The Olfactory Pigment. In: Beidler LM, editor. Olfaction. Berlin: Springer Berlin Heidelberg; 1971. pp. 59-74. [DOI: 10.1007/978-3-642-65126-7_3]

Olfactory epithelium and ontogeny of the nasal chambers in the bowhead whale (Balaena mysticetus)

In a species of baleen whale, we identify olfactory epithelium that suggests a functional sense of smell and document the ontogeny of the surrounding olfactory anatomy. Whales must surface to breathe, thereby providing an opportunity to detect airborne odorants. Although many toothed whales (odontocetes) lack olfactory anatomy, baleen whales (mysticetes) have retained theirs. Here, we investigate fetal and postnatal specimens of bowhead whales (Balaena mysticetus). Computed tomography (CT) reveals the presence of nasal passages and nasal chambers with simple ethmoturbinates through ontogeny. Additionally, we describe the dorsal nasal meatuses and olfactory bulb chambers. The cribriform plate has foramina that communicate with the nasal chambers. We show this anatomy within the context of the whole prenatal and postnatal skull. We document the tunnel for the ethmoidal nerve (ethmoid foramen) and the rostrolateral recess of the nasal chamber, which appears postnatally. Bilateral symmetry was apparent in the postnatal nasal chambers. No such symmetry was found prenatally, possibly due to tissue deformation. No nasal air sacs were found in fetal development. Olfactory epithelium, identified histologically, covers at least part of the ethmoturbinates. We identify olfactory epithelium using six explicit criteria of mammalian olfactory epithelium. Immunohistochemistry revealed the presence of olfactory marker protein (OMP), which is only found in mature olfactory sensory neurons. Although it seems that these neurons are scarce in bowhead whales compared to typical terrestrial mammals, our results suggest that bowhead whales have a functional sense of smell, which they may use to find prey.

Development of the squamate naso-palatal complex: detailed 3D analysis of the vomeronasal organ and nasal cavity in the brown anole Anolis sagrei (Squamata: Iguania)

Background

Despite the diverse morphology of the adult squamate naso-palatal complex - consisting of the nasal cavity, vomeronasal organ (VNO), choanal groove, lacrimal duct and superficial palate - little is known about the embryology of these structures. Moreover, there are no comprehensive studies concerning development of the nasal cavity and VNO in relation to the superficial palate. In this investigation, we used X-ray microtomography and histological sections to describe embryonic development of the naso-palatal complex of iguanian lizard, the brown anole (Anolis sagrei). The purpose of the study was to describe the mechanism of formation of adult morphology in this species, which combines the peculiar anole features with typical iguanian conditions. Considering the uncertain phylogenetic position of the Iguania within Squamata, embryological data and future comparative studies may shed new light on the evolution of this large squamate clade.

Results

Development of the naso-palatal complex was divided into three phases: early, middle and late. In the early developmental phase, the vomeronasal pit originates from medial outpocketing of the nasal pit, when the facial prominences are weakly developed. In the middle developmental phase, the following events can be noted: the formation of the frontonasal mass, separation of the vestibulum, appearance of the lacrimal duct, and formation of the choanal groove, which leads to separation of the VNO from the nasal cavity. In late development, the nasal cavity and the VNO attain their adult morphology. The lacrimal duct establishes an extensive connection with the choanal groove, which eventually becomes largely separated from the oral cavity.

Conclusions

Unlike in other tetrapods, the primordium of the lacrimal duct in the brown anole develops largely beyond the nasolacrimal groove. In contrast to previous studies on squamates, the maxillary prominence is found to participate in the initial fusion with the frontonasal mass. Moreover, formation of the choanal groove occurs due to the fusion of the vomerine cushion to the subconchal fold, rather than to the choanal fold. The loss or significant reduction of the lateral nasal concha is secondary. Some features of anole adult morphology, such as the closure of the choanal groove, may constitute adaptations to vomeronasal chemoreception.

Treatments for smell and taste disorders: A critical review

A key concern of both the patient and physician is whether treatment is available that will eliminate or quell a given chemosensory disturbance. In cases where obvious oral, nasal, or intracranial pathology is involved, rational straightforward approaches to treatment are often available. In cases where damage to the sensory pathways is secondary to chronic inflammatory disease, trauma, viral invasion, toxic exposure, or unknown causes, the direction for therapy is more challenging. Indeed, many chemosensory disorders, if present for any period of time, cannot be reversed, while others spontaneously remit without any therapeutic intervention. This review assesses the strengths and weaknesses of more than two dozen approaches to treatment that have been suggested for a wide range of taste and smell disorders.

Levels-of-Processing Effects on a Task of Olfactory Naming

The effects of odor processing were investigated at various analytical levels, from simple sensory analysis to deep or semantic analysis, on a subsequent task of odor naming. Students (106 women, 23.6 ± 5.5 yr. old; 65 men, 25.1 ± 7.1 yr. old) were tested. The experimental procedure included two successive sessions, a first session to characterize a set of 30 odors with criteria that used various depths of processing and a second session to name the odors as quickly as possible. Four processing conditions rated the odors using descriptors before naming the odor. The control condition did not rate the odors before naming. The processing conditions were based on lower-level olfactory judgments (superficial processing), higher-level olfactory-gustatory-somesthetic judgments (deep processing), and higher-level nonolfactory judgments (Deep-Control processing, with subjects rating odors with auditory and visual descriptors). One experimental condition successively grouped lower- and higher-level olfactory judgments (Superficial-Deep processing). A naming index which depended on response accuracy and the subjects' response time were calculated. Odor naming was modified for 18 out of 30 odorants as a function of the level of processing required. For 94.5% of significant variations, the scores for odor naming were higher following those tasks for which it was hypothesized that the necessary olfactory processing was carried out at a deeper level. Performance in the naming task was progressively improved as follows: no rating of odors, then superficial, deep-control, deep, and superficial-deep processings. These data show that the deepest olfactory encoding was later associated with progressively higher performance in naming.