North American counterparts.
Differences of statistical significance were noted in the head and face regions among sexes as well as among Greek and North American Caucasians. With the establishment of facial norms for Greek adults, this study contributes to the preoperative planning as well as postoperative evaluation of Greek patients that are, respectively, scheduled for or are to be subjected to facial reconstructive and aesthetic surgery.
Despite being among the most celebrated taxa from Cambrian biotas, anomalocaridids (order Radiodonta) have provoked intense debate about their affinities within the moulting-animal clade that ...includes Arthropoda. Current alternatives identify anomalocaridids as either stem-group euarthropods, crown-group euarthropods near the ancestry of chelicerates, or a segmented ecdysozoan lineage with convergent similarity to arthropods in appendage construction. Determining unambiguous affinities has been impeded by uncertainties about the segmental affiliation of anomalocaridid frontal appendages. These structures are variably homologized with jointed appendages of the second (deutocerebral) head segment, including antennae and 'great appendages' of Cambrian arthropods, or with the paired antenniform frontal appendages of living Onychophora and some Cambrian lobopodians. Here we describe Lyrarapax unguispinus, a new anomalocaridid from the early Cambrian Chengjiang biota, southwest China, nearly complete specimens of which preserve traces of muscles, digestive tract and brain. The traces of brain provide the first direct evidence for the segmental composition of the anomalocaridid head and its appendicular organization. Carbon-rich areas in the head resolve paired pre-protocerebral ganglia at the origin of paired frontal appendages. The ganglia connect to areas indicative of a bilateral pre-oral brain that receives projections from the eyestalk neuropils and compound retina. The dorsal, segmented brain of L. unguispinus reinforces an alliance between anomalocaridids and arthropods rather than cycloneuralians. Correspondences in brain organization between anomalocaridids and Onychophora resolve pre-protocerebral ganglia, associated with pre-ocular frontal appendages, as characters of the last common ancestor of euarthropods and onychophorans. A position of Radiodonta on the euarthropod stem-lineage implies the transformation of frontal appendages to another structure in crown-group euarthropods, with gene expression and neuroanatomy providing strong evidence that the paired, pre-oral labrum is the remnant of paired frontal appendages.
The relationship of the skin, the superficial and deep fat compartments, and the ligaments that connect these structures is key to performing any rhytidectomy. In order to successfully mobilize, ...elevate, and reposition the facial soft tissues, a detailed understanding of facial anatomy is required. This article details the anatomy of the midface and neck that is essential to understanding and performing the face-lift operation.
Fossil Evidence on Origin of the Mammalian Brain Rowe, Timothy B.; Macrini, Thomas E.; Luo, Zhe-Xi
Science (American Association for the Advancement of Science),
05/2011, Letnik:
332, Številka:
6032
Journal Article
Recenzirano
Many hypotheses have been postulated regarding the early evolution of the mammalian brain. Here, x-ray tomography of the Early Jurassic mammaliaforms Morganucodon and Hadrocodium sheds light on this ...history. We found that relative brain size expanded to mammalian levels, with enlarged olfactory bulbs, neocortex, olfactory (pyriform) cortex, and cerebellum, in two evolutionary pulses. The initial pulse was probably driven by increased resolution in olfaction and improvements in tactile sensitivity (from body hair) and neuromuscular coordination. A second pulse of olfactory enhancement then enlarged the brain to mammalian levels. The origin of crown Mammalia saw a third pulse of olfactory enhancement, with ossified ethmoid turbinals supporting an expansive olfactory epithelium in the nasal cavity, allowing full expression of a huge odorant receptor genome.
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