Showing papers on "Respiratory epithelium published in 1978"

The respiratory epithelium. I. Human bronchus.

Abstract: Six morphologic cell types comprise the human bronchial epithelium: basal cells that do not reach the bronchial lumen, neurosecretory cells (Kulchitsky's cells, K-cells, or small granule cells) that rarely reach the lumen, and indifferent cells, mucous cells [small mucous granule cells (SMGC) and mucous goblet cells], ciliated cells, and ciliated-mucous cells that do reach the lumen. Ciliated-mucous cells bearing fully developed cilia and containing mucous granules are seen only occasionally. Three of the cell types that reach the lumen are microvillus covered and do not bear cilia. The microvillus-covered nonciliated cells are: 1) neurosecretory cells, 2) indifferent cells, and 3) mucous cells. Neurosecretory cells contain characteristic dense core granules. Such cells rarely reach the lumen. Indifferent cells are rarely seen. They have a pale cytoplasm and show no evidence of either ciliary or mucous differentiation. Similar cells are observed showing early signs of either ciliary or mucous differentiation or even both types of differentiation in the same cell. Mucous cells comprise the vast majority of microvillus-covered cells. They present either as SMGC with a few small mucous granules or as goblet cells, filled with mucus. These columnar cells are characterized ultrastructurally by dense cytoplasm and a well-developed endoplasmic reticulum and Golgi apparatus. The microvilli are coated with a glycocalyx that binds colloidal iron more avidly than that of either cilia or microvilli of ciliated cells. Possible interrelationships between the different cell types in normal epithelium are discussed.

The effect of ascorbic acid on infection of chick-embryo ciliated tracheal organ cultures by coronavirus.

Abstract: Chick embryo tracheal organ cultures showed increased resistance to infection by a coronavirus after exposure to ascorbate, while chick respiratory epithelium and allantois-on-shell preparations showed no increase in resistance to infection by an influenza virus or a paramyxovirus.

The Respiratory Epithelium. II. Hamster Trachea, Bronchus, and Bronchioles

Abstract: The normal female hamster respiratory epithelium at five airway levels was characterized with the use of coordinated morphologic and histochemical techniques. Five morphologic cell types were recognized in the trachea, stem bronchi, and primary bronchl: basal cells and neurosecretory cells that were basally located and did not reach the lumen and mucous cells [mucous goblet cells and small mucous granule cells (SMGC)], indifferent cells showing mucous-ciliary differentiation, and ciliated cells that reached the lumen. Two epithelial cell types were observed in the bronchioles, ciliated cells and nonciliated Clara cells, both of which reached the lumen. Mucous cells presented as either SMGC with a few small periodic acid-Schiff-positive granules (diastase-resistant neutral mucosubstances) or as goblet cells, filled with the same material. Mucous cells were columnar, and the cytoplasm was electron-dense and contained a well-developed endoplasmic reticulum and Golgi complex. The microvilli of the mucous cells were coated more thickly with colloidal iron than either the cilia or microvilli of ciliated cells. Approximately one-half the cells in the trachea, bronchi, and bronchioles were ciliated. Ciliated cells containing intracellular ciliated cysts with normal cilia projecting into a closed space or ciliated cells bearing compound cilia were observed infrequently. Neurosecretory cells were rarely observed. These cells contained characteristic dense-core granules.

The Respiratory Epithelium. VI. Histogenesis of Lung Tumors Induced by Benzo[a]pyrene-Ferric Oxide in the Hamster

Abstract: Lung tumors were induced in female Syrian golden hamsters by intratracheal instillation of benzo[a]pyrene-Fe2O3. The tumors were characterized with the use of coordinated morphologic and histochemical techniques including electron microscopy. The lung carcinomas were classified according to their presumed cell of origin. Most were derived from mucous cells and/or basal cells, and they were classified as either epidermoid carcinomas or as combined epidermoid and adenocarcinomas. The tumors in the second group (57% of the total number of carcinomas) presented a wide spectrum of epidermoid and adeno components. The epidermoid component was characterized in well-differentiated tumors by the presence of intercellular bridges and/or keratinization. Well-developed desmosomes and numerous bundles of tonofilaments were observed ultrastructurally. In diagnosing adenocarcinoma, one no longer needs to depend on the presence of tubules or gross glandular structures as criteria for diagnosis. The presence of intracellular and/or extracellular alveoli, well-developed Golgi complex, and endoplasmic reticulum and/or evidence of mucous secretion provide more definitive criteria. A tumor composed of neurosecretory cells that morphologically resembled a bronchial carcinoid of man was observed. Nests of uniform, small, polygonal cells with round-to-oval nuclei were seen at the light microscopic level. Dense-core secretory granules 1,100-2,200 A were present in the cytoplasm of the tumor cells. Several fibrosarcomas were observed. The tumors showed a very cellular structure, composed of either densely packed ovoid or spindle-shaped cells. Ultrastructurally, the cells resembled fibroblasts. The results obtained in this study give strong support for a histogenetic classification, i.e., a classification based on the cell of origin.

The olfactory apparatus of the bandicoot (Isoodon macrourus): fine structure and presence of a septal olfactory organ

Abstract: The structure and extent of olfactory epithelium in the bandicoot (Isoodon macrourus) were examined by light and electron microscopy. Sensory epithelium covers most of the dorsal conchae, though non-sensory epithelium lines ventrally facing scrolls. The middle conchae are partly covered by olfactory epithelium, the proportion of olfactory to ciliated respiratory epithelium increasing caudally. Ventral conchae are lined by non-sensory ciliated epithelium. The nasal septum ends short of the floor of the nasal cavity in its caudal two thirds. It is covered dorsally by olfactory epithelium. The ventral margin has rounded lateral extensions which carry the isolated strips of olfactory epithelium which form the septal olfactory organ. The fine structure of the olfactory epithelium is the same in all areas. Cell types include olfactory receptors, supporting cells, two types of basal cell and rarer pale and brush cells. There is considerable morphological variation in olfactory cells, and evidence suggestive of continuing turnover in the receptor cell population.

Structure and function of mucus-secreting cells of cat and goose airway epithelium.

Abstract: In the cat and goose, studies have been undertaken to determine the ultrastructure of airway epithelia, the concentration and distribution of the secretory cells which produce respiratory tract mucus, and the histochemistry of mucins located within cells and on their luminal surfaces. By electron microscopy all the 11 cell types so far described can be found in the airways of the cat but not the goose. Both goblet cells and submucosal glands are abundant in the cat whereas the trachea of goose lacks the latter, having instead abundant goblet cells many of which form 'intraepithelial glands'. Histochemically, the goblet cells of the cat and goose are similar in that they contain mucins with a predominance of sulphate esters. A surface mucosubstance can be demonstrated which, histochemically, is similar to that described in dog and man. Interestingly, this surface layer may be sloughed in response to an inhaled irritant such as ammonia and thereby contribute to the respiratory tract mucus recovered experimentally. Incorporation into macromolecules of radioactively labelled mucin precursors is assessed by autoradiography of tissue sections, and preliminary results of experiments designed to test the response of mucus-secreting cells to airway irritation and the parasympathomimetic drug, pilocarpine, are also presented.

Morphological and functional differentiation of the surface epithelium of the bursa Fabricii in chicken.

Abstract: Morphological and functional differentiation of the mucosal surface epithelium of the bursa Fabricii was studied in White Leghorn chicken fetuses and newly hatched chickens. First signs of differentiation towards two types of epithelial cells appeared on the thirteenth day of incubation: The apical cells of the epithelial buds projected towards the lumen, and an increase in the number of Golgi regions was observed in the epithelial cells between the buds. On day 15 the follicle-associated epithelium contained small apically situated vacuoles, and large mucin granules appeared in the interfollicular surface epithelium. Towards the day of hatching both epithelial cell types were arranged to a monolayered or pseudostratified cylindrical epithelium. The follicle-associated epithelium had invaginations and small vacuoles in the apical cytoplasm, whereas the interfollicular surface epithelium had numerous microvilli on its apical surface and large mucin granules in the apical cytoplasm. In functional studies, endocytosis of colloidal carbon was demonstrated in four out of ten 19-day fetuses and in all chickens studied immediately after hatching.

Histological and ultrastructural specialization of the digestive tract of the intestinal air breather hoplosternum thoracatum (teleost).

Abstract: The digestive tract of Hoplosternum thoracatum consists of an esophagus, gastric area, anterior digestive intestine with elaborate folds, digestive intestine with decreasing folds and thin, smooth-surfaced respiratory intestine. The upper tract has a mucoid columnar lining which is gently folded, whereas the gastric area has numerous pits opening into the tubular secretory glands. Striated muscle comprises the anterior muscularis but is replaced by inner circular and outer longitudinal smooth muscle layers in the gastric region. The digestive intestinal mucosa is elaborately folded, consisting of columnar cells with prominent brush borders. Mucosa, submucosa, circular and longitudinal muscularis and serosa layers are present throughout the tract. Goblet cells occur in both the digestive and respiratory intestine. Major changes that appear in the respiratory intestine are a drastic reduction in mucosa epithelial thickness and the penetration of an elaborate capillary bed into the epithelium. The other basic layers are not significantly reduced in thickness. The air-blood barrier consists of the thin epithelium, basement lamina and very thin capillary endothelium. Regional cellular composition and ultrastructural features are correlated with respective digestive and respiratory functions.

Respiratory tract epithelium in primary culture: concurrent growth and differentiation during establishment.

Abstract: Studies of cellular function in the respiratory tract lining have traditionally been limited by the small tissue mass and functional diversity of the epithelium. Recent improvements in culture conditions have permitted long-term maintenance of epithelial cells derived from the upper respiratory tract of rats. The present study determined the extent to which proliferation and differentiation took place in such epithelial cell cultures. The labelling index obtained after 3H-dThd administration was approximately 100-fold higher than that of the quiescent epithelium in vivo; therefore, a large proportion of the cells were probably in the cycling population. Ultrastructural studies showed that features unique to the specialized mucous secretory cells and ciliated cells were lost rapidly with entry of these cells into the in vitro environment. With long-term maintenance, the cultures were reorganized into a stratified epithelium containing large, squamous, apical cells and small basal cells. The ultrastructural appearance of basal cells in vitro was nearly identical to that of basal cells in vivo. Squamous cells were frequently joined by tight junctions. Because hemicysts originated by detachment of squamous cells from the basal layers but not from adjacent squamous cells, they were considered to indicate stratification in the cultures. The proliferative and differentiative status of the mucociliary epithelium was altered by in vitro conditions, and came to resemble that of early squamous metaplasia in the respiratory tract epithelium.

Morphology of the epithelium in the alimentary tract of the larval lamprey, Petromyzon marinus L

Abstract: The alimentary tract of the ammocoete of the lamprey, Petromyzon marinus L., is divisible into three morphologically distinct regions: the oesophagus, the anterior intestine, and the posterior intestine. The epithelium of the oesophagus possesses mucous, ciliated, and columnar cells and appears to be specialized for movement of food particles. The epithelium of the anterior intestine possesses secretory cells with numerous zymogen granules, ciliated cells, and columnar-absorptive cells. Although some absorption occurs in the anterior intestine, the main function of this region seems to be the release of digestive enzymes and the continued movement of food particles. The epithelium of the posterior intestine is entirely comprised of columnar absorptive cells, namely tall (light and dark) columnar and low columnar, and the primary function of this region is one of absorption. The epithelium of the hindgut resembles that of the archinephric duct (Youson and McMillan, '71). The morphology of the alimentary tract of ammocoetes suggests that some differentiation and renewal of cell types may occur in the epithelium of the three regions. Comparison of the alimentary tract of larval lamprey with that of other vertebrates indicates that the gut of the ammocoete represents a less specialized level of vertebrate development.

Bronchial mucus hypersecretion induced by elastase in hamsters: ultrastructural appearances.

Abstract: Male golden hamsters were exposed to a solution of purified pancreatic elastase by intratracheal injection. They developed panlobular (panacinar) emphysema and, in addition, were found to show severe goblet cell metaplasia in the major bronchi. The metaplastic change in the respiratory epithelium was associated with persistence of a fenestrated sheet of mucus, widely present throughout the bronchial tree, which was greater in amount than that in either unexposed or saline exposed controls. Transmission electron micrography showed a striking increase in size of individual goblet cells, due to increased numbers of secretory droplets which were also much larger and paler than in control bronchi. Ciliated cells appeared smaller than normal due to compression by the swollen goblet cells. The presence of prominent dilatation of the endoplasmic reticulum and the increased frequency of secretory droplet release from the luminal surface stronly suggest that the goblet cell changes were due to increased formation and secretion of mucus into the damaged bronchi. These experiments show that a single exposure to elastase produces both severe panlobular emphysema and goblet cell metaplasia. The changes resemble several of the anatomic features of chronic obstructive lung disease in man for which this injury may be a suitable model.

Ciliated respiratory epithelial monolayers: new model for Mycoplasma pneumoniae infection.

Abstract: Hamster respiratory epithelial cells were cultured in a monolayer format, and 20% of the cells were ciliated. Mycoplasma pneumoniae attached to the epithelial cells in a neuraminidase-specific fashion and induced ciliostasis and cytonecrosis.

Long-term organ culture of human uterine endocervix.

Abstract: Explants of human endocervix have been maintained in organ culture for 24 weeks. The epithelium was viable for the entire duration of culture, as demonstrated by ultrastructural morphology and mitotic activity. The epithelium of the explants retained a near normal morphology for 2 to 4 weeks. The only changes observed were decreased mucus secretion in columnar cells, focal epidermoid metaplasia, and an increase in autophagic vacuoles. Subsequently, a slowly progressive transformation of the columnar epithelium into a metaplastic epithelium was observed, with loss of mucus-secreting columnar cells and ciliated cells and the appearance of cuboidal and flattened epidermoid cells, forming often two to three layers. Metaplasia began at the top of the papillae and ridges and extended progressively downwards into the clefts. Nevertheless, in a few areas deep in the clefts, columnar cells retained evidence of mucus secretion during the entire duration of culture. Epidermoid metaplasia appeared to develop in the explants by transformation of columnar mucous cells into cuboidal and flattened cells with epidermoid characteristics. This hypothesis is supported by ultrastructural observations that showed mucus secretion and early keratinization in the metaplastic cells. Mitotic figures were observed with transmission electron microscopy for up to 24 weeks, and all dividing cells contained mucous granules.

The Glycoproteins of Secretory Cells in Airway Epithelium

Abstract: Quantitative histochemical methods demonstrate a variety of glycoproteins within mucus-secreting cells of airway epithelium. A single cell may synthesize one or a combination of four major types--(i) neutral glycoprotein, (ii) and (iii) sialylated either sensitive or resistant to sialidase and (iv) sulphated. In human airway disease, or in experimental response to inhalation of an irritant, there is mucus cell hyperplasia and change in the proportion of cells synthesizing the various types. Experimental studies show how speedily these changes occur. In rats exposed to tobacco smoke changes are found within 20 h of the first exposure. Only in the extrapulmonary epithelium is there discharge of the secretions, with an apparent fall in cell number. Modification of glycoprotein may occur with an unchanged or increased cell number, suggesting that it occurs in existing and newly appearing secretory cells. Modification of the contents of the granule occurs toward the cell apex. Modification of glycoprotein synthesis towards the normal is also the most sensitive and earliest sign of recovery.

The effect of isoprenaline and pilocarpine on mitotic index and goblet cell number in rat respiratory epithelium.

Abstract: The effect of both isoprenaline (IPN) and pilocarpine (PCP) on mitotic activity and goblet cell number has been studied at 5 levels of the bronchial tree in male and female animals. While both drugs increased mitotic index and goblet cell number at most of the airway levels studied, differences in their effect were detected. After both drugs, nuclei in division were more often superficial within the epithelium than basal but IPN caused a greater increase in mitotic index than PCP. IPN increased goblet cell number at all levels, PCP only in the trachea and larger intrapulmonary airways. The types of goblet cell increased by IPN were particularly those containing acid glycoprotein, whereas PCP increased all types of goblet cell, that is, both those containing neutral and acid glycoprotein. After the drugs, the concentration of cells per unit length of airway epithelium was higher than normal. This is the first study demonstrating the effect of these two drugs on both goblet cell number and cell division. While the two drugs differ in their pharmacological action, the result of their stimulation of airway epithelium is similar. The way in which each effect is produced is discussed.

Regulation of Na+ and Cl- transport and mucous gland secretion in airway epithelium.

Abstract: Ussing's short-circuit technique was applied to canine airway epithelium in vitrol and a net flux of Cl- towards the airway lumen was demonstrated, with a smaller net flux of Na+ in the opposite direction. Furosemide decreased and acetylcholine, terbutaline, and histamine increased net ion transport towards the airway lumen. Associated changes in water content in the airway lumen could affect mucociliary clearance, and therefore inhibition of ion transport may play a role in disease states. To study secretions from submucosal glands in vivo, two techniques were used to identify the duct openings in the exposed canine tracheal epithelium. (a) The exposed mucosal surface was coated with powdered tantalum; accumulated secretions produced elevations under which the duct openings were located. (b) A vital dye (0.1% Neutral red) was placed on the exposed mucosal surface; the dye stained the duct openings. With these techniques, the innervation of the submucosal glands and the autonomic regulation of their secretions were studied. Micropuncture techniques were used to sample the secretions from the glands and ducts.

The development of the epithelium and its innervation in the avian extra-pulmonary respiratory tract.

Abstract: The development of the epithelium and its innervation was investigated with the electron microscope in the larynx and trachea of embryo domestic fowls between the 10th and 21st days of incubation. From days 10 to 16 the airways were lined by undifferentiated cells which on day 15 or 16 became arranged in two distinct layers. Differentiation of the epithelial cells commenced on day 17, so that at hatching on day 21 fully differentiated ciliated cells, goblet cells, non-ciliated columnar cells, granular cells and basal cells were arranged into a simple or pseudostratified columnar epithelium. Comparisons are made with the differentiation of the respiratory epithelium in other vertebrates. Intra-epithelial axons were first seen on day 15 and increased rapidly in number. The varicose axon profiles contained both granular and agranular vesicles. The axons lay close to most types of epithelial cell, and some approached near to the surface of the epithelium. A synaptic complex, possibly efferent, involving a granular epithelial cell is described.

Transport in Eye Epithelia: Ciliary Epithelium and Retina Pigment Epithelium

Abstract: The ciliary epithelium and the retina pigment epithelium constitute the main sites of the blood-ocular barrier and their functions are the restriction of permeability and the secretion of electrolytes and nonelectrolytes, which are of importance for the maintenance of the intraocular pressure in the case of the ciliary epithelium, and the nutrition of the outer neural retina in the case of the retina pigment epithelium. The aqueous humor is a transparent fluid occupying the anterior and posterior chambers of the anterior segment of the eye. Its secretion depends on a mechanism of transport of electrolytes and water, and also on ultrafiltration. Ultrafiltration depends on the differences between the pressure in the arterioles of the ciliary body and the intraocular pressure. The fluid escapes from the anterior chamber through the canal of Schlemm into the venous system. A restriction to this outflow exists, which maintains the intraocular pressure at the constant physiological level. As the eye is an elastic sphere with a gel (the vitreous body) occupying the posterior portion and a fluid being secreted and circulating slowly in the anterior portion, the control of the pressure is maintained by this secretion-outflow system of the aqueous humor.

Pathologic changes induced in respiratory tract mucosa by polycyclic hydrocarbons of differing carcinogenic activity.

Abstract: Seven aromatic polycyclic hydrocarbons (PCHs) were investigated for their toxic effects on respiratory mucosa: benzo(e)pyrene (BeP), pyrene, anthracene, benz(a)anthracene(BaA), dibenz(a,c)anthracene(DBacA), benzo (a)pyrene (BaP), and dimethylbenz(a)anthracene (DMBA). The compounds were chosen because they comprise a spectrum of PCHs ranging from noncarcinogens, to initiators, to weak and strong carcinogens. All of them except DMBA are environmentally relevant chemicals. The chemicals were tested over an 8-week period. Heterotopic tracheal transplants were continously exposed and the histopathologic effects induced by the various PCHs were periodically assessed semiquantitatively. All PCHs exhibited varying degrees of toxicity for respiratory epithelium and submucosa. BeP clearly showed the least toxicity followed by pyrene and anthracene. BaA and DBacA caused marked epithelial and submucosal changes. In addition to epithelial hyperplasia, undifferentiated epithelium and squamous metaplasia developed. Marked mononuclear infiltration occurred in the subepithelial connective tissue. With BaP the epithelial and submucosal changes were similar but were much stronger. DMBA was the most toxic substance, causing epithelial necrosis followed by generalized keratinizing squamous metaplasia; the subepithelial changes consisted of an early acellular exudate and, later (at 8 weeks), marked condensation and hyalinization of the lamina propria. The toxic response pattern of the tracheal mucosa to carcinogenic agents was characterized by the chronicity of epithelial and connective tissue damage, as opposed to the short-lived hyperplastic and inflammatory response elicited by the noncarcinogens and weak initiators.

The respiratory epithelium in the lungs of the slow-worm, Anguis fragilis.

Abstract: The epithelium covering the respiratory portion in the lung of the slow-worm (Anguis fragilis) has been studied by electron microscopy. The epithelium is composed of two different types of pneumonocytes. The type I pneumonocytes are roughly squamous and their cytoplasmic sheets spread over relatively large areas of the septal walls. These cytoplasmic sheets are attenuated in regions where they overlie septal capillaries; they usually have extensive areas of contact with adjacent cells. The type II pneumonocytes are also squamous but are more compact and possess more organelles. Their osmiophilic inclusion bodies are especially conspicuous. Most of their microvilli are concentrated on the surfaces of cytoplasmic “hillocks”. Deposits of membranous material are present in the air sacs. The morphological evidence suggests that the type II cells of Anguis secrete surface-active material.

Branching microvilli in the nasal respiratory epithelium.

Abstract: • In an ultrastructural study of the respiratory epithelial covering of 14 human nasal mucous polyps, some of the microvilli overlying the ciliated cells were shown to exhibit a complex form of branching with a resultant increase in surface area. This apparently original observation is of uncertain significance but is not of definite pathological significance. (Arch Otolaryngol104:260-262, 1978)

Respiratory epithelium within a mandibular dentigerous cyst.

Abstract: A case report of a dentigerous cyst of the mandible with respiratory epithelium has been described. A review of the literature shows this to be only the fourth case reported. The three most current theories to explain this phenomenon have been presented.

Parainfluenza-3 Virus Neuraminidase and Antineuraminidase in Infection and Protection of the Bovine Respiratory Tract

Abstract: The respiratory tract is covered by a mucus layer. It consists of a superficial gel phase and a liquid phase beneath. The gel phase contains inhibitors to parainfluenza-3 virus (PIV-3). The majority of these are sensitive to neuraminidase. The PIV-3 particle has to pass through (penetrate) the mucus layer to infect the respiratory epithelium. It has been suggested that PIV-3 penetrates the gel phase by aid of its neuraminidase which releases the virion from the inhibitors.