ANATOMICAL VARIATIONS OF FORAMEN OVALE AND CLINICAL SIGNIFICANCE

INTRODUCTION: The foramen ovale is present in sphenoid bone which transmits the mandibular nerve, accessory meningeal artery, emissary vein and the lesser petrosal nerve. This study was conducted on a total 100 si MATERIALS & METHODS: des in 50 dry adult skulls. The shape of foramen will be determined by a visual examination. Margins of foramen were carefully observed for the abnormal bony outgrowths such as sharp bony projections (spine), small blunt bony projection (tubercle), bony plate and bony bar. We obs RESULTS: erved the variations in shape of foramen ovale. We found oval, almond, round, triangular, slit like and irregular shaped in 62%, 20%, 9%, 4%, 3% and 2% foramina ovale respectively. We also observed abnormal bony outgrowths in the foramen ovale like spines, tubercles, bony plate and bony bar. Abnormal bony bar was dividing the foramen ovale in 2 compartments (Anterior and Posterior). The preci CONCLUSIONS: se knowledge of variations of foramen ovale is of valuable contribution for neurosurgeons to development of new and different techniques to approach the middle cranial fossa. In our study we found , 100% tubercles and 80% spines were arising from anterior margin of foramen ovale. These ndings are important for neurosurgeons to approach middle cranial fossa via foramen ovale for neurosurgical and diagnostic procedures like percutaneous biopsy of cavernous sinus tumours, electroencephalographic analysis, microvascular decompression , percutaneous trigeminal rhizotomy and administration of anaesthesia to the mandibular nerve. Surgeons should avoid to go , close to the anterior margin of foramen ovale as spines and tubercles could interrupt the procedures.

The developmental relationship between teeth and dermal odontodes in the most primitive bony fish Lophosteus

The ontogenetic trajectory of a marginal jawbone of Lophosteus superbus (Late Silurian, 422 Million years old), the phylogenetically most basal stem osteichthyan, visualized by synchrotron microtomography, reveals a developmental relationship between teeth and dermal odontodes that is not evident from the adult morphology. The earliest odontodes are two longitudinal founder ridges formed at the ossification center. Subsequent odontodes that are added lingually to the ridges turn into conical teeth and undergo cyclic replacement, while those added labially achieve a stellate appearance. Stellate odontodes deposited directly on the bony plate are aligned with the alternate files of teeth, whereas new tooth positions are inserted into the files of sequential addition when a gap appears. Successive teeth and overgrowing odontodes show hybrid morphologies around the oral-dermal boundary, suggesting signal cross-communication. We propose that teeth and dermal odontodes are modifications of a single system, regulated and differentiated by the oral and dermal epithelia.

From scales to armour: scale losses and trunk bony plate gains in ray-finned fishes

Actinopterygians (ray-finned fishes) are the most diversified group of vertebrates and are characterized by a variety of protective structures covering their tegument, the evolution of which has intrigued biologists for decades. Paleontological records showed that the first mineralized vertebrate skeleton was composed of dermal bony plates covering the body, including odontogenic and skeletogenic components. Later in evolution, the exoskeleton of actinopterygian’s trunk was composed of scale structures. Although scales are nowadays a widespread tegument cover, some contemporary lineages do not have scales but bony plates covering their trunk, whereas other lineages are devoid of any such structures. To understand the evolution of the tegument coverage and particularly the transition between different structures, we investigated the pattern of scale loss events along actinopterygian evolution and addressed the functional relationship between the scaleless phenotype and the ecology of fishes. Furthermore, we examined whether the emergence of trunk bony plates was dependent over the presence or absence of scales. To this aim, we used two recently published actinopterygian phylogenies, one including > 11,000 species, and by using stochastic mapping and Bayesian methods, we inferred scale loss events and trunk bony plate acquisitions. Our results reveal that a scaled tegument is the most frequent state in actinopterygians, but multiple independent scale loss events occurred along their phylogeny with essentially no scale re-acquisition. Based on linear mixed models, we found evidence supporting that after a scale loss event, fishes tend to change their ecology and adopt a benthic lifestyle. Furthermore, we show that trunk bony plates appeared independently multiple times along the phylogeny. By using fitted likelihood models for character evolution, we show that trunk bony plate acquisitions were dependent over a previous scale loss event. Overall, our findings support the hypothesis that tegument cover is a key evolutionary trait underlying actinopterygian radiation.Impact SummaryRay-finned fishes (actinopterygians) are the most diverse vertebrate group in the world. The majority of these fishes possess scales as a protective shield covering their trunk. However, several lineages display a body armour composed of trunk bony plates or are devoid of any protective structures. The diversity and the transitions between different tegument coverage types have not been previously studied in an evolutionary framework. Here, we investigate which structure was present at the origin of ray-finned fishes and how the different phenotypes emerged through time.We show that a scaled tegument was the most widespread sate along ray-finned fish evolution, yet scale losses occurred multiple independent times, while acquiring scales again almost never happened. Moreover, we reveal that scaleless teguments most probably led species to change their ecology and colonise the floors of oceans and water bodies. The functional advantages of a scaleless tegument in a benthic environment are yet to be demonstrated, but the increased cutaneous respiration could be an explanation. We show that trunk bony plates also emerged independently multiple times along the evolution of ray-finned fishes but these armours protecting the trunk can only appear after a scale loss event. Therefore, while the acquisitions of trunk bony plates are phylogenetically independent, they need a “common ground” to emerge. All together, our findings provide evidence that the various tegument covers have contributed to the outstanding diversification of ray-finned fishes.

Dental ontogeny in the most primitive bony fish Lophosteus reveals the developmental relationship between teeth and dermal odontodes

Ontogenetic data obtained by synchrotron microtomography of a marginal jawbone of Lophosteus superbus (Late Silurian, 422 Million years old), the phylogenetically basalmost stem osteichthyan, reveal developmental relationships between teeth and ornament that are not obvious from the adult morphology. The earliest odontodes are two longitudinal founder ridges formed at the ossification center. Subsequent odontodes that are added lingually to the ridges turn into conical teeth and undergo cyclic replacement, while those added labially achieve a stellate appearance. The stellate odontodes deposited directly on the bony plate are aligned with the alternate files of the teeth. Successive odontodes overgrowing the labial tooth rows become tooth-like and the replacement teeth near to them are ornament-like. We propose that teeth and ornament are modifications of a single odontode system regulated and differentiated by the oral and dermal signals; signal cross-communication between the two domains can occur around the oral-dermal boundary.

Effect of Rough Surface Platforms on the Mucosal Attachment and the Marginal Bone Loss of Implants: A Dog Study

The preservation of peri-implant tissues is an important factor for implant success. This study aimed to assess the influence of the surface features of a butt-joint platform on soft-tissue attachment and bone resorption after immediate or delayed implant placement. All premolars and first molars of eight Beagle dogs were extracted on one mandible side. Twelve-weeks later, the same surgery was developed on the other side. Five implants with different platform surface configurations were randomly inserted into the post-extracted-sockets. On the healed side, the same five different implants were randomly placed. Implants were inserted 1 mm subcrestal to the buccal bony plate and were connected to abutments. The primary outcome variables were the supracrestal soft tissue (SST) adaptation and the bone resorption related to the implant shoulder. The SST height was significantly larger in immediate implants (IC95% 3.9–4.9 mm) compared to delayed implants (IC95% 3.1–3.5 mm). Marginal bone loss tended to be higher in immediate implants (IC95% 0.4–0.9 mm) than in delayed implants (IC95% 0.3–0.8 mm). Linear-regression analysis suggested that the SST height was significantly affected by the configuration of the platform (0.3–1.9 mm). Roughened surface platforms resulted in higher SST height when compared to machined surface platforms. Marginal bone loss was less pronounced in roughened designs.

Morphometric and morphologic study of Foramen Ovale in In Indian population

Background:The floor of middle cranial fossa shows several foramina through which vital neural and vascular structures pass. Thus, the knowledge of normal and variant anatomy of these foramina is important. One such foramen is Foramen ovale which allows the passage of certain important structures. Aims and Objective:This study also aimed to provide a base line data to neurosurgeons for easy and safe approach to middle cranial fossa. Thus, to fulfill the above, the morphometric and morphologic characteristics of the foramenovalewere studied and the observed metric and non-metric parameters were compared with those of previous studies. Materials and Methods:The study has been conducted on 160 adult non-pathological dry human skulls of unknown age and sex. Those parts of broken skulls were included in the study in which the area of Foramen ovale was intact. All the parameters were obtained by one observer only to avoid inter-observer error. The foramen ovale was identified and different metric and non-metric parameters were observed and measured. Results:The most common shape on both sides was noted to be transversely oval. Out of 160 skulls, 2 skulls (1.25%) showed accessory FO bilaterally. 4 skulls showed divided FO on left side. Out of 4, 2 skulls( 1.25%) were noted to have bony bar and in 2 skulls (1.25%) the main FO were divided by bony plate. Conclusion: The morphologic variations of Foramen Ovale in the form of accessory foramen and presence of bony bar / bony plate are common. This study will provide a baseline data as well as frequency of related variations in our population for a safer approach by the surgeons.

Morphometric and Topographic Study of Foramen Ovale in Indian Skulls

Foramen ovale is an important foramen for neurosurgeons and used for percutaneous trigeminal rhizotomy in trigeminal neuralgia. The present study was undertaken to study anatomic variations in appearance, dimensions of foramen ovale and its location in relation to the zygomatic arch. The study was conducted on 50 dry human skulls of known sex, available in the museum of Anatomy Dept. in G.S.V.M. Medical College, Kanpur. The shape of foramen ovale and presence of any accessory bony structure like spur, spine, tubercle or bony plate were observed on both sides. The length and width of foramen ovale and its distance from articular tubercle and the anterior root of Zygomatic Arch was measured on both sides. The metric data was statistically analysed for bilateral symmetry and sexual dimorphism. The shape of foramen ovale was typically oval in most of the skulls (66%). In 40% sides any accessory bony structure was not seen while bony plate in 45% sides, spine in 6% and bridge like bony septa dividing the foramen into two compartments in 2% was observed. The mean length and width of foramen ovale in male skulls was 7.50+/-0.90 mm and 4.20+/-0.70 mm and 7.7+/-1.00 mm and 3.9+/-0.80 mm in the female skulls. The mean distance of foramen ovale from articular tubercle on Zygomatic arch was 32.8 +/- 2.8 mm in males and 31.1 +/- 2.4 mm in females. The mean distance from anterior root of Zygomatic arch was 21.4 +/- 1.9 mm in males and 21.6 +/- 1.7 mm in females. There was no significant difference in measurements of various metric parameters between right and left sides of foramen ovale (p>0.05) but highly significant difference was observed between male and female dimensions of all metric parameters.(p<0.001). Thus the foramen ovale does not exhibit bilateral symmetry but the sexual dimorphism is evident. The data is helpful for surgical practices.

Trunk dental tissue evolved independently from underlying dermal bony plates but is associated with surface bones in living odontode-bearing catfish

Although oral dental tissue is a vertebrate attribute, trunk dental tissue evolved in several extinct vertebrate lineages but is rare among living species. The question of which processes trigger dental-tissue formation in the trunk remains open, and would shed light on odontogenesis evolution. Extra-oral dental structures (odontodes) in the trunk are associated with underlying dermal bony plates, leading us to ask whether the formation of trunk bony plates is necessary for trunk odontodes to emerge. To address this question, we focus on Loricarioidei: an extant, highly diverse group of catfish whose species all have odontodes. We examined the location and cover of odontodes and trunk dermal bony plates for all six loricarioid families and 17 non-loricarioid catfish families for comparison. We inferred the phylogeny of Loricarioidei using a new 10-gene dataset, eight time-calibration points, and noise-reduction techniques. Based on this phylogeny, we reconstructed the ancestral states of odontode and bony plate cover, and find that trunk odontodes emerged before dermal bony plates in Loricarioidei. Yet we discovered that when bony plates are absent, other surface bones are always associated with odontodes, suggesting a link between osteogenic and odontogenic developmental pathways, and indicating a remarkable trunk odontogenic potential in Loricarioidei.