The Rhinal Bone and Its Evolutionary Significance

Bjerring, H. C. (Section of Palaeozoology, Swedish Museum of Natural History, Stockholm, Sweden.) The rhinal bone and its evolutionary significance. Zool. Scripta 1 (5): 193–201, 1972.– On the basis of serially sectioned embryos of Amia calva, the ethmoidal region of the endocranium and certain adjacent exo-skeletal elements are analysed. The results include evidence of the existence of branchial moieties pertaining to the first or premandibular metamere. Each of these moieties comprises infrapharyngobranchial (the ethmobasal), suprapharyngobranchial (the orbitonasal lamina), and epibranchial (the palatoquadrate pterygoid process) endoskeletal components as well as horizontal infrapharyngeal (the vomer), ascending infrapharyngeal (the rhinal), and epal (the dermopalatines and ectopterygoid) dental plates. The anterior cerebral arteries may represent the efferent blood vessels of the first-metamere branchial moieties. A hypothesis on the origin of the nasal sacs is offered.      

Development of the ethmoidal structures of the endocranium in Discoglossus pictus (Anura: Discoglossidae)

We use histological techniques and computer‐aided three‐dimensional reconstructions made from serial histological sections to describe the ontogeny of the ethmoidal endocranium of discoglossid frog Discoglossus pictus. We identify a pattern of development for the suprarostral cartilage that differs from previous findings and probably represents the ancestral anuran pattern. The nasal cartilages, including the inferior prenasal cartilage, are de novo adult structures. The only larva‐derived structures of the adult nasal capsules are the posterior aspects of the solum nasi and septum nasi. We also identify patterns of development for the ethmoid plate and postnasal wall that occur during early in ontogenesis. These patterns are associated with development events during metamorphic climax. The pattern of timing of chondrification of the anterior nasal cartilages more closely coincides with that of the neobatrachian species than that recorded for the pelobatid frog Spea. In addition, this study supports a sister taxon relationship between Discoglossus and Alytes. J. Morphol. 271:1078‐1093, 2010. © 2010 Wiley‐Liss, Inc.     

The Nerve Supply to the Second Metamere Basicranial Muscle in Osteolepiform Vertebrates,with Some Remarks on the Basic Composition of the Endocranium

The endocranium of Devonian osteolepiforms includes four minor structures, called zygals, which probably represent cephalic vertebral elements belonging to the second, third, and fourth metameres. Also, the endocranium exhibits a partial segmentation in the form of vestiges of intrametameric articulations attributable to the anterior five metameres. Finally, the basicranial muscle of osteolepiforms, extending across the lower part of the endocranial articulation within the second metamere, is possibly supplied by a separate cranial nerve, for which the term nervus rarus is proposed. This hypothetical cranial nerve, which in osteolepiforms possibly emerges from the endocranium through a canal in the fourth metamere, is suggested to constitute, together with the trochlear nerve, the somatic motor component of the second cranionerval segment.     

Anuran postnasal wall homology: An experimental extirpation study

The nasal placode was extirpated unilaterally in Gosner stage 18–20 embryos of Rana sylvatica, R. palustris and R. pipiens, in order to test alternative proposed schemes of homology for the ethmoidal attachment of the palatoquadrate in anurans and urodeles. Absence of the nasal sac has no pronounced effect on the formation of larval chondrocranial structures. In contrast, in metamorphosed animals the lamina orbitonasalis and inferior prenasal process are the only nasal capsule structures present on the operated side. The medial nasal branch of the deep ophthalmic nerve passes forward over the dorsal surface of the lamina orbitonasalis, rather than through an orbitonasal foramen. Comparison with previous experimental work on urodeles supports the traditional homology of the anuran lamina orbitonasalis with the antorbital process of urodeles and other vertebrates. J. Morphol. 238:343–353, 1998. © 1998 Wiley-Liss, Inc.     

Anatomy,histology, and histochemistry of the olfactory organ of the Korean shuttles mudskipper Periophthalmus modestus

The Korean shuttles mudskipper Periophthalmus modestus has paired olfactory organs on its snout, consisting of anterior and posterior nostrils, a single olfactory canal with sensory and nonsensory epithelia, and a single accessory nasal sac. Its sensory epithelium consists of numerous islets forming a pseudostratified layer and contains various cells: olfactory receptor neurons, supporting cells, basal cells, lymphatic cells (LCs), and axon bundles. The sensory epithelium is a stratified squamous layer comprising stratified epithelial cells, mucous cells (MCs) with glycogen, flattened cells (FCs), LCs, and unidentified cells. Specific structures are as follows: (a) a tubular anterior nostril projecting outward, (b) a slit posterior nostril, (c) an elongated olfactory canal, (d) an ethmoidal accessory nasal sac, (e) axon bundles found only in the basal layer of the sensory epithelium, (f) FCs only at the top of the nonsensory epithelium, and (g) glycogen-containing MCs. Such structures seem to be unique in that they have not been observed in most teleost fishes spending their whole life in water.     

Beyrichosteus radiatus n. g., n. sp., ein brachythoraker Arthrodire mit vollständig verknöchertem Endokranium aus dem höheren Mittel-Devon (Givetium) der Eifel

A completely perichondrally ossified endocranium of a generalized reprsentative of the Eubrachythoraci,Beyrichosteus radiatus n. g., n. sp., is described. The specimen shows a typical platybasie skull with widely separated nasal capsules like that of the mainly Early Devonian Dolichothoraci. This is contrary to the spezialized generaTapinosteus andPholidosteus from Wildungen, being previously often regarded as model for the endocranium of coccosteomorph arthrodires. However, characters of the orbit and the nasal capsule are more similar to other Eubrachythoraci than to those of Dolichothoraci and primitive Brachythoraci. Until now, there are not enough other examples of sufficiently preserved endocrania of brachythoracid arthrodires known for a phylogenetic analysis. Nevertheless, the observations made onBeyrichosteus are questioning the assignment of the Pholidosteidae to the Coccosteomorphi.     

Ethmoidal arteries: origin, course, regions supplied and anastomoses]

The origin, course and regions supplied by the ethmoidal arteries were studied on 30 injected adult heads. After branching off, the anterior ethmoidal artery normally makes a single smooth loop by first coursing forwards and then, reversing itself towards the anterior ethmoidal foramen, it goes into the canal portion, likewise without bend or angularity. Occasionally, a common ethmoidal artery or a common source for the ethmoidal arteries is present. Very rarely does the artery fail entirely. As a rule, the posterior ethmoidal artery arises from the ophthalmic artery. Occasionally, however, it is missing or can even very rarely arise from the A. meningea media. The artery usually crosses over the superior oblique muscle while the anterior ethmoidal artery usually goes under the same muscle. In the fossa olfactoria, the ethmoidal arteries give off their most important dura and bone branches in the anterior cranial fossa and then continue into the walls of the cavum nasi. The courses and variations along with ipsi- and contralateral anastomoses are likewise demonstrated.     

The phyllolepid placoderm Cowralepis mclachlani: Insights into the evolution of feeding mechanisms in jawed vertebrates

Remarkably preserved specimens of Cowralepis mclachlani Ritchie, 2005 (Proc Linn Soc NSW 126:215–259) (Phyllolepida, Placodermi) represent a unique ontogenetic sequence adding to our understanding of anatomy, function, and phylogeny among basal jawed vertebrates (gnathostomes). A systematic review demonstrates that the Phyllolepida are a subgroup of the Arthrodira. Consideration of visceral and neurocranial characters supports the hypothesis that placoderms are the sister group to remaining gnathostomes. Placoderms possess, as adult plesiomorphic features, a number of characters that are only seen in the development of extant gnathostomes—a peramorphic shift relative to placoderms. Developmental evidence in vertebrates leads to a revised polarity of character transitions. These include 1) hyomandibula‐neurocranium and ventral parachordal‐palatoquadrate articulations (vertebrate synapomorphies); 2) jointed pharynx, paired basibranchials, anterior ethmoidal‐palatoquadrate articulation, short trabeculae cranii, and anterior and posterior neurocranial fissures (gnathostome synapomorphies); and 3) fused basibranchials, dorsal palatoquadrate‐neurocranium articulation, loss of the anterior neurocranial fissure, elongated trabeculae cranii, and transfer of the ventral parachordal‐palatoquadrate articulation to the trabeculae (crown group gnathostomes). The level of preservation in C. mclachlani provides the basis for a reinterpretation of phyllolepid anatomy and function. Cowralepis mclachlani possesses paired basibranchials allowing the reinterpretation of the visceral skeleton in other placoderms. Mandible depression in C. mclachlani follows an osteichthyan pattern and the ventral visceral skeleton acts as a functional unit. Evidence for hypobranchial musculature demonstrates the neural crest origin of the basibranchials and that Cowralepis was a suction feeder. Finally, the position of the visceral skeleton relative to the neurocranium in placoderms parallels the condition in selachians and osteichthyans, but differs in the elongation of the occiput. The cucullaris fossa of placoderms (interpreted as a site of muscle attachment) is shown to represent, in part, the parabranchial chamber. J. Morphol., 2009. © 2009 Wiley‐Liss, Inc.     

Cone Beam Computed Tomography Assessment of the Maxillary Incisive Canal and Foramen: Considerations of Anatomical Variations When Placing Immediate Implants

IntroductionThe maxillary incisive canal connects the roof of the oral cavity with the floor of nasal cavity and has the incisive and nasal foramina respectively at its two opposite ends. Its close proximity with the anterior incisors affects one’s ability to place immediate implants in ideal position.ObjectiveTo avoid causing complication, variations in their dimensions were studied.ResultsThe mean labiopalatal and mesiodistal measurements of the incisive foramen were 2.80mm and 3.49 mm respectively, while the labiopalatal width of the nasal foramen was 6.06mm. The incisive canal was 16.33mm long and 3.85 mm wide. The anterior maxillary bone has an average thickness of 7.63 mm. The dimensions of the incisive foramen and incisive canal, and anterior maxillary bone thickness demonstrated gender differences with males showing greater values. The anterior maxillary bone thickness was affected by age but this difference was not observed in canal dimensions. The majority of subjects have a funnel shape-like incisive canal with the broader opening located at its superior. They seem to have a longer slanted-curve canal with one channel at its middle portion and a narrower incisive foramen opening than those reported elsewhere.ConclusionsThis study found that gender is an important factor that affected the characteristics of the IC and the amount of bone anterior to it. Male generally had bigger IC and thicker anterior bone. In addition, the anterior maxillary bone thickness was affected by aging, where it becomes thinner with increased age even though the subjects were fully dentate.     

Morphological Observations on the Exoskeletal Skull Roof of an Osteolepiform from the Carboniferous of Scotland

The morphology of the parietal shield of the Carboniferous osteolepiform Megalichthys laticeps is described. Of special note are the following features, none of which have hitherto been observed in other members of the group: each intertemporal section of the lateral-line canal system gives off a large, backwardly directed tube which enters the posterior part of the ipsilateral parietal bone where it becomes highly ramified; anterolaterally each intertemporal bone possesses an irregularly shaped and forwardly directed projection—the frontodermosphenotic process—which is traversed by the intertemporal section of the lateral-line canal system. In addition, evidence is offered that Megalichthys laticeps was equipped with a paired extratemporal bone as well as a tripartite extra-scapular series of exoskeletal elements; also, that the presence of the extratemporal bone most likely was correlated with the configuration of the subjacent part of the endocranium; and, finally, that no appreciable movement occurred between the anterior and posterior cranial divisions.     

Ontogeny of the partial secondary wall of the otoccipital region of the endocranium in prehatching Alligator mississippiensis (Archosauria, Crocodylia)

The ontogeny of the posterior otic and anterior occipital portions of the neural endocranium of prehatching Alligator mississippiensis was investigated by reconstruction from sectioned material. In Stage 6 of this species, in which the endochondral ossification of the otoccipital region of the neural endocranium is only in its very early stage, two bony outgrowths-laminae-are present at the external wall of the posterior portion of the neural endocranium. The anterior lamina arises from the external surface of the basal plate at the level of the posterior margin of the subcapsular process; the posterior lamina arises from the external surface of that portion of the pila occipitalis that forms the posteroventral wall of the metotic fissure. During ontogeny, both laminae lying in the anteroposterior sequence ossify in membrane, fuse together, grow laterodorsally, and fuse with the lateral wall of the lateral semicircular canal and the crista parotica. This lamina forms a new, secondary wall enclosing the posterior section of the otic capsule and contains the large external jugular foramen (or foramen vagi) in its basal portion. The laminae, designated lamina juxtaotica anterior and posterior (lamina juxtaotica when fused together), have not been recorded previously in crocodylians and are absent in all other Recent reptiles. From the functional point of view, the juxtaotic lamina 1) forms the margins of the external jugular foramen, and 2) forms the floor of the posterior section of the Eustachian tube. In birds, the structure called the metotic cartilage, which arises in ontogeny as an independent element, has a similar position as the juxtaotic lamina. However, the two structures differ in their developmental origins and their relation to the Eustachian tube and the ramus hyomandibularis of the facialis nerve. Moreover, there is no external jugular foramen in birds.     

Anatomy of the feeding apparatus of the nurse shark,Ginglymostoma cirratum

The anatomy of the feeding apparatus of the nurse shark, Ginglymostoma cirratum, was investigated by gross dissection and computer axial tomography. The labial cartilages, jaws, jaw suspension, muscles, and ligaments of the head are described. Palatoquadrate cartilages articulate with the chondrocranium caudally by short, laterally projecting hyomandibulae and rostrally by ethmoorbital articulations. Short orbital processes of the palatoquadrates are joined to the ethmoid region of the chondrocranium by short, thin ethmopalatine ligaments. In addition, various ligaments, muscles, and the integument contribute to the suspension of the jaws. When the mouth is closed and the palatoquadrate retracted, the palatine process of the palatoquadrate is braced against the ventral surface of the nasal capsule and the ascending process of the palatoquadrate is in contact with the rostrodorsal end of the suborbital shelf. When the mandible is depressed and the palatoquadrate protrudes slightly rostroventrally, the palatoquadrate moves away from the chondrocranium. A dual articulation of the quadratomandibular joint restricts lateral movement between the mandible and the palatoquadrate. The vertically oriented preorbitalis muscle spans the gape and is hypothesized to contribute to the generation of powerful crushing forces for its hard prey. The attachment of the preorbitalis to the prominent labial cartilages is also hypothesized to assist in the retraction of the labial cartilages during jaw closure. Separate levator palatoquadrati and spiracularis muscles, which are longitudinally oriented and attach the chondrocranium to the palatoquadrate, are hypothesized to assist in the retraction of the palatoquadrate during the recovery phase of feeding kinematics. Morphological specializations for suction feeding that contribute to large subambient suction pressures include hypertrophied coracohyoideus and coracobranchiales muscles to depress the hyoid and branchial arches, a small oral aperture with well‐developed labial cartilages that occlude the gape laterally, and small teeth. J. Morphol. 241:33–60, 1999. © 1999 Wiley‐Liss, Inc.     

Early development of chondrocranium in the tailed frog Ascaphus truei (Amphibia: Anura): Implications for anuran palatoquadrate homologies

Chondrocranial development in Ascaphus truei was studied by serial sectioning and graphical reconstruction. Nine stages (21–29; 9–18 mm TL) were examined. Mesodermal cells were distinguished from ectomesenchymal (neural crest derived) cells by retained yolk granules. Ectomesenchymal parts of the chondrocranium include the suprarostrals, pila preoptica, anterior trabecula, and palatoquadrate. Mesodermal parts of the chondrocranium include the orbital cartilage, posterior trabecula, parachordal, basiotic lamina, and otic capsule. Development of the palatoquadrate is as follows. The pterygoid process first connects with the trabecula far rostrally; their fusion progresses caudally. The ascending process connects with a mesodermal bar that extends from the orbital cartilage to the otic capsule, and forms the ventral border of the dorsal trigeminal outlet. This bar is the “ascending process” of Ascaphus adults; it is a neurocranial, not palatoquadrate structure. The basal process chondrifies in an ectomesenchymal strand running from the quadrate keel to the postpalatine commissure. Later, the postpalatine commissure and basal process extend anteromedially to contact the floor of the anterior cupula of the otic capsule, creating separate foramina for the palatine and hyomandibular branches of the facial nerve. Based on these data, and on comparison with other frogs and salamanders, the anuran anterior quadratocranial commissure is homologized with the pterygoid process of salamanders, the anuran basal process (=“pseudobasal” or “hyobasal” process) with the basal process of salamanders, and the anuran otic ledge with the basitrabecular process of salamanders. The extensive similarities in palatoquadrate structure and development between frogs and salamanders, and lacking in caecilians, are not phylogenetically informative. Available information on fossil outgroups suggests that some of these similarities are primitive for Lissamphibia, whereas for others the polarity is uncertain. J. Morphol. 231:63-100, 1997. © 1997 Wiley-Liss, Inc.     

Histological and carbohydrate histochemical studies of the nasal mucosa of sheep in Saudi Arabia with special reference to its glandular tissue

The histology and carbohydrate histochemistry of the nasal mucosa with attention to glandular tissue had been studied in 7 heads of sheep. Tissues were taken from vestibular region, septum at level of the alar fold, rostral portion of nasal conchae, caudal portion of nasal conchae, middle portion of septum and ethmoidal conchae region. Stratified squamous nonkeratinized epithelium was observed covering the vestibular region. The propria-submucosa of the nasal vestibule was richly permeated with glands having affinity for PAS and non-alcianophilic. The post-vestibular portion of the nasal cavity was lined by transitional epithelium and caudal to it, stratified columnar nonciliated epithelium was noticed. The respiratory epithelium covered the caudal half of the nasal conchae and the major portion of the septum as well as the recesses of the ethmoidal conchae. The glands associated with the respiratory mucosa were thick, coiled and tubular, containing both nonalcianophilic PAS positive and alcianophilic PAS positive cells. The olfactory mucosa covered the ethmoidal conchae and showed predominant serous glands. The results were discussed with that given for other mammals and in regard to the respiratory functions of the nasal mucosa.     

The anatomy of the palatoquadrate in the Lower Triassic Proterosuchus fergusi (Reptilia,Archosauromorpha) and its morphological transformation within the archosauriform clade

The anatomy of the palatoquadrate ossifications of the Lower Triassic archosauromorph Proterosuchus fergusi from South Africa is described. It consists of two ossifications, the epipterygoid and the quadrate, which were joined by cartilage in life. The margins of the cartilage are clearly indicated by ridges and grooves on the dorsal surface of the pterygoid. The epipterygoid ossification consists of two structures: the anteroposteriorly expanded basal portion and, dorsally from it, an extending, slender, ascending process. From the anterior margin of the basal portion of the epipterygoid, a plate‐like structure, herein called the lamina epipterygoidea anteromedialis, extends anteromedially to form the anterolateral wall of the cavum epiptericum. Comparisons with the similarly constructed embryonal and adult epipterygoid components of Sphenodon punctatus show that the anteromedial lamina of the epipterygoid of P. fergusi is an additional component of the epipterygoid of this species and that this lamina is absent in the former species. However, a structure in a topologically similar position to the anteromedial lamina of the epipterygoid of P. fergusi is present in the palatoquadrate of Alligator mississippiensis. In the latter species, the structure is called the lamina palatoquadrati anterior; it ossifies in membrane and forms the dorsolateral cover of the huge trigeminal ganglion. It is hypothesized here that the anteromedial lamina of the epipterygoid of P. fergusi and the anterior lamina of the palatoquadrate of A. mississippiensis are most probably homologous structures and are present in both the basal and one of the crown taxa of the archosauromorph clade, respectively.     

Nasal fossa malformations and paramedian facial cleft: new perspectives.

Choanal atresia may be associated with other cranio-facial malformations, including various degrees of nasal fossa malformation, and may be a part of paramedian facial clefts (as described by Tessier et al. [1977]). We identified five such cases with combined clinical elements corresponding to Tessier's paramedian facial cleft, including eyelid coloboma, mild to severe choanal and nasal fossa anomalies, ethmoidal hypoplasia and anterior skull base malformation, sometimes with proboscis lateralis and half-nose hypoplasia. These observations incited us, first, to elaborate a conception which accounts for the likely embryological mechanisms involved; second, to propose a new classification based on anatomical and pathogenic embryological considerations; and last, to propose the use of transpalatal approach to restore choanal permeability, since endonasal laser therapy is particularly dangerous in such cases.     

筛动脉及其分支、筛孔的显微解剖学研究

目的：从显微解剖学角度探讨筛动脉及其分支起源和走行。方法：采用固定和灌注过的成人头部标本25具50侧。显微镜下解剖筛动脉及其分支的起源和走行。观察并测量筛孔数目iDacryon点与筛前孔（DA）、筛中孔（DM）、筛后孔（DP）、视神经管眶口（DO）的距离,筛前后孔之间的距离（AP）,筛后孔与视神经管眶口之间的距离（PO）,对所得数据作统计分析。结果：筛前动脉主要起自04段,有36支（72．00％）,眶内段长（5．16±1．24）mm,管径为（0．56±0．17）mm;筛后动脉主要起自02段,有26支（56．52％）,眶内段长（9．08±2．29）mm,管径为（0．37±0．14）mm。筛孔数目以双孔最多（占54侧）,其次为三孔（占40侧）,单孔和四孔各占3侧。DA：（17．28±2．24）mm;DM：（25．46±2．74）mm;DP：（30．48±2．27）mm;DO：（36．26±2．32）mm;AP：（13．20±2．19）mm;PO：（5．78±2．17）mm。结论：获得了筛动脉及其分支起源和走行的显微解剖学数据,为影像诊断和神经外科、眼科等手术方案的制定以及介入治疗提供了解剖学依据。