Three-dimensional surface representation of the cilia-free nasal mucosa of man. A scanning-electron-microscopical study

Scanning electron microscopic findings in respiratory nasal mucosa following cigarette smoke exposure in rats

In the present study, the respiratory epithelium of the nasal mucosa of rats that had been exposed to cigarette smoke was examined by scanning electron microscope (SEM). Some significant morphological changes such as increased mucociliar activity, compound cilia, disorientation, short cilia and protrusive Goblet cells were observed.

Anatomical structure and surface epithelial distribution in the nasal cavity of the common cotton-eared marmoset (Callithrix jacchus)

To validate use of the common cotton-eared marmoset (Callithrix jacchus) in inhalation toxicity studies, its nasal morphology was examined. The nasal turbinates each consisted of one maxilloturbinate and one ethmoturbinate: these were more planar in structure than the comparable structures of rodents or dogs. The nasal cavity epithelia comprised squamous epithelium (SE), nasal transitional epithelium (NTE), respiratory epithelium (RE) and olfactory epithelium (OE), listed in order of occurrence from anterior to posterior positions. NTE was distributed as a narrow band lying between SE and RE. OE was limited to the dorsal part of the cavity, which was structurally similar to that of the macaque or man. Overall, this study revealed structural the similarity of the whole nasal cavity in the marmoset to that of macaques or humans. Prediction of nasal cavity changes in man based on extrapolation from experimentally induced changes in the common marmoset therefore seems likely to be feasible, making it a useful animal model for inhalation studies.

Epithelial damage of nasal mucosa in nasal allergy

Epithelial alterations arising from moderate nasal allergy to house dust were examined and compared to findings in epithelia from nonallergic controls. Biopsy specimens were taken during natural allergen exposure from two different sites: 1) the anterior tip of the inferior turbinate and 2) 2 cm behind it. The tissues were examined by both electron and light microscopy. In the allergic group, epithelial damage was found to be remarkable in the anterior nasal mucosae, where nonciliated cells were prevalent, but minor in the posterior nasal mucosae comprising ciliated and goblet cells. In the anterior nasal mucosae, conspicuous intercellular edema, epithelial shedding, and clusters of eosinophils in the epithelial layer were observed, whereas only a little epithelial shedding and edema in the basal area of the epithelium was noted in the ciliated areas. In controls, pathologic changes were not observed, although a little epithelial shedding was seen in the anterior turbinate. Although there are arguments for and against epithelial shedding in nasal allergy, this study confirms its presence even in patients with moderate allergy.

Effects of acute exposure to formaldehyde on surface morphology of nasal epithelia in rats

This study investigated the distribution of epithelial cells over the turbinates in the rat nasal cavity and their injury following exposure to formaldehyde. Rats were exposed to either purified air or 10 ppm formaldehyde for a period of 4 h. The noses removed from these rats were decalcified, sectioned midsagittally along the septum to expose the internal turbinates, and processed for examination by scanning electron microscopy. The distribution of the various cell types present was documented in the control rats. Observations obtained from the formaldehyde-exposed rats were compared to those in rats exposed to purified air. Changes were seen in the various regions of the turbinates in the form of ciliary destruction and cell separation (especially in the naso- and moxilloturbinates), cellular swelling (throughout the turbinates), mucus release by the goblet cells (in the nasoturbinate), and in some cases pores on the cell surface or between adjacent cells (evident in the middle meatus). The data from this study indicate that the degree of deleterious effects of formaldehyde on the nasal epithelia of rats is dependent upon cell type and location. Histological studies supported the scanning electron microscopic observations by demonstrating increased goblet cell volume, cell sloughing, and damaged cilia.

Nonolfactory surface epithelium of the nasal cavity of the bonnet monkey: a morphologic and morphometric study of the transitional and respiratory epithelium

The purpose of the present study was to characterize ultrastructurally the nonolfactory nasal epithelium of a nonhuman primate, the bonnet monkey. Nasal cavities from eight subadult bonnet monkeys were processed for light microscopy, and scanning and transmission electron microscopy. Nonolfactory epithelium covered the majority of the nasal cavity and consisted of squamous (SE), transitional (TE), and respiratory epithelium (RE). Stratified SE covered septal and lateral walls of the nasal vestibule, while ciliated pseudostratified RE covered most of the remaining nasal cavity. Stratified, nonciliated TE was present between SE and RE in the anterior nasal cavity. This epithelium was distinct from the other epithelial populations in abundance and types of cells present. TE was composed of lumenal nonciliated cuboidal cells, goblet cells, small mucous granule (SMG) cells, and basal cells, while RE contained ciliated cells, goblet cells, SMG cells, basal cells, and cells with intracytoplasmic lumina lined by cilia and microvilli. TE and RE contained similar numbers of total epithelial cells and basal cells per millimeter of basal lamina. TE was composed of more SMG cells but fewer goblet cells compared to RE. We conclude that nonolfactory nasal epithelium in the bonnet monkey is complex with distinct regional epithelial populations which must be recognized before pathologic changes within this tissue can be assessed adequately.

Transitional epithelial zone of the bovine nasal mucosa

To determine the extent and ultrastructure of epithelium lining the transitional nasal mucosa of the neonate, gnotobiotic calf tissues were prepared for scanning and transmission electron microscopy. Stratified cuboid epithelium of the rostral 40% of the nasal cavity contained few ciliated cells; the next caudal 10-15%, although ciliated, had extensive nonciliated areas. The predominant type of surface cell was nonciliated, had short microvilli, and contained a multilobate nucleus and numerous pinocytotic vesicles. In some areas the surface of these cells presented a cobblestone appearance. Basal cells contained numerous bundles of filaments, ribosomes, and basal vesicles. Caudally, nonciliated columnar cells included a cell type similar to the more rostral cuboid cell, as well as brush cells and immature secretory and ciliated cells. Goblet cells were infrequently observed. Intraepithelial nerve terminals were abundant. Other intraepithelial cells, often difficult to identify owing to varying characteristics, included lymphocytes. Based upon comparisons of this neonatal epithelium with mature epithelium, observed in earlier studies of other mammalian species, the transitional mucosa is believed normally to occupy an extensive area of the nasal cavity.

Endoscopic endonasal surgery--concepts in treatment of recurring rhinosinusitis. Part I. Anatomic and pathophysiologic considerations

Many years of endoscopic investigation and observation proved that most infections of the paranasal sinus are rhinogenic, spreading from the nose into the sinuses. The common focus of infection in cases of recurring sinusitis is the stenotic areas of the anterior ethmoid, with infection recurring in the larger sinuses. The anterior ethmoid, especially its infundibulum, is thus a key location for infection or cure, and maxillary as well as frontal sinuses are fully dependent on the pathophysiologic conditions there. Histologic examination demonstrates that massive changes of the nasal glands are the reason for permanent mucosal thickening. Retention cysts, highly viscous mucus, mucus extravasations, and metaplastic epithelial changes add to the vicious cycle of blockage of the ostium-meatus unit.

Surface topography and distribution of cell types in the rat nasal respiratory epithelium: scanning electron microscopic observations

Several cell types were identified in the rat nasal respiratory epithelium using scanning electron microscopy. In addition to the previously described ciliated, nonciliated, and goblet cells, the nasal brush cell was identified based on its surface characteristics and its location between nonciliated epithelial cells. Scanning electron microscopy clearly showed the differences in distribution of cell types in the nasal mucosa. The ciliated cells increase in number from the anterior to the posterior areas of the respiratory epithelium with a corresponding decrease in nonciliated cells. However, even at a single cross-sectional area of the nasal cavity, the various surfaces have different proportions of ciliated versus nonciliated cells, e.g., the medial surface of the nasal concha has more ciliated cells than other surfaces. Brush cells are distributed between nonciliated cells of the respiratory epithelium on most surfaces of the nasal cavity including the conchae and the lateral wall. Based on the available information, scanning electron microscopy will be useful in future studies to determine the effects that inhaled toxicants have on cells and on the location of lesions.

Nasal symptoms and histopathology in a group of spray-painters

Industrial workers more and more frequently seek medical advice for nasal and sinus symptoms that they attribute to occupational exposure. The present study comprised 10 paint-sprayers exposed to solvents (primarily toluene and isobutylacetate) and dust. The working environment was checked by an industrial hygienist and a careful clinical examination including biopsies from the nasal mucosa was carried out. The results revealed prominent nasal symptoms in 3 patients and 4 suffered from cough. The histological examination showed in no case a normal nasal mucosa. The histological grading showed a significantly higher score in the exposed group compared to a matched control group. However, no conclusive connection between the duration of exposure and the clinical symptoms and morphological changes was possible to make, which will necessitate an extended study to evaluate the exact importance of the duration of exposure. The study indicates the possibilities of an early presymptomatic detection of nasal mucosal disturbances and arises the question whether the existing TLVs are adequate in preventing damage to the nasal mucosa and adherent clinical symptoms.

Changes of nasal epithelial cells and mucus layer after challenge of allergen

It has been reported that the normal epithelium of the anterior nares is covered by a mucopolysaccharide layer with a depth of approximately 0.8μ1. In the present study, a patient with an allergy to the Japanese cedar was found to develop a very thin mucopolysaccharide layer (0.05μ in depth) when the mucosal tissue was taken off before provocation. Adhering pollen particles could have readily come in contact with the plasma membranes of the epithelial cells. The epithelium of the nonciliated cells exfoliated in a relatively short period of time after provocation. Ten minutes after provocation, a thick mucus layer covered the exfoliated epithelial mucosa. Pollen particles could no longer be brought into contact with mucosa due to the mucus layer. On the other hand, no difference from the normal condition was seen before provocation in the middle and posterior nares where ciliated cells were located. However, at ten minutes after provocation, a large number of goblet cells appeared in place of ciliated cells, and mucus production was very much activated. Many signs appeared at this stage which suggested the impairment of ciliary beating. Specifically, there was swelling and damage of plasma membranes of cilia, bending of cilia, existence of extra cytoplasm around the microtubules in the cilia, and intrusion of mucus fluid between cilia. In the regions where ciliated cells were replaced by goblet cells, the exfoliation of epithelium could be noted, but it is generally difficult to find that ciliated cells are exfoliated even when the ciliary beating is impaired. Taking into account the above-mentioned results, it can be assumed that pollen particles penetrate the submucosa not only through the posterior nares where ciliary beating is impaired, but also through the anterior nares where epithelial cells are exfoliated.

Abnormal "hair-like" filaments in chronic maxillary sinusitis . A scanning electron microscopic investigation

Scanning electron microscopic investigations were performed on the maxillary sinus mucosa of five healthy persons and seven patients with chronic maxillary sinusitis. The occurrence of previously undescribed hair-like filaments in one case of chronic maxillary sinusitis is presented. These abnormal filaments are much longer (about 50--60 micron) and thinner (about 0.08 micron) than normal kinocilia (about 0.2 micron thick and 5--7 micron long), thus exhibiting a hair-like appearance. As the microvilli (cytofila) in maxillary sinus mucosa have the same thickness (about 0.08 micron), these hair-like filaments could be regarded as abnormally long microvilli. The possible significance of these abnormal filaments is discussed.

[Scanning electron microscopy studies on epithel surface of the plica vocalis in male rats (author's transl)]

The epithelial surface of the Plica vocalis in adult male rat is studied by scanning electron microscopy. It's structure is compared with that of the plica and of the recessus ventricularis. The transition of the epithelium in the plica vocalis to the epithelium of the joining parts of the larynx is documented. Special attention is paid to the occurrence of microridges at the apical poles of epithelial cells in the larynx. Up to now microridge cells have been said to be characteristic for the plica vocalis.

[Scanning electron microscopy studies concerning the epiglottis epithelia of rats (author's transl)]

The epithelial surface of the epiglottis in adult male and female albino rats is studied by scanning electron microscopy. Prominent differences exist between the surface morphology as observed in the males and that observed in the females sacrificed in the estrus phase of the ovarial cycle. The differences are most pronounced in respect to the amount of secretory vesicles, microvilli- and microridge-cells and in respect to the observable number of desquamating cells. The existence and the importance of the microridge-cells are discussed. Special attention is also paid to the results indicating that at least some parts of the extrapulmonary airway epithelia act as possible target organs for sex hormones. Finally the importance of the observed differences is discussed for the correct interpretation of pathomorphological alterations in the extrapulmonary airway epithelia that have been observed under experimental conditions and during infections.

Microridge cells in the larynx of the male white rat. Investigations by reflection scanning electron microscopy

The laryngeal epithelium of male white rats is studied by reflection scanning electron microscopy (SEM). In addition to ciliated cells, microvilli cells, brush cells and goblet cells that are characteristic for normal respiratory epithelium the microridge or labyrinth cell can be seen in particular regions of the larynx. The apical surface of a typical labyrinth cell is characterized by a system of narrow standing microridges of about 0.05--0.15 micronm in diameter and interconnecting microridges with a diameter of about 0.01 micronm. The microridge system of a labyrinth cell originates from the fusion densely standing microvilli. Between microridge cells and microvilli cells all transition forms can be observed. The preferable localiziation of the microridge cell in the larynx and its possible function is discussed.