Organization of the Olfactory and Respiratory Skeleton in the Nose of the Gray Short-Tailed Opossum Monodelphis domestica

The internal nasal skeleton in Monodelphis domestica, the gray short-tailed opossum, primarily supports olfactory and respiratory epithelia, the vomeronasal organ, and the nasal gland. This scaffold is built by the median mesethmoid, and the paired vomer and ethmoid bones. The mesethmoid ossifies within the nasal septum cartilage. The bilateral ethmoid segregates respiratory and olfactory regions, and its geometry offers insight into the functional, developmental, and genomic organization of the nose. It forms through partial coalescence of separate elements known as turbinals, which in Monodelphis comprise the maxilloturbinal, nasoturbinal, five endoturbinals, and two ectoturbinals. Geometry of the ethmoid increases respiratory mucosal surface area by a factor of six and olfactory mucosal surface by nearly an order of magnitude. Respiratory epithelium warms and humidifies inspired air, recovers moisture as air is exhaled, and may help mediate brain temperature. In contrast, the olfactory skeleton functions as a series of small funnels that support growth of new olfactory neurons throughout life. Olfactory mucosa lines the mouth of each funnel, forming blind olfactory recesses known as the ethmoid cells, and neuronal axons are funneled from the epithelium through tiny olfactory foramina in the cribriform plate, into close proximity with target glomeruli in the olfactory bulb of the brain where each axon makes its first synapse. The skeleton may thus mediate topological correspondence between odorant receptor areas in the nose with particular glomeruli in the olfactory bulb, enabling growth throughout life of new olfactory neurons and proper targeting by their axons. The geometric arrangement of odorant receptors suggests that a measure of volatility may be a component in the peripheral olfactory code, and that corresponding glomeruli may function in temporal signal processing. Supporting visualizations for this study are available online at www.DigiMorph.org.     

Auditory anatomy of beaked whales and other odontocetes: Potential for cochlear stimulation via a “vibroacoustic duct mechanism”

Computed tomography (CT) and microcomputed tomography (microCT) were used to examine the structures involved in cochlear stimulation in odontocetes and terrestrial mammals. Cranial CT examined the osseous attachment of the skull to the tympanoperiotic complex (TPC) and the path of the endocranial foramen of the vestibulocochlear nerve (EFVN), which was assumed to contain the perilymphatic duct. Additional CTs of TPC were taken postextraction to examine the gross morphology of this structure. MicroCT was used to examine the acoustic windows of the cochlea, including the round and oval windows and the apertures of the cochlear and vestibular aqueducts. Cranial CT scans demonstrated an osseous connection between the skull and TPC in beaked whales and Physeter macrocephalus. EFVN traveled through a greater length of cranial bone and communicated more closely with the periotic bone in beaked whales than in other species. Ziphius cavirostris was observed to have a reduced medial sulcus of the mallear ridge (MSMR) and tympanic plate and an enlarged aperture of the cochlear aqueduct, respectively. The potential significance of these findings, including the role of the perilymphatic duct as a novel route of cochlear stimulation referred to as the “vibroacoustic duct mechanism,” are discussed.     

Palatine bone in human cyclopia

In human cyclopia, a maxillopalatine mass separates the median orbit from the oral cavity. The palatine component of this bony mass has been studied in serial sections through the median third of the head in three perinatal human specimens presenting with a median orbit and proboscis. One head was sectioned in the sagittal plane and two in the coronal plane. The course of each neurovascular bundle arising from the maxillary artery and nerve was used to facilitate the identification of the various parts of the palatine bone. The data obtained were used to outline the palatine component of the maxillopalatine mass as it presented on the inferior aspect of a dried cyclops skull. The suggestion is made that the abnormalities of the palatine bone in human cyclopia are secondary to the absence of the presphenoid and the nasal cavity.     

鼻内镜下鼻中隔软骨、筛骨垂直板或耳屏软骨修补鼻中隔穿孔

目的:探讨鼻内镜下应用颞肌筋膜包裹自体鼻中隔软骨、筛骨垂直板或耳屏软骨修补鼻中隔穿孔的临床疗效。方法:回顾性分析2007年8月至2014年8月我院17例行鼻内镜下鼻中隔穿孔修补术患者的临床资料,所有患者术前均行鼻内镜及副鼻窦CT检查,术中分别采用颞肌筋膜包裹自体鼻中隔软骨、筛骨垂直板或带软骨膜的自体耳屏软骨,形成骨性支架,修补鼻中隔穿孔。术后均予抗生素抗感染,并用碱性成纤维细胞生长因子凝胶涂抹创面,促进周边黏膜向穿孔处生长。结果:17例患者均一次修复成功,术后1~2月穿孔处被黏膜完全覆盖,鼻中隔正常解剖结构得以恢复,随访1~3年无再次穿孔,鼻中隔穿孔产生的临床症状术后改善明显。结论:鼻内镜下应用鼻中隔软骨、筛骨垂直板或耳屏软骨修补鼻中隔穿孔安全、有效、简便,值得推广。     

Quantitative observations on the nasal epithelia and olfactory innervation in bats. Suggested design mechanisms for the olfactory bulb.

The nasal epithelia of two species of bats were quantified with respect to relative surface areas and olfactory epithelial volumes. In the macrosmatic Aribeus jamaicensis 55.9% of the nasal cavity surface was covered by olfactory epithelium (232.4 mm2), in contrast to only 28.9% in the microsmatic Myotis lucifugus (36.4 mm2). The roles of the various nasal epithelia have been discussed as they may relate to olfaction, respiration and echolocation. In the olfactory bulbs of both species, the estimated concentration of mitral cells approximated at 2,500/mm2 compared to an olfactory nerve concentration of 5/mm2. In Artibeus, calculated total volume of olfactory epithelium was on the order of 16 times greater than in Myotis, and Artibeus' olfactory bulb diameter was twice as great. These findings, together with previously published surface, volume and physiological relationships, suggest a developmental design mechanism for an olfactory bulb in which the number of olfactory receptors increases some 450-fold above an initially established ratio of 2:1 between receptors and mitral cells. Key governing factors could be requisite mechanical rigidity of the cribriform plate of the ethmoid bone and response thresholds of higher brain centers.     

Enamel Ultrastructure in Fossil Cetaceans (Cetacea: Archaeoceti and Odontoceti)

The transition from terrestrial ancestry to a fully pelagic life profoundly altered the body systems of cetaceans, with extreme morphological changes in the skull and feeding apparatus. The Oligocene Epoch was a crucial time in the evolution of cetaceans when the ancestors of modern whales and dolphins (Neoceti) underwent major diversification, but details of dental structure and evolution are poorly known for the archaeocete-neocete transition. We report the morphology of teeth and ultrastructure of enamel in archaeocetes, and fossil platanistoids and delphinoids, ranging from late Oligocene (Waitaki Valley, New Zealand) to Pliocene (Caldera, Chile). Teeth were embedded in epoxy resin, sectioned in cross and longitudinal planes, polished, etched, and coated with gold palladium for scanning electron microscopy (SEM) observation. SEM images showed that in archaeocetes, squalodontids and Prosqualodon (taxa with heterodont and nonpolydont/limited polydont teeth), the inner enamel was organized in Hunter-Schreger bands (HSB) with an outer layer of radial enamel. This is a common pattern in most large-bodied mammals and it is regarded as a biomechanical adaptation related to food processing and crack resistance. Fossil Otekaikea sp. and delphinoids, which were polydont and homodont, showed a simpler structure, with inner radial and outer prismless enamel. Radial enamel is regarded as more wear-resistant and has been retained in several mammalian taxa in which opposing tooth surfaces slide over each other. These observations suggest that the transition from a heterodont and nonpolydont/limited polydont dentition in archaeocetes and early odontocetes, to homodont and polydont teeth in crownward odontocetes, was also linked to a marked simplification in the enamel Schmelzmuster. These patterns probably reflect functional shifts in food processing from shear-and-mastication in archaeocetes and early odontocetes, to pierce-and-grasp occlusion in crownward odontocetes, with the implication of less demanding feeding biomechanics as seen in most extant odontocetes.     

The ‘Unicorn’ Dinosaur That Wasn’t: A New Reconstruction of the Crest of Tsintaosaurus and the Early Evolution of the Lambeosaurine Crest and Rostrum

The lambeosaurine Tsintaosaurus spinorhinus has traditionally been reconstructed with an elevated, hollow, spike-like crest composed entirely of the nasal bones, although this has been disputed. Here, we provide a new reconstruction of the skull of this species based on reexamination and reinterpretation of the morphology and articular relationships of the type and Paratype skulls and a fragmentary crest. We confirm the presence of a supracranial crest composed of the elevated nasal bones, but also including the premaxillae. We hypothesize that the crest is a tall, lobate, hollow structure that projects dorsally and slightly caudally a distance greater than the height of the skull along the quadrate. In our reconstruction, the nasal passage passes through the crest, but enters the skull rostral to the tubular process of the nasals, not through it. Tsintaosaurus spinorhinus is rediagnosed on the basis of a suite of cranial autapomorphies including a circumnarial fossa subdivided into three accessory fossae, prefrontal with ascending rostral process and lateral flange, nasals fused sagittally to form elongate tubular process that rises dorsally from skull roof, each nasal being expanded rostrocaudally into a rhomboid distal process, and medial processes of premaxillae at the summit of the cranial crest inserted between rhomboid processes of nasals. Tsintaosaurus spinorhinus lacks characters that are present in more derived lambeosaurines (parasaurolophins and lambeosaurins), such as rotation of the caudal margin of the crest to an acute angle with the skull roof, lateral processes of the nasals that enclose part of the intracranial cavity and participate in the formation of the walls of the common median chamber, and a smooth narial fossa lacking ridges and accessory fossae. We hypothesize that ancestrally the rostrum of lambeosaurines may have been more similar to that in Saurolophinae, and became subsequently reduced in complexity during evolution of the group.     

Localization of choline acetyltransferase and vasoactive intestinal polypeptide-like immunoreactivity in the nervus terminalis of the fetal and neonatal rat

Ganglia of the nervus terminalis have been shown to contain luteinizing hormone-releasing hormone (LHRH) immunoreactive cells in several mammalian species. These cells are always accompanied by clusters of cells non-immunoreactive to antiserum to LHRH. Using immunocytochemical procedures, we found choline acetyltransferase (ChAT) and vasoactive intestinal polypeptide (VIP) present in cell bodies and in nerve processes throughout the peripheral, intracranial and central projections of the nervus terminalis. In addition, a dense plexus of substance P (SP) immunoreactive fibers was seen in the nasal mucosa surrounding the nasal glandular acini and blood vessels. A number of SP reactive fibers were traced with the olfactory nerves through the cribriform plate of the ethmoid bone and appeared to enter the brain in the area of the central roots of the nervus terminalis.     

Esthesioneuroblastoma: treatment of skull-base recurrence

Thirty-nine patients with esthesioneuroblastoma are reviewed. The presentation of the tumor, symptomatology, investigation, and treatment are discussed. A recommended treatment regimen is outlined. Histologic typing is valueless in predicting tumor behavior. An illustrative and difficult case of recurrent base of skull esthesioneuroblastoma is presented. The resection performed is described, and the problem of extradural oropharyngeal communication is discussed. The solution was to use a temporalis and galeal frontalis flap. Reconstruction was with an external and intraoral prosthesis. Optimal treatment in a fresh lesion is radical surgery with or without radiation therapy. Esthesioneuroblastoma is a rare and often misdiagnosed malignant tumor of the olfactory epithelium. Originally described by Bergen et al. in 1924 as "esthesioneuroepithelioma olfactif," it was introduced into the North American literature by Schall and Lineback in 1951. Since then, fewer than 200 cases have been collected. The various terms used to describe it--olfactory esthesioneuroblastoma, esthesioneurocytoma, and olfactory neuroblastoma--all denote origin from the neural crest. The sensory nerves of smell are short bundles of fibers that originate in the olfactory bulb and pass through the cribriform plate to the olfactory area of the nasal mucosa. This mucosa is located in the most superior part of both nasal fossae. Thus the usual primary sites of occurrence include the superior nasal cavity or nasal septum, and turbinates, the ethmoid, or the cribriform plate, although an extranasal site of origin has been suggested. Symptoms are usually progressive and range from nasal obstruction or epistaxis to diplopia, ocular pain, and headaches in the more advanced disease state.(ABSTRACT TRUNCATED AT 250 WORDS)     

Scaling of mammalian ethmoid bones can predict olfactory organ size and performance

The relation between size and performance is central for understanding the evolution of sensory systems, and much interest has been focused on mammalian eyes and ears. However, we know very little about olfactory organ size (OOS), as data for a representative set of mammals are lacking. Here, we present a cranial endocast method for estimating OOS by measuring an easily accessible part of the system, the perforated part of the ethmoid bone, through which the primary olfactory axons reach the olfactory bulb. In 16 species, for which relevant data are available, the area of the perforated ethmoid bone is directly proportional to the area of the olfactory epithelium. Thus, the ethmoid bone is a useful indicator enabling us to analyse 150 species, and describe the distribution of OOS within the class Mammalia. In the future, a method using skull material may be applied to fossil skulls. In relation to skull size, humans, apes and monkeys have small olfactory organs, while prosimians have OOSs typical for mammals of their size. Large ungulates have impressive olfactory organs. Relating anatomy to published thresholds, we find that sensitivity increases with increasing absolute organ size.     

THE DISCOVERY OF THE CRIBRIFORM PLATE IN SINOCONODON YOUNCI (TRICONODONTA,MAMMALIA)

ThepresenceofacribriformplateinlivingplacentalsandthemarsupialsandabsenceinmonotremesmayimplythatmammalsarediphyleticandtheoriginofcribriformplatetookplacewithinthcMammalia.Buttheconc1usioncamefromthe1ivingmammalsonly,andhasnotbeensupportedbypalaeontologicalevidence.Itsappearanceinoneoftheoldestandthemostprimitivemammals,Sinoconodon,possiblysuggeststhatthecribriformplatemayoccurearlier,i.e.inthetimeofthetransitionfromtheadvancedmammal-likereptiles,Cynodontia,tothetruemammals,andthatthedistrib…     

Comparative morphology and evolution of the otic region in toothed whales (Cetacea, Mammalia)

The otic region in the skull of archeocetes and odontocetes is compared and interpreted with special emphasis on the morphology and suspension of the ear bones. In archeocetes, the periotic was obviously separate from the mastoid but still integrated within the skull via a long anterior and posterior process. The rotation of the cochlear part of the periotic was already obvious. The tympanic bone was attached to a decreasing number of neighboring elements, with the periotic becoming more and more important in the later archeocetes. The accessory air sacs of the tympanic cavity had invaded some of the adjacent skeletal elements and attained a moderate-to-remarkable extension. In the evolution of the odontocetes, the periotic and tympanic were successively uncoupled from the skull and combined to a new morphological and functional unit (tympanoperiotic complex). This uncoupling was mainly achieved by shortening the periotical processes and simultaneously extending the tympanic air sacs. For functional reasons, however, the periotic (posterior process) stayed in immediate contact with the mastoid, the latter remaining in the lateral wall of skull. In advanced marine dolphins, the bony sheaths of the accessory air sacs are largely reduced, presumably because of volume fluctuations in the tympanic cavity during diving. The perfect uncoupling of the ear bones from the skull obviously was an essential prerequisite for directional hearing, for effective ultrasound orientation and communication, and finally, for the striking development of the dolphin brain.     

Reconstructing Body Size in Extinct Crown Cetacea (Neoceti) Using Allometry,Phylogenetic Methods and Tests from the Fossil Record

Living cetaceans exhibit interspecific size ranging across several orders of magnitude, and rank among the largest vertebrates ever. Details of how cetaceans evolved different body sizes, however, remain obscure, because they lack basic morphological proxies that have been traditionally used in other fossil vertebrates. Here, we reconstruct the body size of extinct crown group cetaceans (Neoceti) using different regression methods on extant skull and length data, in a phylogenetic context. Because most fossil cetaceans are fragmentary, we developed regression equations to predict total length based on cranial metrics that are preserved on most fossil crania. The resultant regression equations are based on a database of skull and length data from most extant lineages of cetaceans (n = 45 species; 272 specimens), sampling all living mysticete genera and all major clades of odontocetes. In generating predictive equations, we compared both conventional species data regression and independent contrast regression methods, as well as single trait predictors and a new approach that combines the advantages of a partial least squares (PLS) multivariate regression with independent contrasts. This last approach leverages the predictive power of using multiple correlated proxies. Lastly, we used the rare occurrences of fossil cetaceans with preserved total lengths to test the performance of our predictive equations for reconstructing body size from skull measurements alone. Our results demonstrate that incorporating information about phylogenetic relationships and multiple cranial measures in PLS scaling studies increases the accuracy of reconstructed body size, most notably by reducing prediction intervals by more than 70%. With this empirical foundation, we highlight the outline of major features in the evolution of body size for Neoceti and future opportunities to use these metrics for paleobiological questions.     

Head morphology in perinatal dolphins: a window into phylogeny and ontogeny

In this paper on the ontogenesis and evolutionary biology of odontocete cetaceans (toothed whales), we investigate the head morphology of three perinatal pantropical spotted dolphins (Stenella attenuata) with the following methods: computer-assisted tomography, magnetic resonance imaging, conventional X-ray imaging, cryo-sectioning as well as gross dissection. Comparison of these anatomical methods reveals that for a complete structural analysis, a combination of modern imaging techniques and conventional morphological methods is needed. In addition to the perinatal dolphins, we include series of microslides of fetal odontocetes (S. attenuata, common dolphin Delphinus delphis, narwhal Monodon monoceros). In contrast to other mammals, newborn cetaceans represent an extremely precocial state of development correlated to the fact that they have to swim and surface immediately after birth. Accordingly, the morphology of the perinatal dolphin head is very similar to that of the adult. Comparison with early fetal stages of dolphins shows that the ontogenetic change from the general mammalian bauplan to cetacean organization was characterized by profound morphological transformations of the relevant organ systems and roughly seems to parallel the phylogenetic transition from terrestrial ancestors to modern odontocetes.     

Morphological variation among the inner ears of extinct and extant baleen whales (Cetacea: Mysticeti)

Living mysticetes (baleen whales) and odontocetes (toothed whales) differ significantly in auditory function in that toothed whales are sensitive to high‐frequency and ultrasonic sound vibrations and mysticetes to low‐frequency and infrasonic noises. Our knowledge of the evolution and phylogeny of cetaceans, and mysticetes in particular, is at a point at which we can explore morphological and physiological changes within the baleen whale inner ear. Traditional comparative anatomy and landmark‐based 3D‐geometric morphometric analyses were performed to investigate the anatomical diversity of the inner ears of extinct and extant mysticetes in comparison with other cetaceans. Principal component analyses (PCAs) show that the cochlear morphospace of odontocetes is tangential to that of mysticetes, but odontocetes are completely separated from mysticetes when semicircular canal landmarks are combined with the cochlear data. The cochlea of the archaeocete Zygorhiza kochii and early diverging extinct mysticetes plot within the morphospace of crown mysticetes, suggesting that mysticetes possess ancestral cochlear morphology and physiology. The PCA results indicate variation among mysticete species, although no major patterns are recovered to suggest separate hearing or locomotor regimes. Phylogenetic signal was detected for several clades, including crown Cetacea and crown Mysticeti, with the most clades expressing phylogenetic signal in the semicircular canal dataset. Brownian motion could not be excluded as an explanation for the signal, except for analyses combining cochlea and semicircular canal datasets for Balaenopteridae. J. Morphol. 277:1599–1615, 2016. © 2016 Wiley Periodicals, Inc.     

L’origine et l’histoire évolutive des Cétacés

Cetaceans are the most highly modified mammals. They originate among terrestrial ariodactyles during the Early Eocene. The oldest known cetacean is Pakicetus, a terrestrial and cursorial taxon of the Early Eocene (50 Ma), which entered the water in search for food or, possibly, to protect its skin from the sun. A few million years later, Ambulocetus is an amphibious cetacean capable of moving on land but also an agile swimmer using its hind limbs for propulsion. Ambulocetus was a formidable predator with powerful teeth. The nares of Pakicetus and Ambulocetus were anteriorly placed, at the apex of the snout. During the Late Eocene, there appeared the first strictly aquatic cetaceans, the Basilosauridae. Their hind limbs are totally atrophied and are not functional. The nares are on the dorsal face of the rostrum on the anterior third of the skull. From that time, the way toward modern cetaceans was opened; the oldest mysticetes are from the Latest Eocene and the oldest odontocetes from the Early Oligocene.     

Morphology of the interorbital region of Saimiri sciureus

The skull of the platyrrhine primate Saimiri sciureus is distinguished by a large interorbital fenestra. Juvenile skulls still show a bony interorbital septum with some small gaps. A morphogenetic study was undertaken to better understand the structures of the interorbital region, which represents a linkage between the base of the braincase and the nasal skeleton. Already in early ontogenetic stages a reduction of the posterior portion of the nasal capsule and of the cartilaginous interorbital septum are observed, resulting in the formation of a primary interorbital fenestra. A bony interorbital septum is mainly formed in perinatal age stages by ossification of the presphenoid and by medial fusion of the frontals; the primary interorbital fenestra is retained as a small opening. It only occurs in late juvenile stages when the definitive interorbital fenestra develops by by secondary transformation of bone into a membrane of dense connective tissue; this process is most probably caused by mechanical friction of the very closely approximated eyes of both sides.     

Effects of Localized Hydrophilic Mannitol and Hydrophobic Nelfinavir Administration Targeted to Olfactory Epithelium on Brain Distribution

Many nasally applied compounds gain access to the brain and the central nervous system (CNS) with varying degree. Direct nose-to-brain access is believed to be achieved through nervous connections which travel from the CNS across the cribriform plate into the olfactory region of the nasal cavity. However, current delivery strategies are not targeted to preferentially deposit drugs to the olfactory at cribriform. Therefore, we have developed a pressurized olfactory delivery (POD) device which consistently and non-invasively deposited a majority of drug to the olfactory region of the nasal cavity in rats. Using both a hydrophobic drug, mannitol (log P = -3.1), and a hydrophobic drug, nelfinavir (log P = 6.0), and POD device, we compared brain and blood levels after nasal deposition primarily on the olfactory region with POD or nose drops which deposited primarily on the respiratory region in rats. POD administration of mannitol in rats provided a 3.6-fold (p < 0.05) increase in cortex-to-blood ratio, compared to respiratory epithelium deposition with nose drop. Administration of nelfinavir provided a 13.6-fold (p < 0.05) advantage in cortex-to-blood ratio with POD administration, compared to nose drops. These results suggest that increasing the fraction of drug deposited on the olfactory region of the nasal cavity will result in increased direct nose-to-brain transport.     

Does nasal echolocation influence the modularity of the mammal skull?

In vertebrates, changes in cranial modularity can evolve rapidly in response to selection. However, mammals have apparently maintained their pattern of cranial integration throughout their evolutionary history and across tremendous morphological and ecological diversity. Here, we use phylogenetic, geometric morphometric and comparative analyses to test the hypothesis that the modularity of the mammalian skull has been remodelled in rhinolophid bats due to the novel and critical function of the nasal cavity in echolocation. We predicted that nasal echolocation has resulted in the evolution of a third cranial module, the ‘nasal dome’, in addition to the braincase and rostrum modules, which are conserved across mammals. We also test for similarities in the evolution of skull shape in relation to habitat across rhinolophids. We find that, despite broad variation in the shape of the nasal dome, the integration of the rhinolophid skull is highly consistent with conserved patterns of modularity found in other mammals. Across their broad geographical distribution, cranial shape in rhinolophids follows two major divisions that could reflect adaptations to dietary and environmental differences in African versus South Asian distributions. Our results highlight the potential of a relatively simple modular template to generate broad morphological and functional variation in mammals.     

Intranasal volume and olfactory function

The aim of this exploratory study was to identify the volume intranasal segments as they relate to parameters of olfactory function. Fifty healthy male volunteers (age range 22-59 years, mean age 28.5 years) were included. Olfactory function was measured by lateralized phenyl ethyl alcohol odor thresholds and odor discrimination, and by bilateral odor identification. Magnetic resonance imaging of the nasal cavity was performed immediately following olfactometry. To correlate the results of olfactometry with intranasal volume, each nasal cavity was divided into 11 segments. Significant correlations were found between the odor thresholds and volumes of the anterior part of the lower and upper meatus of the right nasal cavity. These results reveal that two nasal segments are important for inter-individual differences of odor thresholds in healthy subjects: (i) the segment in the upper meatus below the cribriform plate and (ii) the anterior segment of the inferior meatus. The latter finding is of special interest for nasal surgery, which allows modification of this volume through resection of the inferior turbinate and/or septoplasty.