Comparative growth in the olfactory system of the developing chick with considerations for evolutionary studies.

Despite the long-held assumption that olfaction plays a relatively minor role in the behavioral ecology of birds, crown-group avians exhibit marked phylogenetic variation in the size and form of the olfactory apparatus. As part of a larger effort to better understand the role of olfaction and olfactory tissues in the evolution and development of the avian skull, we present the first quantitative analysis of ontogenetic scaling between olfactory features [olfactory bulbs (OBs) and olfactory turbinates] and neighboring structures (cerebrum, total brain, respiratory turbinates) based on the model organism Gallus gallus. The OB develops under the predictions of a concerted evolutionary model with rapid early growth that is quickly overcome by the longer, sustained growth of the larger cerebrum. A similar pattern is found in the nasal cavity where the morphologically simple (non-scrolled) olfactory turbinates appear and mature early, with extended growth characterizing the larger and scrolled respiratory turbinates. Pairwise regressions largely recover allometric relationships among the examined structures, with a notable exception being the isometric trajectory of the OB and olfactory turbinate. Their parallel growth suggests a unique regulatory pathway that is likely driven by the morphogenesis of the olfactory nerve, which serves as a structural bridge between the two features. Still, isometry was not necessarily expected given that the olfactory epithelium covers more than just the turbinate. These data illuminate a number of evolutionary hypotheses that, moving forward, should inform tradeoffs and constraints between the olfactory and neighboring systems in the avian head.

Analysis of the development of human foetal nasal turbinates using CBCT imaging.

PURPOSE: The morphological structure of the nasal cavity (NC) is important for endoscopic surgical treatment. The location of nasal turbinates, including the superior turbinate (ST), middle turbinate (MT) and inferior turbinate (IT), are well presented during the formation of the human NC in cone beam CT (CBCT) images. There is a complex relationship between the nasal sinuses, the maxillary sinus (MS), ethmoidal sinus and sphenoid sinus, during formation of the NC structure at the morphological level. There is a need to clearly define the relationships of these nasal elements at the ossification level, during development. METHODS: We investigated the three-dimensional construction of human foetal NC elements, including ST, MT, IT and vomer, using CBCT images from 16 weeks gestation (E16) to E31 (25 foetuses) and compared it to histochemical observations (E25). RESULTS: At the stage of ossification, the studied elements are elongated in the posterior region near the sphenoidal bone, showing that the locations of the ST, MT, and IT are important during formation of the NC. CBCT analysis revealed that the horizontal and vertical directions of nasal turbinates affect the formation of the human NC. CONCLUSION: The location and elongated development of the MT is one of the most important elements for NC formation. The relationship between the nasal sinus and nasal turbine at the level of ossification may provide useful information in clinical treatment of children.

A Rare Concha Variation: Coronal Cleft.

Nasal turbinates are embryologically derived from a series of outgrowths from the foetal lateral nasal wall. These outgrowths form a series of ridges, referred to as "ethmoturbinals" and have several vital functions. Several different turbinate variations have been reported so far. The authors presented 3 patients of coronal clefted concha who were diagnosed with magnetic resonance imaging. Computed tomography scans and nasal endoscopic examinations are also performed subsequently. These patients are the first coronal clefted concha cases in the literature and also the first radiological study defining concha cleft. This shows paucity of data documenting variations in the lateral nasal wall. Understanding the anatomy and the anatomic variations of the nasal cavity and nasal turbinates is critical to guide the procedure due to its close proximity to vital structures such as orbita and skull base, especially for functional endoscopic sinus surgery that is a widely used technique nowadays.

Nasal, septal, and turbinate anatomy and embryology.

This article discusses the development and anatomy of the nasal septum and structures of the lateral nasal wall. Emphasis is placed on anatomic variations associated with surgically correctable nasal obstruction. Common variations, such as deviated nasal septum, inferior turbinate hypertrophy, paradoxic middle turbinate, and concha bullosa, are discussed. Rare developmental causes of nasal obstruction are briefly outlined.

[Fetal ventilation and craniomaxillary development]. / Ventilation foetale et développement cranio-maxillaire.

Data acquired by means of color Doppler ultrasound very explicitly suggest what the role of the fetal ventilation and nasal capsules in the morphogenesis of the maxillary prognathism, turbinates, nasal valves and nasopharynx could be. Furthermore, the dysmorphologies observed in Apert or Crouzon craniosynostosis, achondroplasia or unilateral cleft lip would also testify that the influence of the fetal ventilatory dynamics goes beyond the limits of the face and extends to the cranial base and the cranium. The wealth of raised hypothesis thanks to the contribution of this imaging system could question the validity of some conceptions of the fetal craniomaxillary morphogenesis.

The forgotten turbinate: the role of the superior turbinate in endoscopic sinus surgery.

The fate of the middle turbinate in endoscopic sinus surgery has been a subject of debate for some time. The superior turbinate's role, however, has been largely passed over. Past anatomic descriptions and illustrations have given surgeons the incorrect impression that this structure is well superior and out of the field of dissection. Injury to the superior turbinate may account for postoperative hyposmia. The superior turbinate also serves as a constant landmark for the sphenoethmoidal recess, and a limited resection allows the surgeon to identify and include the natural ostium of the sphenoid sinus in the sphenoidotomy. The embryology and anatomy of the superior turbinate are reviewed. An approach to the natural ostium of the sphenoid sinus from the lateral side of the middle turbinate, using the superior turbinate as a guide, is described.

Oxidative stress in cells infected with bovine viral diarrhoea virus: a crucial step in the induction of apoptosis.

Bovine viral diarrhoea virus (BVDV) belongs to the genus Pestivirus of the family Flaviviridae. Both a noncytopathic (ncp) and an antigenically related cytopathic (cp) BVDV can be isolated from persistently infected animals suffering from mucosal disease. In every case studied so far, the genomic changes leading to the cp biotype correlate with the production of the NS3 nonstructural protein, which, in the ncp biotype, is present in its uncleaved form, NS23. This report shows that, in contrast to ncp BVDV, the cp biotype induces apoptosis in cultured embryonic bovine turbinate cells. Early in the process of apoptosis, cells show a rise in the intracellular level of reactive oxygen species, which is indicative of oxidative stress. This precedes two hallmarks of apoptosis, caspase activation as shown by cleavage of the caspase substrate poly(ADP-ribose) polymerase, and DNA fragmentation. Cells were protected from apoptosis only by certain antioxidants (butylated hydroxyanisole and ebselen), whereas others (N-acetylcysteine, pyrrolidine dithiocarbamate, lipoic acid, dihydrolipoic acid and tiron) turned out to be ineffective. Antioxidants that protected cells from apoptosis prevented oxidative stress but failed to block virus growth. These observations suggest that oxidative stress, which occurs early in the interaction between cp BVDV and its host cell, may be a crucial event in the sequence leading to apoptotic cell death. Hence, apoptosis is not required for the multiplication of the cp biotype of BVDV.

A banded topography in the developing rat's olfactory epithelial surface.

In situ hybridization studies from various laboratories have shown that the rat's olfactory epithelium has four distinct regions in which most putative odor receptors are located. To determine whether morphological features accompany this biochemical patterning, olfactory epithelial surfaces of rat nasal endoturbinates and septa were examined with scanning electron microscopy, placing particular emphasis on endoturbinate IIb. There was some morphological patterning at embryonic day 15 (E15), but distinct regions were not yet discernible. Regionalization became distinct at E16 and E18. Posterior regions (Regions 1 and 2) had much higher receptor cell knob densities than more anterior regions closer to the respiratory epithelium (Regions 3 and 4). Supporting cell microvilli were longer in Region 1 than in Region 2. Apices of cells surrounding the receptor cells were flatter in Regions 1 and 2 than in Regions 3 and, especially, Region 4. In Regions 1-3, these surrounding cells were made up mainly of supporting cells; in Region 4 they included respiratory cells. Regions 3 and 4 also had glandular openings and scattered microvillous cells that resemble hair cells of the ear. Older fetuses and adults showed similar evidence of patterning, but detailed examination was precluded by the increased length and entanglement of receptor cell cilia and supporting cell microvilli. In conclusion, a distinct topographic pattern, involving both receptor and surrounding cells, emerges during development of the rat olfactory epithelial surface. Location of the bands roughly matches the zones seen by in situ hybridization.

The embryonic development of the human ethmoid labyrinth from 8-40 weeks.

The embryonic development of the human ethmoid labyrinth was studied in 24 fetal heads aged between 8 and 40 weeks of gestation under light microscopy. The uncinate process was identifiable at 8 weeks of gestation on the laterosuperior portion of the inferior turbinate; however, at this stage of development, the ethmoid bulla was not apparent. The ethmoid bulla developed on the lateral wall of the middle meatus by 12 weeks of gestation. By 14 weeks, the primordial ethmoid infundibulum and primordial maxillary sinus were seen developing between the uncinate process and the ethmoid bulla. It was obvious that the anterior and middle ethmoid cells developed from the ethmoid bulla. By 22 weeks of gestation, the first cell of the anterior ethmoid group was evident in the anterior-inferior portion of the ethmoid bulla. By 23 weeks of gestation, the first cell of the middle ethmoid group was visible in the superior portion of the ethmoid bulla. Pneumatization of the middle turbinate occurred as part of normal development of the ethmoid labyrinth. By 32 weeks of gestation, the ostium for the development of the middle turbinate cell was seen in the superior-interior portion of the middle turbinate. These observations provide new insight into the development of the ethmoid labyrinth and have important implications for the understanding of normal anatomy and developmental variants of the ethmoid labyrinth.

Histological investigations of the nasal mucosa in human fetuses.

The adult nasal mucosa has been exposed to various external agents and selected physiological conditions. Changes in intranasal airflow influenced the morphological appearance of the mucosa. Studies of agents on the fetal mucosa and its development may contribute to better understanding of the morphology of the nasal mucosa. The authors studied the nasal mucosa of 20- to 26-week-old fetuses using light microscopy and scanning and transmission electron microscopy. Findings showed that this developing nasal mucosa took part in the production and movement of mucus in the nasal cavity.

Cells resembling hair cells in developing rat olfactory and nasal respiratory epithelia.

A hitherto ignored microvillous cell type, distinct from microvillous supporting cells and other microvillous cell types, was encountered in olfactory and respiratory epithelia of nasal turbinates of rat fetuses, near the transition between these two epithelia. The apex of the cell resembles the apices of vestibular hair cells. The cell has a cone-shaped bundle of microvilli, resembling the complex bundle of hair-cell stereocilia, accompanied by a cilium. Therefore we called this cell type the nasal hair cell. Cilium and microvilli seemed adhered. Cell numbers were very low, up to about 5 per turbinate. The cell's appearance is precocious compared to that of olfactory receptor and supporting cells. Also, while the apices of olfactory receptor and supporting cells and of ciliated respiratory cells underwent major morphological maturation during the developmental period from embryonic day 16 to day 21, the apical structures of the nasal hair cell only changed marginally from embryonic day 16, when they were first seen, through to at least embryonic day 21. The cell's location and precociously mature appearance suggests that it plays a special role in the development of nasal epithelia.

Morphogenesis of the lateral nasal wall from 6 to 36 weeks.

This research describes the development of the lateral nasal wall, the description of which will allow a better comprehension of its anatomic complexity. One hundred embryos and fetuses from the sixth to thirty-sixth weeks of morphologic age were studied. The seventh week shows the first buds of the three turbinates. At the ninth week the precartilaginous nucleus of the inferior turbinate is observed. Likewise, at the tenth week the uncinate process appears, and the invagination of the epithelium begins the formation of the infundibulum and the maxillar sinus. At the fourteenth week the cartilaginous nasal capsule is present. The epithelium is invaginated, starting the formation of the ethmoid cells. During the seventeenth week of development the invagination of the mucus has invaded the maxillar bone, which constitutes the maxillar sinus. At the thirty-sixth week the lateral nasal wall is well developed. In 23 fetuses the supreme turbinate (fourth) was found. Although the length of the lower three turbinates increased progressively and proportionally in intrauterine life without differences between the sexes, the fourth remains invariably at an average length of 5 mm from the fourteenth to the thirty-sixth and was present in 65% of male fetuses.

The embryonic development of the lateral nasal wall from 8 to 24 weeks.

This histological study of 20 fetal heads aged between 8 and 24 weeks of gestation demonstrates and describes the embryonic development of the lateral wall of the nose. The three turbinates (inferior, middle, and superior) arise as soft-tissue swellings (preturbinates) by 8 weeks' gestation. A cartilage capsule surrounds the nose at 8 weeks and by 9 weeks, medially directed flanges of cartilage have invaded all three preturbinates. The uncinate process arises from the medial surface of the lateral cartilaginous capsule and is first identifiable by 10 weeks. An "air space" progressively develops from 11 to 12 weeks lateral to the cartilaginous uncinate process and from this space, the embryonic channel to the maxillary sinus develops. The embryonic woven bone of the maxilla can be identified from 9 to 10 weeks and enlarges both absolutely and relatively to the nasal cavity, so that by 13 to 14 weeks, this expanding bone forms the lateral wall of the inferior meatus as the cartilaginous nasal capsule regresses.

[Prenatal development of connective and supportive tissue in the inferior nasal concha of man]. / Die pränatale Entwicklung der Binde-und Stützgewebe in der unteren Nasenmuschel des Menschen.

At histological sections of 16 human noses from the 3rd fetal month up to the newborn stage the continuous increase of collagen structures in the connective and holding tissue aging of the inferior nasal concha were investigated with conventional histological, polarisationsoptical and histochemical technics. It was stated that from the 3rd up to the 5th fetal month a mesenchyme in the process of changing is present and in the 5th fetal month a fibre texture like in adults can be seen. The ossification of the chondral frame work of the concha to a double lamella begins in the 5th fetal month, but isn't completely finished in the newborn. The concentration of neutral polysaccharides and glycosaminoglycanes increases with the onset of fiber formation and ossification.