Showing papers on "Respiratory epithelium published in 1973"

Goblet Cell Glycoprotein and Tracheal Gland Hypertrophy in Rat Airways: The Effect of Tobacco Smoke with or without the Anti-Inflammatory Agent Phenylmethyloxadiazole

Abstract: A quantitative analysis has been made of tracheal gland size and of histochemical changes occurring in goblet cells of the respiratory epithelium, in rats exposed either to tobacco smoke alone or to tobacco smoke with phenylmethyloxadiazole (PMO). Exposure to tobacco smoke alone causes an increase in goblet cell number with a shift from the production of neutral to acid glycoprotein, mainly sialidase resistant sialomucin but some sialidase sensitive sialomucin and sulphomucin. Acid glycoprotein, and each of its types, appears first at the cell apex. The addition of PMO to the tobacco protects against the increase in goblet cell number but gives no protection against the shift from neutral to acid glycoprotein and causes a larger secretory mass within the goblet cell. In the tracheal gland exposure to smoke from either tobacco alone or tobacco with PMO causes a significant increase in cell size and acinar diameter and a lesser increase in lumen diameter. There is also an increase in the thickness of the gland and its depth. Each of these gland changes is more pronounced in those animals receiving PMO with the tobacco.

The postnatal development of the respiratory system of the opossum. I. Light and scanning electron microscopy

Abstract: The postnatal development of the respiratory system in the opossum has been traced, using 102 specimens divided into 11 groups according to snout-rump length. At birth, the lung is markedly underdeveloped and is represented by a pumitive system of branching airways that end in a number of terminal chambers or sacs. The airways, constituting the conducting portion of the lung, are lined by columnar epithelium that is devoid of cilia and goblet cells. The terminal air chambers contain an extensive capillary bed and are surfaced by squamous epithelium interspersed with scattered cuboidal cells. By the 3 cm stage, bands of smooth muscle have differentiated in relation to the bronchial epithelium and scattered cilia are present in the epithelium of the trachea and bronchi. Air chambers immediately adjecent to established bronchi differentiate further and become incorporated into the bronchial tree and new air chambers develop at the most distal extent of the bronchial system up to the 15.5 cm stage. Numerous spaces lined by squamous epithelium, which represent the first appearance of the arbor alveolaris, appear within the cellular stroma of the lung of the 7 cm opossum. By the 20 cm (juvenile) stage, mature alveoli, containing many vacuolated cells, are present and a thick collagenous lamina has developed between the pleura and the lung parenchyma.

Toxic effects of oxygen on cultured human neonatal respiratory epithelium.

Abstract: Extract: Explants of tracheal epithelium from each of six human neonates were exposed to both 80% and 20% oxygen under otherwise identical culture conditions. Cessation of ciliary movement and carbon particle transport occurred after 48–96 hr of exposure to 80% oxygen, but not after 168 hr of exposure to 20% oxygen. This alteration of ciliary function was related temporally to squamous metaplasia, or to degeneration and sloughing of cells from the surface epithelium. Explants secreted more mucin and lysozyme during the first 24–72 hr of culture in 80% oxygen. Thereafter, diminished secretion was observed, apparently related to loss of goblet cells from the surface epithelium and failure to discharge the secretory products of submucosal glands. These findings indicate that high oxygen concentrations at atmospheric pressure alone can cause marked alterations of structure and function in neonatal large airways epithelium. Onset of these changes corresponds to the time when the earliest clinical and cytologic evidence of bronchopulmonary dysplasia has been detected, suggests that similar oxygen-induced changes are produced in vivo. Loss of mucociliary function may be an important pathogenetic component of bronchopulmonary dysplasia. Speculation: Organ culture of human large airways epithelium appears to be a useful model for study of pulmonary oxygen toxicity. Studies of oxygen concentrations and duration of exposure tolerated by human respiratory epithelium, the cellular mechanisms of oxygen-induced alteration, and the use of pharmacologic agents to prevent or delay onset of toxic changes may be facilitated by using this in vitro technique.

Ultrastructural morphology of the normal nasal respiratory epithelium of the mouse

Abstract: The nasal respiratory epithelium of the mouse has been studied at the ultrastructural level. The tissue was found to be a rather typical pseudostratified columnar ciliated epithelium, superficially different but basically similar to tracheal and bronchial epithelium in the same species, and clearly similar in most respects to that of other mammals. Four cell types were distinguished: ciliated columnar, secretory (goblet), intermediate, and basal. The ciliated cells, which exhibited typical surface cilia and microvilli, were characterized by a distinct stratification in the arrangement of subcellular components in their supranuclear cytoplasm. Beginning at the apical end and proceeding basally, the following strata were seen: an ectoplasmic region relatively free of organelles; an area rich in vesicular and tubular membrane profiles; a mitochondrial zone; a layer rich in ribosomes and polyribosomes; and a stratum of Golgi complexes. Secretory (goblet) cells were observed at various stages of secretion droplet accumulation. Cells in the earliest stage, characterized by a dense content of sER in the supranuclear cytoplasm, were similar to the “non-ciliated” cells of the mouse's lower respiratory tract. Some of the secretory cells contained dilated cisternae of rER which were engorged with a relatively electron-dense material. The possible significance of these inclusions is discussed. Unlike the other cell types, intermediate and basal cells displayed no features indicative of specialized function.

Localization of Benzo]a]pyrene-3H and Alterations in Nuclear Chromatin Caused by Benzo[a]pyrene-Ferric Oxide in the Hamster Respiratory Epithelium

Abstract: The intratracheal instillation of benzo[α]pyrene (BP)-Fe2O3 in the Syrian golden hamster caused a number of changes in nuclear structure. A selective increase in the cross-sectional area of nuclei of basal cells was observed in multiple focal areas in the tracheal epithelium. This increase represented an enlargement in the cross-sectional area of euchromatin and a dispersion of the heterochromatin. In short-term organ culture of tracheas, incubation with BP-3H caused labeling of nuclear and cytoplasmic sites in mucous, basal, and ciliated cells. Quantitative light microscopic autoradiography revealed that prior in vivo administration of unlabeled BP caused a subsequent increase in the in vitro binding of BP-3H to epithelial cells. The total binding of BP-3H to epithelial cells was inhibited either by the addition of 7, 8-benzoflavone to the incubation medium or by incubation at 0°. These results suggest that enzymatic activation of BP must occur before BP can be bound. The nuclear localization of BP-3H was primarily in the heterochromatin, as determined by electron microscopic autoradiography.

What is "epithelium"?

Abstract:  Maximum cell-to-cell contact.  Minimum extracellular material.  Cell junctions: Several types of junctional specializations unite adjacent epithelial cells (tight junctions, desmosomes and gap junctions).  Supported by basement membrane (basal lamella).  Avascular: There are no blood vessels within the epithelial layer.  Derived from all embryonic germ layers, including endoderm, mesoderm and ectoderm  With the exception of endocrine glands,