Showing papers on "Respiratory epithelium published in 1977"

Surface parasitism by Mycoplasma pneumoniae of respiratory epithelium.

Abstract: Identification of the attachment factor on virulent Mycoplasma pneumoniae organisms which permits surface parasitism of respiratory epithelium was attempted. Brief pretreatment of M. pneumoniae monolayers with protease prevented mycoplasma attachment ot sensitive host cells without reducing viability of the microorganisms. Gel electrophoretic analysis of mycoplasma proteins before and after exposure of intact mycoplasmas to protease revealed the absence of a major protein species (P1) in enzyme-treated preparations while other protein bands with the exception of P2 were virtually unaffected. The absence of P1 correlated with the failure of enzyme-treated mycoplasmas to attach to tracheal explants. P1 regeneration after protease treatment of mycoplasma monolayers was directly associated with reattachment capabilities in M. pneumoniae. Erythromycin inhibited P1 resynthesis, thus preventing resumed attachment activity by mycoplasmas. Lactoperoxidase-catalyzed iodination of intact M. pneumoniae organisms further confirmed that P1 was an external membrane protein and suggested that his surface component was required for the successful membrane-membrane interaction between host and parasite.

Biochemical transformation of regenerating ocular surface epithelium.

Abstract: Several biochemical parameters, including glycogen levels, and the activities of hexokinase, phosphorylase, and lactate dehydrogenase have been compared in regenerating epithelium of conjunctival and corneal origin in rabbits. The study was designed to determine the extent of biochemical transformation of conjunctival into corneal epithelium completed within 6 weeks. Although histological transformation, especially in the case of the chemically damaged eyes, is not. Glycogen and lactate dehydrogenase levels remained well below normal corneal epithelial levels for the period of observation.

Endocrine-like cells of the pulmonary epithelium of the human adult lung.

Abstract: The morphological and histochemical characteristics of endocrinelike cells of the pulmonary epithelium of the right lower lobe of 12 human adult lungs were studied. Few cells were reactive to the argyrophil silver method of Grimelius and of Sevier and Munger and cells with a similar morphology and distribution emitted a green or yellow fluorescence after treatment of the lung epithelium with the amine precursors L-DOPA or L-HTP, respectively. A greater number of cells seems to be demonstrated by electron microscopy. The cells were characterized by small, round secretory granules showing a central dense core and a very thin clear halo between the core and the surrounding membrane. The cells are thought to be related to the endocrine-like cells of the pulmonary epithelium of the human foetal lung and to cells of carcinoids of larger bronchi.

Origin of ciliated alveolar epithelial cells in bleomycin-induced lung injury.

Abstract: Bleomycin is known to induce diffuse pulmonary fibrosis and epithelial metaplasia. The reaction of the alveolar epithelium following a single intravenous or multiple intraperitoneal injections of bleomycin to mice is now examined in a combined morphologic and cytodynamic study. Necrosis of Type 1 cells was observed, followed by proliferation of Type 2 cells, a common reparative process. The proliferated cells transformed to a variety of epithelial forms, including ciliated cells and cells with morphologic features intermediate between alveolar and bronchiolar epithelium. No evidence of cell injury or increased cell division was found in the bronchial epithelium. It is concluded that the metaplastic ciliated epithelial cells are produced by an abnormal reparative process in the alveolar epithelium. The results suggest that, whereas the "resting" Type 2 cell is not vulnerable to bleomycin, in the postmitotic phase the drug may modify the synthetic mechanisms of cellular differentiation and thereby induce metaplasia.

Further observation on the fine structure of a colloid cyst of the third ventricle

Abstract: The fine structure of a surgically excised colloid cyst is described. The cyst was lined by ciliated and nonciliated columnar cells. The nonciliated cells contained secretory material and had a surface coating. In addition, a third type of smaller cell was seen wedged between the columnar cells and abutting on the basement membrane. These cells contained abundant free ribosomes and tonofilaments and displayed well developed desmosomes and half desmosomes. The cyst lining closely resembled the upper respiratory epithelium rather than neuroepithelium, thus supporting the contention that colloid cysts are derived from an endodermal source.

Differences in the attachment of Mycoplasma pneumoniae cells and membranes to tracheal epithelium.

Abstract: Hamster trachea organ cultures were exposed to isolated membranes of Mycoplasma pneumoniae, PI 1428. Attachment, monitored by the uptake of tritiated membranes, was relatively insensitive to neuraminidase pretreatment, unlike the attachment of viable cells. Membrane attachment was optimal when explants were incubated with 50 to 100 micrograms of membrane protein per ml in minimal essential medium broth while gently being rotated (1 rpm) in a roller apparatus for 90 to 120 min at 37 degrees C. Saturation of the receptor sites with viable cells failed to inhibit subsequent membrane attachment. Induction of squamous metaplasia by extended cultivation of tracheal explants in a vitamin A-free medium reduced the content of ciliated cells without significantly affecting total cell viability, but did not alter the attachment of M. pneumoniae membranes. Collectively, the data indicate that the mechanism of attachment of M. pneumoniae membranes to respiratory epithelium is distinct from the receptor site-mediated attachment of M. pneumoniae cells.

Identification of the Schwann cell as a peripheral nervous system cell possessing a differentiation antigen expressed by a human lung tumor.

Abstract: Recent studies of the plasma membrane antigens of a human lung tumor (oat cell carcinoma) indicated that the tumor expressed at least two normal differentiation antigens undetectable in normal respiratory epithelium. One antigen was characteristic of certain endodermally derived epithelial cells of the digestive system; the other antigen was characteristic of certain neural crest-derived cells in the peripheral nervous system. The present studies were undertaken to identify the reactive cell type in the peripheral nervous system. Since similar cells in the rat peripheral nervous system expressed a cross-reactive form of this antigen, and since pure cultures of different rat nerve cell type were available, the following approach was possible. Cultures of pure neurons, pure Schwann cells, pure fibroblasts, neurons and Schwann cells, and neurons, Schwann cells, and fibroblasts were assayed for this antigen with rabbit anti-oat cell carcinoma plasma membrane antiserum absorbed with normal lung and liver. The indirect immunofluorescence method on both whole, viable cell and fixed cell substrates was used. Only Schwann cells expressed the antigen; Schwann cells in the presence of neurons expressed the antigen much more strongly than did pure Schwann cells. It was concluded that the oat cell carcinoma of the lung expressed a differentiation antigen present on Schwann cells.

The morphology of human papillomas of the upper respiratory tract

Abstract: Recurrent squamous papillomas of the upper respiratory tract were examined by light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Surface of the cells is irregular and is covered by numerous stout microvilli. These are shorter and broader than those of cells of the uninvolved mucosa. The villi often seem umbilicated at the apex; the remainder of them, however, are rounded. The epithelium participating in the formation of papillomas shows some maturation of the cells but this does not progress normally. The predominating area is the thickened spinous layer representing the bulk of the lesion. The basal layer shows mildly increased activity but the basement membrane is intact. The cells often are very closely packed but in some areas, more particularly in the deep layer, they are loosely arranged. The intercellular space contains a moderately electron-dense finely fibrillar material. No abnormal mitoses are found. The neighboring univolved epithelium often shows increased growth activity and some inflammation. The larygneal papillomas propably represent an overgrowth of epithelium which may develop following hindered desquamation caused and/or heralded by a chronic inflammatory condition probably of viral origin and may be preceded by epithelial metaplasia and hyperplasia.

Differential Distribution of Ciliated Epithelial Cells in the Trachea of Hamsters: Implications for Studies of Pathogenesis

Abstract: The morphology of the inner aspect of the adult hamster trachea was examined by scanning electron microscopy. Relatively large patches of unciliated cells were observed in the epithelial layer. The patches, which covered several hundreds to thousands of square microns, were most conspicuous on the ventral surface of the trachea, especially in the middle third. The frequency of these areas of unciliated cells, both isolated and in patches, was much greater in hamsters than in mice, rats, or cats. Greatest ciliation in the hamster trachea was observed over the strip of trachealis muscle between the open ends of the cartilaginous rings. Areas with the heaviest ciliation also had the greatest activity of cellular metabolism, as measured by the tetrazolium reduction assay. The attachment of tritium-labeled cells of Mycoplasma pneumoniae was inversely correlated with extensive ciliation, since the greatest numbers of counts were found on the middle third and ventral regions of the tracheal surface. The results of this study suggest that the regional differences in ciliation of respiratory epithelium in hamsters may influence studies of pathogenesis and isolation of M. pneumoniae and that these differences should therefore be considered and controlled in the experimental design.

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

Abstract: 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.

Regulation of the Secretory Cycles of Mucous and Serous Cells in the Human Bronchial Gland

Abstract: The mucin component of human bronchial secretions consists of glycoproteins of high molecular weight, synthesised and secreted both by goblet cells, present in the airway epithelium, and mucous and serous cells of the bronchial glands. Mucus hypersecretion in chronic bronchitis is characterised by an increase in the number of goblet cells and in the size and rate of secretion of the bronchial glands (Reid, 1954, Sturgess and Reid, 1972a).

Effect of squamous metaplasia on infection of hamster trachea organ cultures with Mycoplasma pneumoniae.

Abstract: An organ culture system for hamster trachea was developed for maintenance of the ciliated respiratory epithelium during periods of extended cultivation (i.e., greater than 20 days). Evaluation of five serum types showed that horse serum and fetal calf serum were best for the maintenance of epithelial ciliary activity and morphology. Rings that were opened on one side ("split rings") had the best maintenance of the ciliated epithelium as judged by the retention of ciliary activity and normal histological appearance after 3 to 4 weeks in culture. The in vitro induction of squamous metaplasia was achieved by cultivating explants in Waymouth MAB 87/3 (vitamin A-free) medium, without serum. This system allowed a direct comparison of the effects of Mycoplasma pneumoniae infection in two epithelial types, ciliated pseudostratified columnar and keratinizing squamous. Attachment of 14C-labeled mycoplasmas was more than twofold greater in the normal epithelium. Pretreatment of explants with neuraminidase decreased attachment for both squamous and pseudostratified epithelial surfaces to a similar basal level. Recovery of viable organisms from infected tissue of both epithelial types indicated that the organism titer remained essentially constant during the infection period, but was significantly higher for the pseudostratified ciliated epithelium. These results suggest that specific receptor sites for M. pneumoniae are markedly reduced by the induction of squamous metaplasia and, hence, appear to be specific for the normal respiratory surface containing goblet cells and pseudostratified, ciliated epithelial cells.

Scanning electron microscopic investigations of olfactory epithelium in the chick embryo

Abstract: This paper describes maturation of the surface of the olfactory epithelium of the superior nasal concha of chick embryos from the seventh day of incubation till hatching.

Murine Cytomegalovirus Infection of Epithelial Cells in Mouse Tracheal Ring Organ Culture

Abstract: A differentiated tissue model was used to study the course of cytomegalovirus infection in respiratory epithelium in vitro. Mouse tracheal rings in organ culture were infected with murine cytomegalovirus. Infectious virus in the medium reached average titers of 10(5.5) plaque-forming units/ml by day 17. Infected epithelial cells on the rings contained viral antigen as demonstrated by immunofluorescence staining; light microscopy of these cells revealed enlarged nuclei, cytoplasmic vacuolization, and nuclear and cytoplasmic inclusions characteristic of infection with cytomegalo-virus. Development of viral particles, as visualized by electron microscopy, was similar to that observed in other types of cells.

Histological features of respiratory epithelium of calves held at differing temperature and humidity.

Abstract: The effect of ambient temperature and humidity on the structure of respiratory epithelium of calves was studied. Four calves of each of three experiments were acclimatized to a nonoperational environmental chamber for six days and then exposed to constant extremes of temperatures and relative humidity of one of 30 degrees C --35%, or 27 degrees C--92%, or 5 degrees C--92% respectively in this chamber for eight days each. Five calves (3 and 2) were similarly acclimatized then exposed to 1 degrees C--40%. Nasal swabs were taken from all animals at regular intervals. Swabs of three animals yielded Mycoplasma spp. and one swab yielded the virus of infectious bovine rhinotracheitis. Detailed histological studies of respiratory epithelium of nose, trachea, major bronchus and terminal bronchioli were conducted at four sites. Goblet cells were least in calves held in hot and dry air; calves held in dry air had the least polymorphonuclear cells and the greatest prevalence of hypochromatic cell layers and vacuolation of epithelial cells. Differences between experiments were evident most for sites of trachea and major bronchus.

Scanning electron microscopic study on the distribution of epithelial cells in the Eustachian tube.

Abstract: Canine Eustachian tube epithelium was examined by means of the scanning electron microscope. The part of the tube at the bone-cartilage junction was found to be the most active. It is here that goblet cells and large numbers of ciliated cells were found. Cilia were dense and covered by a mucus blanket. Near the tympanic end of the Eustachian tube, goblet cells were more numerous and ciliated cells less so. Near the pharyngeal end, goblet cells were numerous, while cilia were scanty and not uniform in length. Our findings support the concept that middle ear clearance is carried out by an active muco-ciliary mechanism as in other parts of the upper respiratory system.

Langerhans cells in the epithelium of the bovine forestomach: their role in the primary immune response.

Abstract: Dendritic, migratory, lymphoid cells identical to the Langerhans cells of the epidermis, have been found in the epithelium of the bovine forestomach. They also possess the characteristic Langerhans cell granules. It can be assumed that these epithelial lymphocytes, (or Langerhans cells) as has been reported for the epidermal Langerhans cells, are antigen detectors and therefore form the first line of defence in the general immunological response of the body. The author suggests that the Langerhans cells of the forestomach be named epithelial lymphocytes. The existence of Langerhans cell granules has not yet been reported in the epithelial lymphocytes of the true stomach, intestines and respiratory epithelium.

Ultrastructure of the Respiratory Epithelium in the Lungs of the Newt Triturus cristatus

Abstract: The respiratory epithelium in the lungs of the newt Triturus cristatus has been studied by electron microscopy. The entire pulmonary gas-exchange area is covered by a continuous epithelium, the cells of which are all of the same type and are termed “pneumonocytes”. Typically each pneumonocyte is squamous and has attenuated sheets of cytoplasm which cover the pulmonary capillaries. Its free surface bears microvilli while mitochondria, multivesticular bodies and small inclusions are prominent in its cytoplasm. Many pneuomonocytes send cytoplasmic processes deep into the substance of the lung wall. It is postulated that these processes may help to anchor the epithelium.

Response of pulmonary macrophages to lead.

Abstract: The intratracheal instillation of moderate doses of PbO to Long-Evans strain rats resulted in a significant increase in the number of recoverable pulmonary alveolar macrophages. The viability of recovered cells was remarkably constant throughout the experimental period of 40 days. The results obtained indicate a low order of toxicity of PbO to alveolar macrophages and show that the mucociliary escalator is a significant route of excretion of PbO from the respiratory tract. The in vitro survival of macrophages from PbO-treated rats was significantly reduced. Survival of cells from both treated and control animals was somewhat enhanced by the addition of formalinized lymphocytes to the culture medium. Morphological changes and evidence of phagocytosis are discussed.

Tonofilaments in normal human bronchial epithelium and in squamous cell carcinoma.

Abstract: Tonofilaments in the cells of squamous cell carcinoma of human bronchial epithelium were observed and compared to those in normal bronchial epithelium in 2 patients. In the normal tissue, only small numbers of tonofilaments were observed, and these were found only in the basal cells of the epithelium. In the tumor cells, the quantity of filaments increased considerably. They appeared in the cytoplasm both as branching and anastomosing bundles (tonofibrils) and also as single filaments about 40 A in thickness. These bundles were particularly well developed in the core of narrow cytoplasmic processes of tumor cells. The thickness and appearance of single tonofilaments were similar to those of the cytoplasmic microfilaments also observed in this study. It is suggested that the development of tonofilament bundles in the cytoplasmic processes of tumor cells may provide direct motive force for the deformation of the shape of the cell and potential invasiveness of these tumor cells.

Organ culture-cell culture system for studying multistage carcinogenesis in respiratory epithelium. [Mice]

Abstract: An organ culture-cell culture system was used to demonstrate carcinogen dose-dependent transformation of tracheal epithelial cells in vitro. Tracheal explants were exposed to MNNG (N-methyl-N/sup 1/-nitro-N-nitrosoguanidine) in organ culture. Outgrowths from these explants provided epithelial cell cultures. The numbers of long term epithelial cell cultures and cell lines that were established per explant increased as MNNG exposure concentration increased. At the present time, more cell lines derived from explants exposed to the highest MNNG concentration have produced palpable tumors than cell lines derived from explants exposed to lower MNNG concentrations. No cell lines were established from primaries derived from control explants. TPA (12-0-tetradecanoyl-phorbol-13-acetate), stimulates DNA synthesis in tracheal epithelium in organ culture in a manner simular to that described for mouse skin. Short exposures to TPA not only stimulated DNA synthesis earlier, but the stimulation was greater than that obtained with continuous exposure. At the present time, exposure of tracheal organ cultures to MNNG followed by TPA has resulted in an enhanced production of morphologically altered cells in primary epithelial cell cultures, than exposure to either agent alone.