Showing papers on "Respiratory epithelium published in 1980"

Role of pili in adherence of Pseudomonas aeruginosa to mammalian buccal epithelial cells.

Abstract: Adherence of Pseudomonas aeruginosa organisms to the upper respiratory epithelium of seriously ill patients in vitro is correlated with subsequent colonization of the respiratory tract by this opportunistic pathogen. The role of pili in the attachment to epithelial cells of P. aeruginosa was studied in an in vitro system employing human buccal epithelial cells and P. aeruginosa pretreated by various means. Pretreatment of the bacteria with proteases, heat, or Formalin caused a significant decrease in adherence. A decrease when compared with controls was also noted in the adherence of P. aeruginosa organisms to buccal epithelial cells preincubated with purified pili prepared from the strain used for adherence testing; however, pili prepared from a heterologous strain failed to block adherence. Similar results were obtained in serological studies when antisera to purified pili prepared from the strain used for adherence testing decreased adherence, whereas heterologous antiserum to pili did not decrease adherence. From these results it appears that pili mediate the adherence of P. aeruginosa organisms to human buccal epithelial cells.

Acute respiratory bronchiolitis: an ultrastructural and autoradiographic study of epithelial cell injury and renewal in Rhesus monkeys exposed to ozone

Abstract: The pathogenesis of acute respiratory bronchiolitis was examined in rhesus monkeys exposed to 0.8 ppm ozone fpr 4--50 hours. Epithelial injury and renewal was qualitatively and quantitatively characterized by correlated techniques of scanning and transmission electron microscopy as well as by light-microscopic autoradiography following labeling with tritiated thymidine. Extensive degeneration and necrosis of Type 1 epithelial cells occurred on the respiratory bronchiolar wall during the initial 4--12 hours of exposure. Increased numbers of labeled epithelial cells were present in this region after 18 hours of exposure, and the highest labeling index (18% was measured after 50 hours of exposure. Most (67--80%) of the labeled cells and all the mitotic epithelial cells (22) observed ultrastructurally were cuboidal bronchiolar epithelial cells. Of the labeled epithelial cells, 20--33% were Type 2 epithelial cells. After 50 hours of exposure the respiratory bronchiolar epithelium was hyperplastic. The predominant inflammatory cell in respiratory bronchiolar exudate was the alveolar macrophage. Monkeys that were exposed for 50 hours and allowed to recover in unozonized air for 7 days had incomplete resolution of respiratory bronchiolar epithelial hyperplasia. The results indicate that Type 1 epithelial cells lining respiratory bronchioles are the cell type most sensitive to injury and that both cuboidal bronchiolar epithelial cells and Type 2 epithelial cells function as stem cells in epithelial renewal.

The distribution and structure of cells in the tracheal epithelium of the mouse.

Abstract: The tracheal epithelium of the mouse is a single layer of columnar cells resting on a basement membrane. Many of the cell types resemble those of other species. However, goblet cells are rare and ciliated cells occur only in scattered patches. Submucosal glands are absent from all but the highest reaches of the airway. The major proportion of the epithelial cells are non-ciliated. These usually project into the lumen of the trachea. Large amounts of smooth endoplasmic reticulum and many secretory vesicles occur within the cytoplasm. Secretory activity of these cells may be either apocrine or merocrine and these cells may transform into other cell types. It is suggested that these non-ciliated cells are Clara cells and that the mouse tracheal epithelium may make a useful model for the study of this type of cell.

beta-Adrenergic stimulation of respiratory ciliary activity.

Abstract: We investigated the effect of isoproterenol on ciliary activity using a mucus-free preparation of cultured ciliated cells of the rabbit trachea. The frequency of ciliary beating was monitored by dynamic laser-scattering spectroscopy. The results demonstrated that isoproterenol directly stimulates the activity of ciliated cells of the respiratory epithelium and that this effect is beta-adrenergic specific inasmuch as the observed stimulation can be blocked by propranolol.

A study of the histology and morphology of the digestive tract of the common eel (Anguilla anguilla)

Abstract: The anatomy and morphology of the digestive tract of the eel was examined using light and scanning electron microscopy. The oeosphagus showed complex longitudinal folding; stratified epithelium, columnar epithelium and goblet cells striated muscle fibres formed the thick muscular coat. The pneumatic duct entered the oesophagus anterior to the oesophagastric junction. The Y shaped stomach showed large well developed folds which decreased in size and number towards the pyloric sphincter. Columnar epithelium and gastric gland cells were present, the latter being absent from the pyloric region. The intestine had a heavily thickened anterior region, signs of convulation were noted prior to the ileorectal valve. Intestinal folding showed a complex reticulate pattern with columnar epithelium and goblet cells present. The mucopolysaccharides were studied in the goblet and columnar cells throughout the regions of the gut. Lymphocytes and eosinophilic type cells were found in the connective tissue of the mucosa throughout the gut. The pancreas was a compact organ with few Islets of Langerhans, beta cells were peripherally situated and alpha cells centrally. The unilobular liver acted as a storage organ for oil and glycogen.

Ultrastructure of Regenerating Junctional Epithelium in the Monkey

Abstract: It has been established that after gingivectomy the junctional epithelium is reformed from the oral epithelium but there is little information on the regenerative potential of residual junctional epithelium. In this study reformation of the epithelial attachment in the monkey was followed ultrastructurally after surgical removal of all of, or of part of, the original junctional epithelium by internal or external bevel techniques respectively. In both circumstances a new epithelial attachment developed from the adjacent gingival oral epithelium and residual junctional epithelium appeared to persist as small nests of cells adjacent to the cemento-enamel junction. Epithelialization of the gingival wound was rapid, taking place in as little as 5 days after the partial removal of the junctional epithelium by the external bevel technique and by 10 days in wounds in which the junctional epithelium had been completely excised. This difference in the rate of epithelialization seemed to be primarily related to the quantity of coagulum and cell debris present, the greater amount remaining after the internal bevel technique tending to retard epithelial migration and reattachment.

Selective isolation and culture of a proliferating epithelial cell population from the hamster trachea.

Abstract: A reliable cell isolation technique was developed to allow the cultivation of cells from the hamster respiratory tract. Repeated thermolysin treatments and gradient centrifugation yielded a cell culture completely free from contamination by fibroblasts. Viable cells could be isolated from as little tissue as a single hamster trachea, but in vitro proliferation occurred only if the hamster was less than 4 months of age. The cultured cells could be repeatedly passaged and subcultured for weeks by employing normal tissue culture techniques. Morphologically, the monolayers appeared to be a homogeneous population of epithelial cells, and successful cloning of freshly isolated single cells resulted in apparently identical cultures. The epithelial origin of these cells was also suggested by continued growth in minimum essential medium withd-valine substituted forl-valine. The relative ease with which this cell type can be isolated, cultured, and manipulated in vitro should encourage its application as a model of the respiratory epithelium.

Heterogeneity of tight junction morphology in extrapulmonary and intrapulmonary airways of the rat

Abstract: In the present study morphology of tight junctions was related to the various cell types lining extrapulmonary and intrapulmonary airways of the rat. Freeze fracture replicas were prepared from extrapulmonary airway epithelium derived from the cartilagenous and membranous sides of upper, middle, and lower thirds of the trachea. Intrapulmonary airway epithelium was obtained from airways less than 1 mm in diameter. Tight junction fibrils on the P fracture face were organized into three types of patterns. Type 1: parallel sparsely interconnected lumenal fibrils with large ablumenal fibril loops. Type 2: richly interconnected lumenal fibrils with large ablumenal fibril loops. Type 3: narrow network of interconnected fibrils. On the E fracture face complementary grooves were organized in a similar pattern. Ciliated cells on both sides and all levels of the trachea were associated with type 1 junctions. In intrapulmonary airways, however, the junctional pattern of ciliated cells changed to type 2. Brush cells at all levels of the airways were bounded by type 2 and occasionally by type 1 junctions. Secretory cell junctions displayed the following patterns: Mucous cells were bounded solely by type 3, serous cells by either types 2 or 3, and Clara cells predominantly by type 2. Cells tentatively identified as intermediate cells displayed all three junctional patterns. The number of parallel fibrils comprising tight junctions was higher in extrapulmonary as compared to intrapulmonary airways. No difference was seen in the various locations sampled in the trachea. Gap junctions were observed between secretory cells of extrapulmonary but not intrapulmonary airways. These observations are discussed in relation to current physiologic data.

The ultrastructure of rat laryngeal epithelia.

Abstract: The histology and ultrastructure of the rat laryngeal epithelia are described Five epithelial types were identified Stratified squamous epithelium was found over most of the epiglottis, arytenoid projections and lateral ventricles The vocal folds were covered by a low squamoid type of epithelium Respiratory epithelium, similar to that found elsewhere in the respiratory tract, occupied all the mucosa caudal to the vocal folds, small areas at the base of the epiglottis and along the inner aspects of the arytenoid projections Two forms of relatively unusual pseudostratified cuboidal epithelium were present in the ventrolateral aspect at the level of the arytenoid projections and within the ventral pouch Non-myelinated, intro-epithelial nerve fibres were found throughout the larynx, and were abundant in areas at the base of the epiblottis covered by respiratory epithelium and to a lesser extent in the cuboidal epithelium of the ventral pouch Globule leucocytes were frequently found within respiratory epithelium, less frequently in cuboidal epithelium and only rarely in squamous areas

Respiratory disease in rats associated with a filamentous bacterium : a preliminary report

Abstract: A naturally occurring, chronic disease of the respiratory tract was investigated from the time of its onset to completion of life-time studies in a colony of rats. The disease was characterized by peribronchial lymphoid cuffing, suppurative bronchitis, bronchiectasis and bronchial abscesses. Its onset in the colony occurred a few months after an epizootic of Sendai virus infection. Limited retrospective serological testing indicated that Mycoplasma pulmonis may have been present in the colony at that time and continued to persist throughout life in some rats in the colony. Although of uncertain significance, light and electron microscopy consistently demonstrated many filamentous bacteria between the cilia on respiratory epithelium and free in bronchial exudate in these cases. Attempts to culture this organism on artificial media were unsuccessful.

Lung mucus production and mucociliary clearance: methods of assessment.

Abstract: The primary defence mechanism of the tracheobronchial tree against all types of inhaled particles is the mucociliary escalator. This is composed of ciliated epithelium extending from the larynx to the terminal bronchioles (16th division of Weibel, 1963), on which lies a layer of mucus, the mucus blanket. As well as ciliated columnar cells, the tracheobronchial epithelium contains goblet cells which secrete mucus, the ratio between the two being 5 to 1 with a relative decrease in the number of goblet cells from the trachea to the lung periphery. Each ciliated cell has on its surface about 200 cilia of average length 6 µm and diameter 0.2 µm. Epithelial serous and Clara cells are also secretory cells, the latter being more numerous in the bronchioles and on occasion capable of transition to goblet cells on irritation. The submucosal glands are simple tubuloalveolar structures present in the cartilage containing trachea and bronchial tree but not in bronchioles. Each gland contains both mucus and serous cells as well as myoepithelial cells which may serve to extrude secretions.

Cell proliferation in follicle-associated epithelium of mouse Peyer's patch.

Abstract: Follicle-associated epithelium (FAE) from the mouse Peyer's patch consists of a dome part containing goblet as well as columnar epithelial cells and a crypt part, containing Paneth as well as goblet and undifferentiated epithelial cells. The proportions of columnar epithelial, goblet and Paneth cells in the FAE are similar to those found in normal crypt/villus complexes. Mitosis is confined to the crypts of the FAE. The cell-renewal time for FAE columnar epithelial cells, estimated from experiments using tritiated thymidine, is approximately 60 hours. Large numbers of lymphoid cells are also present in the FAE, particularly in regions distal to the crypts. The similarity between follicle-associated and villus epithelial structure is discussed, together with its possible relevance to “M” cell formation within the FAE.

Scanning electron microscopic demonstration of goblet cell discharge and mucous layer on nasal ciliated respiratory epithelium.

Abstract: Respiratory cilia is covered by a layer of mucus. The manner in which the mucus makes its way to the cilia tips and distributes itself on the tips is not known. Scanning electron microscopic examination of nasal mucosa demonstrated cone-like goblet cell discharge as well as a thin layer of mucus enmeshed in the cilia tips. Further demonstration of mucus may demonstrate the differences in these two components.

Changes in the Differentiation Pattern of Oral Mucosal Epithelium Following Heterotopic Connective Tissue Transplantation in Man

Abstract: Anterior palatal connective tissue was transplanted into wound beds created within the alveolar mucosa of the lower anterior vestibulum in seven adults females. Six months postoperatively, the epithelial lining of the inverted transplants was biopsied and compared histologically, histometrically, and stereologically to the neighboring mucosal epithelium. The data suggest that (1) connective tissue of the lamina propria is primarily responsible for the structural specificity of the overlying epithelium, (2) inductive stimuli are not confined to superficial layers but also originate from deep portions of the lamina propria, (3) these stimuli influence both the epithelial differentiation and the type of epithelium-connective tissue interface, and (4) the epithelial response to the inductive stimuli in man may depend on the individual type of epithelial differentiation pattern originally prevailing at the recipient site. The transplant-lining epithelium assumed features resembling that of the hard palate in subjects with an alveolar mucosal epithelium with cheek-type characteristics. In subjects with an alveolar epithelium displaying a mixed differentiation pattern, the transplant-lining epithelium continued to generate a mixed pattern or else shifted to more palate-like characteristics.

Morphology and Histochemistry of Non-Tumorous Gallbladder Epithelium. A Series of 103 Cases

Abstract: One hundred and three gallbladders were excised from 81 female and 22 male patients. Different non-tumorous morphologic and histochemical changes and their frequency were studied in these gallbladders and in their various components. Histochemical methods were used to visualize sulphated, non-sulphated acid, and neutral mucins. Sulphated mucin predominated in normal columnar epithelium and in the glands of the neck region, whereas non-sulphated acid mucin and neutral mucin predominated in goblet cell areas, in superficial gastric-type epithelial areas and in antral-type glands. Goblet cells were present in 67 specimens, enterochromaffin cells in 42, superficial gastric-type epithelium in 16, antral-type glands in 40, antral-type mucosa in 8 and intestinal-type mucosa in one specimen. Goblet cells, enterochromaffin cells, and gastric surface epithelium columns appeared initially in the surface portions of the folds. No relationship was established between the degree of metaplasia, the age of the patient, the duration of symptons, and the severity of illness.

Distribution and ultrastructural characteristics of Feyrter cells in the rat and hamster airway epithelium.

Abstract: Feyrter cells were found both singly and in groups at all levels of the respiratory tract studied in both rats and Syrian golden hamsters. Particularly large and prominent groups of Feyrter cells were present at bronchiolar bifurcations and bronchiolar-alveolar junctions. Single Feyrter cells were also found throughout the respiratory tract, but their distribution appeared entirely random. In all cases examined the groups of Feyrter cells were overlaid by intermediate and serous secretory epithelial cells. Occasionally small areas of the Feyrter cells were exposed to the airway lumen. Small canaliculi-like intercellular spaces were present between adjacent Feyrter cells. Single unmyelinated axons which contained neurotubules, mitochondria, and vesicles were occasionally seen in close association with Feyrter cells.

Scanning and transmission electron microscopic study of the lung of the newt, Triturus alpestris Laur.

Abstract: The lungs of Triturus alpestris Laur. were investigated with the scanning and transmission electron microscopes. Dimensions of the cell bodies of pneumocytes and ciliated cells, as well as the thickness of the air-blood barrier, were determined. The lungs of the newt form two simple sacs without septa. A ciliated epithelium containing goblet cells lines the pulmonary vein and partially the pulmonary artery. The remainder of the lung surface is covered internally by respiratory epithelium consisting of one type of cell and only occasionally showing the presence of single ciliated cells. All cells, ciliated, goblet and pneumocytes, contain in their cytoplasm lamellar bodies. Multivesicular bodies and numerous vesicles of variable electron density also occur in the cytoplasm of pneumocytes. Atypical mitochondria can be found in all cell types of the lung. Fixation with addition of tannic acid reveals the surface lining film. Tubular myelin figures were not observed.

Chemical modulation of airway epithelial permeability.

Abstract: The mucosal surface of the conducting airways has specialized structures for respiratory defense. Glands secret mucus that may act as a barrier to particle penetration and participate in particle clearance. Intraepithelial irritant receptors aid in particle clearance through airway constriction and cough. The epithelium acts as a barrier to the penetration of inhaled material into the airway wall. Morphologic studies have identified the tight junctions adjoining respiratory epithelial cells as the principal barrier to passive solute translocation across the airway. New approaches have been used to study airway epithelial function. Use of excised canine trachea mounted in Ussing chambers has permitted quantitative estimates of probe molecule permeation, the correlation of permeability with bioelectric properties, and estimation of equivalent pore radii. Probe molecule diffusion across canine trachea [mean transmucosal electric potential difference (PD) = 33 mV, lumen negative] is directly related to conductance (2.9 mS/cm2) and is compatible with an equivalent pore radius of 7.5 nm. Direct measurement of tracheal PD in vivo (-29 mV) facilitates study of the genesis of the biopotential in intact animals. Measurement of the movement of HRP by radioimmunoassay has allowed correlation of the rate of probe flow across airway walls in vivo with ultrastructure. These approaches lend themselves to the study of pharmacologic and toxicologic effects on epithelial function. Antigen challenge, diethyl ether, and unfractionated cigarette smoke have been shown to increase epithelial permeability to HRP accompanied by ultrastructural evidence of tight junctional damage. Application of pharmacologic agents, e.g. amphotericin, ouabain, onto the respiratory epithelium induces similar changes in in vitro and in vivo PD. We conclude that techniques that have been used to measure permeability and transport in other epithelia may help elucidate modes of action of environmental agents on airways.

Methods of organ culture for human bronchus.

Abstract: Publisher Summary This chapter discusses the methods of organ culture for human bronchus One goal of organ culture is the maintenance of in vivo characteristics and specific cellular relationships Both the human and bovine trachea and bronchus were cultured as 1-cm-square pieces in 60-mm Falcon plastic petri dishes with the epithelial surface uppermost The culture medium was added to just reach the epithelial surface of the explant Normal human bronchial epithelium is composed of a single layer of pseudostratified cells The tall, columnar ciliated cells are the most numerous Tall, columnar mucous cells are of two types: (1) goblet cells whose apices are dis tended with large mucous granules and (2) small mucous granule cells that have tiny mucous granules in the apex and are invisible by light microscopy unless stains for mucosubstances are used The xeno-transplant studies show that the culture-induced metaplastic changes are reversible, because when such CMRL-cultured explants are transplanted into nude mice, the epithelium reverts to normal and columnar differentiation takes place and is maintained for over 1 year

Middle ear epithelia in chronic secretory otitis.

Abstract: • In 60 ears with secretory otitis and mucous effusion, the different kinds of epithelium in biopsy specimens from the promontory and in five postmortem cases from other localities in the middle ear are described. Most frequently, the epithelium was thick, pseudostratified, and ciliated, with pronounced basal cell hyperplasia and increase in goblet cell density. No correlation was found between the amount of effusion and the thickness of the epithelium, the basal cell hyperplasia, and the goblet cell density. In autopsies, many different kinds of epithelium were found, such as one-layered, flat, two- or three-layered, cuboidal, pseudostratified, and columnar epithelium with and without basal cell hyperplasia. The appearance of the epithelium was dependent on the stage of the chronic disease, indicating that the epithelium changes during the course of the disease. ( Arch Otolaryngol 106:593-597, 1980)

Scanning electron microscopical investigations on the respiratory epithelium of the Syrian golden hamster. I. Postnatal differentiation.

Abstract: The postnatal development and differentiation of the tracheal epithelium in Syrian golden hamsters was examined by SEM. Surface structures indicate a proliferative growth for the first 10 days after delivery, but differentiation into a mature respiratory epithelium is still incomplete on the 30th day post partum. Cells with microvilli (less differentiated cells, mucus cell precursors and mucus-producing cells) outnumbered ciliated cells up to the 20th day. The topographical distribution of ciliated cells was different at various stages of development in the pars membranacea, pars intercartilaginea and pars cartilaginea. Depending on the time of their development and differentiation, the different cell types in the respiratory epithelium provide useful information on induced alterations because of the high degree of specialisation on their surface.

Exfoliation of respiratory epithelium in hamster tracheal organ cultures infected with Mycoplasma pneumoniae

Abstract: Hamster tracheal organ cultures were infected with M. pneumoniae and examined sequentially by transmission and scanning electron microscopy to correlate surface with intracellular alterations. Infection was established by culture and the demonstration of morphologically compatible organisms on the mucosal surface. Ciliated epithelial cells developed vacuolization of the apical and subnuclear cytoplasm and eventually fragmented along planes formed by coalescing vacuoles. Non-ciliated cells showed apical swelling and loss of microvilli during the course of infection. After degeneration and sloughing of both ciliated and non-ciliated cells, a flattened layer of intact basal cells covered the submucosa. It is likely that progressive vacuolization of epithelial cells leads to exfoliation of both cells and cell fragments in M. pneumoniae infection. Since organisms frequently are associated with these exfoliated cells, their potential presence in sputum and lavage specimens could prove to be of diagnostic importance.

Mucous membrane of respiratory epithelium.

Abstract: Of the eight epithelial cell types of the airway surface epithelium three are secretory, the mucous, serous and Clara cells: the first two are also found in the submucosal glands. Organ culture results indicate that the pattern of control of the surface cells is different from that of the glands. Our recent studies show that in the surface epithelium Clara and serous cells can quickly convert to mucous as do nonsecretory undifferentiated cells. The balance between the various cell types changes with airway level. The type of glycoprotein within the secretory granules is neutral or acid, sialylated or sulfated, and also shows a regional pattern. Homeostasis is maintained in the normal but the equilibrium is quickly upset by a variety of irritants, infection of drugs. Change in pattern of glycoprotein synthesis depends largely on change of granules. The granules at the cell apex change first. The nature and distribution of the various receptor binding sites is significant in patterns of control. This lability occurs in an intact epithelium and whether or not mitotic activity is increased. With irritation tolerance to stimulus develops. Antiinflammatory agents can protect against some of these cellular and intracellular events. Our organ culture studies and biochemical analysis of secretion complement the tissue studies. Recent studies show that isoproterenol and salbutamol (a nonselective beta agonist and a selective beta 2, respectively) alter the normal mix of cell types and quickly, but that they have different regional specificity.

Cell junctions in squamous epithelium during wound healing in palatal mucosa of guinea pigs.

Abstract: – The nature and distribution of cell junctions of the epithelium of wounded guinea pig palate were .studied. Biopsies, 32 in total, were taken 13, 48, 96, and 120 h after wounding. Desmosomes were present in the wound epithelium throughout the observation period. Primitive desmosomes, indicating de novo formation of desmosomes, were observed at the front of advanced migratory lips (48 h) and in the central region and the wound epithelium after bridging (96 and 120 h). Similarly, de novo formed hemidesmosomes were seen. They occurred along epithelial cell membranes exposed to the fibrinous wound exudate during the migratory lip stages (18 and 48 h) and after epithelial bridging. The observations .suggest that wounding induced changes in the mechanical properties of the tissue. Gap junctions were present in migrating epithelium preferably at the stem of the lips and in the epithelium after bridging, which suggests their participation in regulation of the epithelial cell differentiation. Tight junctions, capable of acting as seals, were absent or fragmentary at best. A relative decrease in the volume density of intercellular spaces in migrating epithelium as compared to intact epithelium, suggests an in vivo tissue reaction.

Respiratory epithelium as an integral part of an odontogenic keratocyst: report of case.

Abstract: A case is reported in which the odontogenic keratocyst that appeared to be a dentigerous cyst associated with an impacted mandibular third molar was found histologically to demonstrate the keratinizing stratified squamous epithelium characteristic of these lesions in direct continuity with ciliated columnar epithelium.

Ultrastructure of terminal respiratory epithelium and prognosis in chronic interstitial pneumonia.

Abstract: Following acute damage, proliferation of granular pneumocytes with subsequent transformation into membranous cells is the basic pattern of repair of the alveolar epithelium. Regarding chronic interstitial pneumonias little is known about the ultrastructural changes of terminal respiratory epithelium and their clinical significance. We studied open lung biopsies from 10 patients showing clinical and light microscopic changes consistent with chronic idiopathic interstitial pneumonia (UIP). We studied the ultrastructure and correlated it with the clinical course of the patients. Only alveolar type epithelium was seen in two cases with a short duration of disease and good response to therapy. Bronchiolar-type epithelium was present in the terminal respiratory units of all other patients with longer duration of disease and less favourable prognosis. Four patients died: all of them showed signs of mucus secretion and keratinization in the terminal respiratory epithelium. Thus in chronic interstitial pneumonia the presence of the alveolar type of epithelium seems to indicate reversibility and that of the bronchiolar type irreversibility of the lesions, while mucous and keratinizing metaplasias apparently occur at a late stage of the disease.

Localization of Peroxidase Activity in Tracheal Epithelium

Abstract: The activity of endogenous peroxidase was demonstrated in light ciliated cells, mature goblet cells, and nonciliated serous cells, but not in basal cells, intermediate cells, dark ciliated cells or immature goblet cells of the upper tracheal epithelium of rats, using the diaminobenzidine method for cytochemical demonstration of peroxidase activity. The peroxidase activity ws the most intense in the epithelium of the first tracheal ring and gradually diminished at lower tracheal levels, becoming extremely faint in the vicinity of the middle of the trachea. The activity was localized in cisternae of rough-surfaced endoplasmic reticulum (r-ER) including the nuclear envelope, some vesicles and saccules of the Golgi complex, secretory granules, and small apical vesicles. It is believed that the basal cells were transformed into the intermediate cells, and some of the intermediate cells were turned into the ciliated cells, while other intermediate cells were differentiated into the goblet cells. The dark ciliated cells proved to be the immature ciliated cells immediately after the transformation from the intermediate cells. In these cells, peroxidase is not yet produced.