Giant mitochondria in the seromucous secretory cells of the accessory submandibular gland of the long-haired fruit bat,Stenonycteris lanosus

Giant mitochondria, measuring up to 6.4 μm in diameter, are present in the seromucous secretory cells of the accessory submandibular gland of the long-haired fruit bat, Stenonycteris lanosus. These mitochondria, as well as all of the smaller ones in the same cells, contain in their matrix compartment an abundance of 33 nm threads that probably consist of protein. Some mitochondria, regardless of size, contain 5 nm helical filaments within an expanded crista. Despite their altered morphology, the enlarged mitochondria in the accessory submandibular gland of S. lanosus must be able to function normally in energy metabolism, since the secretory cells in which they are found elaborate numerous secretory granules. © 1993 Wiley-Liss Inc.     

The golgi complex and mitochondria in the secretory cycle of chromaffin cells during the secretory phase

Summary The object of study was the organelles of the rat adrenal chromaffin cell under normal conditions and in hypoglycemic shock caused by insulin injection in the animals, resulting in the active secretion of catecholamines by the cortex of the adrenal gland. The organelles of these cells underwent considerable changes. The Golgi complex became loose and was distributed throughout the cell. Mitochondria, normally few and of granular, rod- and filamentous forms, usually localized around the nucleus, became uniformly distributed in the cell, increased in number, and enlarged in size, and were mainly granular in form.The characteristic changes in the Golgi complex and mitochondria during the phase of active secretion are evidence for their active participation in the secretory process.(Presented by Academician N. N. Zhukov-Verezhnikov) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 61, No. 3, pp. 108–112, March, 1966     

The formation of enlarged and giant mitochondria in the aging process of human hepatic cells.

Measurement of area, circumference and total length of membrane profile of mitochondria of hepatic cells in 61 human biopsy materials (age range 21 to 81 years) have been ultramicrometrically performed on electron micrographs, supplemented by electroncytochemical examination of cytochrome c oxidase activity in some cases. The mitochondria decreased in number after 60 years of age. The first stage of compensation for the numerical loss of mitochondria was achieved by an increase of cristae in each mitochondrion, followed with a five year lag by an increase in their size. Formation of enlarged and giant mitochondria in aging process following the significant decrease in their number, may be considered to be of similar mechanism to polyploidization of the nucleus, whose division is interfered.     

Conditional recombination reveals distinct subsets of epithelial cells in trachea, bronchi, and alveoli

To identify relationships amongst tracheal and alveolar epithelial cells during lung development, we used conditional systems controlled by the rat CCSP and human SFTPC gene promoters to express Cre-recombinase in the developing mouse lung, thereby permanently labeling cells by expression of alkaline phosphatase or green fluorescent protein. When controlled by the rat CCSP promoter, continuous exposure of the fetus to doxycycline caused widespread recombination in conducting airway epithelial cells, including cells of the trachea, bronchi, and bronchioles before birth, and in both conducting and peripheral airways after birth. Neuroepithelial cells, identified by CGRP staining, were never labeled. Recombination and permanent labeling were observed in both ciliated and nonciliated respiratory epithelial cells, demonstrating their derivation from common progenitor cells during lung morphogenesis. Remarkable dorsal-ventral and cephalo-caudal labeling patterns, established before birth, were identified by recombination controlled by the rat CCSP gene promoter. In the trachea, subsets of epithelial cells labeled by the CCSP promoter were organized horizontally along the dorsal-ventral axis of the trachea, where selective labeling of cells juxtaposed to tracheal and bronchial cartilage was observed. In sharp contrast, recombination controlled by the human SFTPC gene promoter identified related cells that were organized in linear patterns along the cephalo-caudal axis of the conducting airways. Conditional expression of Cre-recombinase in the respiratory epithelium provides a useful model for the study of gene expression and function in the mouse respiratory tract and in the lung.     

Expression of a secretory product by microvillous and ciliated cells of the human endometrial epithelium in vivo and in vitro

A monoclonal antibody which identifies a component of post-ovulatoryendometrial secretions is now shown to be expressed within thecytoplasm and on the cell surface of both microvillous and ciliatedepithelial cells. A glandular explantatlon model was developedin order to study the ‘carry over’ of this secretionto the regenerative phase endometriwn. A loss of cytoplasmicantigen was observed in vitro. However, it was retained on thecell surface in a fashion consistent with its expression atthe time of explantation. Mosaicism of expression of this secretorycomponent occurs throughout the secretory-phase and is particularlypronounced at the time of transition from proliferative to secretoryphase. It is conduded that both ciliated and microvillous epithelialcells produce a post-ovulatory secretory component which maybe retained on the cell surface in the absence of hormonal stimulation.     

ELISA for measurement of secretory IgA distinct from monomeric IgA

A micro enzyme-linked immunoassay (ELISA) is described for the quantitation of secretory IgA as distinct from monomeric IgA. The assay is sensitive (linear down to 30 ng/ml) and reproducible (inter-assay variation: 17.0%; intra-assay variation: 11.5%). The assay has the further advantages of rapidity, the ability to handle large numbers of samples, and uses commercially available reagents throughout. Minimal interference from a large (greater than 25-fold) excess of monomeric IgA was observed. The results obtained for serum secretory IgA concentrations by this method correlated well with those reported by other workers for normal control patients, patients with IgA deficiency and patients with liver disease.     

Changes in epithelial secretory cells and potentiation of neurogenic inflammation in the trachea of rats with respiratory tract infections

Summary In rats respiratory tract infections due to Sendai virus and coronavirus usually are transient, but they can have long-lasting consequences when accompanied by Mycoplasma pulmonis infections. Morphological alterations in the tracheal epithelium and a potentiation of the inflammatory response evoked by sensory nerve stimulation (neurogenic inflammation) are evident nine weeks after the infections begin, but the extent to which these changes are present at earlier times is not known. In the present study we characterized these abnormalities in the epithelium and determined the extent to which they are present 3 and 6 weeks after the infections begin. We also determined the magnitude of the potentiation of neurogenic inflammation at these times, whether the potentiation can be reversed by glucocorticoids, and whether a proliferation of blood vessels contributes to the abnormally large amount of plasma extravasation associated with this potentiation. To this end, we studied Long-Evans rats that acquired these viral and mycoplasmal infections from other rats. We found that the tracheal epithelium of the infected rats had ten times as many Alcian blue-PAS positive mucous cells as did that of pathogen-free rats; but it contained none of the serous cells typical of pathogen-free rats, so the total number of secretory cells was not increased. In addition, the epithelium of the infected rats had three times the number of ciliated cells and had only a third of the number of globule leukocytes. In response to an injection of capsaicin (150 g/kg i.v.), the tracheas of the infected rats developed an abnormally large amount of extravasation of two tracers Evans blue dye and Monastral blue pigment, and had an abnormally large number of Monastral blue-labeled venules, particularly in regions of mucosa overlying the cartilaginous rings. This abnormally large amount of extravasation was blocked by dexamethasone (1 mg/day i.p. for 5 days). We conclude that M. pulmonis infections, exacerbated at the outset by viral infections, result within three weeks in the transformation of epithelial serous cells into mucous cells, the proliferation of ciliated cells, and the depletion of globule leukocytes. They also cause a proliferation of mediator-sensitive blood vessels in the airway mucosa, which is likely to contribute to the potentiation of neurogenic inflammation that accompanies these infections.Funded in part by National Institutes of Health Pulmonary Program Project Grant HL-24136 from the US Public Health Service. Dr. Huang is the recepient of an award from the National Science Council of the Republic of China     

Primary culture of mucin-producing cells from chicken trachea

Summary Tracheae obtained from the domestic fowl were incubated with a pronase/EDTA mixture to dissociate the epithelial cells. The freshly isolated cells were placed on collagen-coated coverglasses in RPMI-1640 medium supplemented with 10% fetal bovine serum and incubated in a humidified atmosphere of 5% CO₂ in air at 37°C. Mucin-producing cells as well as basal cells were present in the cultures which reached confluency within 3 d. This primary cell culture system may prove useful for thein vitro study of mucin synthesis and secretion.     

Giant mitochondria in the epithelial cells of the proximal convoluted tubules of diseased human kidneys.

Electron microscopy of 100 renal biopsies obtained at random from patients with various renal disorders revealed gigantic mitochondria in the cytoplasm of the epithelial cells of the proximal tubules in 36 cases (36 per cent). These giant mitochondria are usually round, ovoid, spindle-shaped or rod-shaped often reaching the size of the cell nucleus, and appear singularly and sporadically in the epithelial cell lining of the tubules. Once recognized by electron microscopy they are easily identified in routine histologic preparations and show the same staining characteristics as other mitochondria. In electron microscopy, giant mitochondria have a double limiting membrane, abundant matrical substance, and few remnants or cristae. In addition, they are characterized by (1) intramatrical irregularly branching fibrils approximately 35 A thick, (2) intramatrical bundles of straight filaments approximately 60 to 70 A thick, (3) intramatrical electron-opaque globules up to 0.6 mum., and (4) helical filaments in focally dilated spaces of the outer compartment. The significance of such a remarkable morphologic change of tubular mitochondria and the nature of the unusual components are at present unknown, but an abnormal metabolic condition is considered in its pathogenesis. Nothing specific has yet been found in the relationship between the positive appearance of giant mitochondria and types of renal disorders or clinical and laboratory data. It may be postulated from the present study that "giant mitochondrial tubulopathy" is a rather common, characteristic, and noteworthy change in the histopathology of renal tubule.     

Ultrastructure of metaplastic ciliated cells in human stomach

Summary Intestinal metaplasia of the gastric mucosa occurs commonly in aged Japanese patients and has been discussed in relation to the high incidence of gastric cancer in Japanese. Ciliated cells in the gastric mucosa have frequently been found in association with intestinal metaplasia in the pyloric gland and rarely in the cardiac gland in many Japanese patients, and exceptionally in one Chinese and in one Swedish patient. Electron microscopic examination of 12 Japanese patients has revealed that these structures are not metaplastic stereocilia, but true cilia. Ciliated cells have been found in the basal part of the gastric glands and never in the surface epithelium. The fine structure of the gastric cilia was almost the same as that of normal respiratory cilia. However, in the gastric cilia, most dynein arms were inconspicuous even after tannic acid fixation, indicating that ciliary beating of the gastric cilia is problematic. Abnormal cilia and basal bodies also were found. Ciliated cells have always occurred in association with intestinal metaplasia, therefore this phenomenon might be a type of metaplasia and is named ciliated metaplasia of the gastric mucosa.     

Giant mitochondria in a pleomorphic adenoma of the submandibular gland

A benign pleomorphic adenoma of the submandibular gland was examined by electron microscopy. In some areas, the epithelial cells comprising the tumor formed ductlike structures surrounding a lumen filled with membrane vesicles. The cells actually abutting the lumens had giant mitochondria measuring up to 8 micrometers in diameter; such enlarged organelles were absent from immediately subjacent cells. The giant mitochondria exhibited a variety of cristal arrangements, the most common being a quasireticulate one. They often contained expanded cristae that enclosed a number of helical filaments. Bundles of 14-nm tubules with faintly discernible axial periodicity were frequently present in the matrix compartment, as were amorphous dense inclusions. The basis for the occurrence of giant mitochondria only in duct cells may reside in microenvironmental factors rather than in altered nuclear or mitochondrial genomes.     

Ultrastructural study of the ciliated cells from renal tubular epithelium in acute progressive glomerulonephritis

Light microscopic examination of the renal tubular epithelium of a female with a rapid progressive glomerulonephritis revealed in several areas the presence of cells bearing ciliumlike structures.

At transmission electron microscopy, normal tubular cells appeared to be partially replaced by epithelial cells showing numerous 9×2 cilia and a normally developed basal apparatus. The cilia showed several ultra-structural details (i.e., outer dynein arms, spokes) such as observed in kinocilia of the respiratory epithelium. In addition, a number of poorly differentiated cells showing cilia with a 9 + 0 pattern and at the same time cilia with a 9 + 2 pattern of microtubular arrangement were also seen.

The possible biologic significance of these cilia is discussed.     

Properties of membrane currents in isolated smooth muscle cells from guinea-pig trachea

Tracheal smooth muscle cells were enzymatically isolated from guinea-pig trachea. These cells contracted in response to acetylcholine (0.01–10 M) in a concentration-dependent fashion. Under current-clamp conditions with 140 mM K⁺ in the pipette solution, the membrane potential oscillated spontaneously at around –30 mV. Under voltage-clamp conditions, there appeared spontaneous but steady oscillations of outward current (I _o). On depolarization from a holding potential at –40 mV, three components of outward current were elicited: transient outward current (I _T), steady-state outward current (I _s) and I _o. These three components of outward current reversed around the K⁺ equilibrium potential and were abolished by Cs⁺ in the pipette, indicating that K⁺ was the major charge carrier of these outward currents. All these three components were completely suppressed by extracellular tetraethylammonium (10 mM). Both I _T and I _o were depressed by quinidine (1 mM), 4-aminopyridine (10 mM) and nifedipine (100 nM), but I _s was not affected. I _T and I _o were suppressed by a Ca²⁺-free perfusate with less than 1 nM Ca²⁺ in the pipette, while with 10 nM Ca²⁺ in the pipette, only I _o was suppressed. In both conditions, I _s was not affected by the Ca²⁺-free perfusate. Therefore, it is suggested that I _o, I _T and I _s are separate types of K⁺ current. With Cs⁺ in the pipette, K⁺ currents were almost completely suppressed and a transient inward current was observed during depolarizing pulses. The inward current was not affected by tetrodotoxin and increased when the concentration of extracellular Ca²⁺ was raised, indicating that the current is a Ca²⁺ channel current. Even with a holding potential of –80 mV, the low-threshold inward current could not be observed. The high-threshold Ca²⁺ current was abolished by nifedipine (100 nM) and was enhanced by Bay K 8644 (100 nM). The order of permeation of divalent cations through the Ca²⁺ channel was Ba²⁺ >Sr²⁺ Ca²⁺. Cd²⁺ blocked the Ca²⁺ current more effectively than Ni²⁺. These results may indicate that the Ca²⁺ current of tracheal smooth muscle cells is mainly composed of the current through an L-type Ca²⁺ channel.     

Expression of virus-like particles in normal and transformed gerbil cells

Summary Three types of virus-like particles (VLP) were observed in three of seven gerbil cell lines. One of these cultures was in a non-transformed state and contained R and C-type VLP, while the two others began to express R-type or intracisternal A-type VLP only after spontaneous transformation. These particles seem to be endogenous to the gerbil but do not appear to be directly involved in cell transformation.With 1 Figure     

Stomatin immunoreactivity in ciliated cells of the human airway epithelium

Stomatin is a widely distributed 32kD membrane protein of unknown function. In biochemical studies it is associated with cholesterol+sphingomyelin-rich 'rafts' in the cytomembrane. Genetic studies in C. elegans, supported by microscopic studies in mammalian tissue and co-expression studies in oocytes, suggest a functional link with the DEG/ENaC (degenerin/epithelial Na+ channel) superfamily of monovalent ion channels. Since ENaC channels play a prominent role in the physiology of the respiratory epithelium, we have studied the immunolocalization of stomatin in mature and developing human airway epithelium by means of Western blot analysis, immunocytochemistry, and immunoelectron microscopy. Stomatin immunoreactivity (stomatin-IR) was found in the ciliated cells of the conductive airway epithelium in a distinct distribution pattern with the strongest signal along the cilia. Immunogold labelling revealed immunogold particles at the basal bodies, along the cilia, and at the membrane of the microvilli. The presence of stomatin-IR paralleled the stages of ciliogenesis in airway development, and its appearance preceded the elongation of the axoneme and the cilial outgrowth. Due to its presence in the different cellular locations in the ciliated cell, we suggest that stomatin is involved in various cellular functions. From its ultrastructural position, stomatin could be a candidate for a membrane-associated mechanotransducer with a role in the control of ciliary motility. Stomatin as a raft protein might be a microtubule associated protein moving along the outer surface of the microtubules to its terminal site of action in the cilia. Stomatin-IR in microvilli supports the hypothesis of a co-localization with beta- and gamma- ENaC and, in conclusion, their potential functional interaction to control the composition of periciliary mucus electrolytes.     

Lectin cytochemistry reveals differences between hamster trachea and bronchus in the composition of epithelial surface glycoconjugates and in the response of secretory cells to neutrophil elastase

Hamsters exposed to an intratracheal instillation of human neutrophil elastase (HNE) accumulate an abnormally high number of secretory granules in bronchial but not tracheal epithelial cells. We employed lectin cytochemistry to investigate possible differences in the epithelial cell surface glycoconjugate layer in trachea compared to bronchus which might explain the regional dissimilarity in response to HNE. Portions of glutaraldehyde-fixed trachea and bronchi were incubated in one of several ferritin-labeled lectins prior to embedding for transmission electron microscopy. Lectins from Ricinus communis, Helix pomatia, and Triticum vulgaris bound to the surface of tracheal secretory cells in moderate to profuse amounts, while most bronchial secretory cells showed little or no label with these lectins. Gold-labeled Helix pomatia agglutinin (HPA), a lectin specific for secretory cells, showed a decrease in surface binding to all tracheal secretory cell types within 2 h of HNE instillation, compared to saline controls. In contrast, the majority of bronchial secretory cells showed an HNE-induced increase in surface label from extremely low levels in saline controls. The low levels of lectin binding to bronchial cells, in contrast to the trachea, may indicate the lack of a protective surface glycoconjugate coat, thus explaining the vulnerability of these cells to HNE. The rise in number of accessible HPA binding sites on the surface of bronchial secretory cells exposed to HNE may represent an important event in the pathologic accumulation of secretory granules by these cells.     

Sorting and secretory pathways in exocrine cells

Exocrine secretory cells contain multiple post-Golgi pathways from protein secretion. The major pathway in pancreatic and parotid acinar cells involves protein sorting into storage granules that undergo exocytosis with or without stimulation by secretagogues. This route of release is paralleled by a minor nongranular (but vesicular) pathway that originates by budding from maturing secretory granules. The nongranular pathway carries the same polypeptides that undergo storage in the granules but in different relative amounts. These features indicate that sorting into the stimulus-regulated pathway reflects not only the deposition of secretory proteins into immature granules but may also involve selective aggregation of proteins along with exclusion and vesicle-mediated secretion of other polypeptides that are inefficiently retained. Storage granules represent a distinct compartment of the secretory pathway, as indicated by the specific composition of their limiting membranes. Little is known about processes that maintain the low content and limited diversity of integral proteins of the granule membrane as compared to the membranes with which it fuses during exocytosis and formation. Future studies will examine the role of the nongranular secretory pathway in acinar cells, the branchpoint of pathways that are directed to the apical or basolateral cell surfaces, the structural determinants of secretory sorting, and the distribution and function of specific granule membrane polypeptides.