Showing papers on "Epithelium published in 1980"

Development of the Vertebrate Cornea

Abstract: Publisher Summary The development of the avian cornea involves a remarkable continuum of highly coordinated events. The corneal epithelium is the first of the component tissues to differentiate. This ectodermal derivative, with the help of the lens, secretes the highly ordered primary stroma composed of orthogonally arranged collagen fibrils embedded in a chondroitin sulfate (CS)-rich matrix. The fibroblasts of the avian cornea may produce the first fibronectin to appear within the stroma, although fibronectin is present earlier on the posterior stromal surface and lens. Several striking events occur together during the period of stromal condensation. An enzyme—hyaluronidase—appears, which may remove hyaluronic acid (HA), contributing to the dehydration that begins next to the endothelium and leads to the compaction of the posterior stroma. The dehydration of the stroma and acquisition of transparency are triggered by thyroxine. Thyroxine accelerates interdigitation of endothelial cells and conceivably tells this tissue to begin pumping water out of the cornea. The mitogenic effect of thyroxine on mammalian corneal epithelium in situ is mimicked by fibroblast growth factor (FGF) and epidermal growth factor (EFG), both of which stimulate stratification.

Growth of normal human mammary cells in culture

Abstract: Reduction mammoplasty tissue was used to obtain short-term cultures of human epithelial cell populations. Digestion of tissue with collagenase and hyaluronidase resulted in cell clusters (organoids) resembling ductal and alveolar structures; these could be separated by filtration from the stromal components. Epithelial outgrowth from these organoids was greatly enhanced by the addition of conditioned medium from other human epithelial and myoepithelial cell lines. Additionally, the mammary epithelial growth was stimulated by insulin, hydrocortisone, epidermal growth factor, and steroid hormones. With this enriched nutritional environment, active cell division could be maintained for 1 to 3 months and cells could be serially subcultured 1 to 4 times.

Molecular species of plasminogen activators secreted by normal and neoplastic human cells

Abstract: A survey of 56 normal and neoplastic tissues has shown that plasminogen activators were released by cultured human cells in several molecular weights and their susceptibility to inhibition by antibodies to the normal urinary enzyme, urokinase. Melanoma cells characteristically secreted plasminogen activators which were immunochemically distinct from urokinase and which migrated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis as a prominent, closely spaced doublet with an apparent molecular weight of approximately 70,000 and a minor molecular weight component of approximately 60,000. Enzymes with similar characteristics have been observed in serum-free harvest fluids collected from other neoplastic tissue (a breast carcinoma, a glioblastoma, a malignant teratoma, a uterine sarcoma, and a carcinoma of the renal pelvis) and from normal tissue (8-week embryo fibroblasts, normal esophageal fibroblasts, and one culture of normal adult bladder epithelium). Plasminogen activators released by cells derived from most normal adult tissues, or from a 26-week-old embryo, and from other tumors of ectodermal or mesenchymal origin were inhibited by anti-urokinase antibody and showed a closely spaced doublet with a molecular weight of 60,000 as the most abundant molecular species with no evidence of the enzyme with a molecular weight of 70,000.

HLA-DR-like antigens in the epithelium of the human small intestine.

Abstract: Sections of ethanol-fixed, paraffin-embedded tissue specimens from different parts of the human gastrointestinal tract were stained by an indirect immunofluorescence method with a rabbit antiserum to HLA-DR-antigens from B lymphocytes. A specific staining reaction was seen in a patchy pattern apically in the columnar cells of the normal small intestine, decreasing in intensity from the top of the villi towards the crypts. No HLA-DR-like antigens could be detected in colon or stomach epithelium, whereas cells with the morphology of lymphocytes and histiocytes in the lamina propria and also capillary walls were specifically stained throughout the gastrointestinal tract.

Role of Adherence in the Pathogenesis of Pseudomonas aeruginosa Lung Infection in Cystic Fibrosis Patients

Abstract: A correlation has been demonstrated between the in vitro adherence of Pseudomonas aeruginosa to upper respiratory tract epithelium and colonization of the respiratory tract by this organism. Twenty patients with cystic fibrosis (CF) and 20 age-matched controls were examined in this study. All of the CF patients but none of the controls were colonized with P. aeruginosa at the time of study. P. aeruginosa adherence to isolated epithelial cells, as determined by an in vitro assay, was 19.1 ± 1.1 bacteria per buccal epithelial cell in the CF patients and 2.3 ± 0.3 bacteria per cell in the controls (P

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.

A Permeability Defect of the Retinal Pigment Epithelium: Occurrence in Early Streptozocin Diabetes

Abstract: • The permeability of the blood-retina barrier was tested in rats with early streptozocin-induced diabetes. Two different tracer substances were used: fluorescein sodium and horseradish peroxidase (HRP). After intravenous administration, the ocular distribution of fluorescein was studied by fluorescence microscopy of freeze-dried tissue. A permeability defect of the pigment epithelium to fluorescein was present in one half of the rats four weeks after induction of diabetes. The dye entered the pigment epithelial cells but could not be detected among the photoreceptors. The only dye visible in neural retina was within the retinal blood vessels. For HRP, no fault whatsoever in the blood retina barrier was found: there was no increase of vesicular uptake by the pigment epithelial cells; the tight junctions between pigment epithelial cells were intact as were those between the endothelial cells of retinal blood vessels.

Glandular epithelial induction by embryonic mesenchyme in adult bladder epithelium of BALB/c mice.

Abstract: Tissue recombinants prepared with epithelium of the urinary bladder of adult mice and mesenchyme of the embryonic urogenital sinus were grown as renal capsular grafts in adult male hosts. Under these conditions the bladder epithelium, which is derived embryologically from the urogenital sinus, was induced to form prostate-like acini. The relevance of this observation to McNeal's (1978) hypothesis, that the formation of prostatic acini during the development of human benign prostatic hyperplasia may be a reexpression of the embryonic inductive capacity of the prostatic stroma, is discussed.

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.

Prostatic induction: interaction of epithelium and mesenchyme from normal wild-type mice and androgen-insensitive mice with testicular feminization.

Abstract: The prostate gland develops from the urogenital sinus as epithelial buds projecting into the surrounding mesenchyme. The role of the mesenchyme in this process was determined using sinuses from normal and androgen-insensitive Tfm mice which are deficient in androgen receptors. Epithelium and mesenchyme from both types of sinus were separated and recombined and the recombinants grown in organ culture in the presence of testosterone. Recombinants consisting of normal epithelium and normal mesenchyme developed epithelial buds projecting into the surrounding mesenchyme but no buds were formed in recombinants of epithelium and mesenchyme from mutant mice. In recombinants of epithelium from mutant mice with normal mesenchyme the epithelium developed prostatic buds and the number was similar to that found if normal epithelium was associated with normal mesenchyme. In contrast, normal epithelium combined with mesenchyme from mutant mice failed to form prostatic buds. The results suggested that the mesenchyme determines the development of prostatic buds and that the lack of inductive capacity of the mesenchyme from mutant mice may be due to a deficiency of mesenchymal androgen receptors.

Scanning and transmission electron microscopy on the epithelium of human palatine tonsils.

Abstract: Twelve human palatine tonsils were studied by scanning and transmission electron microscopy. The epithelium lining the tonsillar crypts was shown to be stratified squamous in type, with an extensive system of channels occupying nearly the full thickness of the epithelium. The channels were infiltrated by lymphocytes, plasma cells and mononuclear phagocytic cells. Specialised surface cells, or M cells, were also seen. These had microvilli and surrounded lymphocytes which were brought very close to the crypt lumen. The presence of numerous holes in the crypt epithelium was thought to be an artefact resulting from the delicate nature of the M cells. These showed the organisation of the epithelium related to the function of the tonsil as part of the gut-associated lymphoid tissues. The tonsil has similarities to other gut-associated lymphoid organs but also has its own particular features.

Induction of Nuclear Androgen-Binding Sites in Epithelium of the Embryonic Urinary Bladder by Mesenchyme of the Urogenital Sinus of Embryonic Mice*

Abstract: Mesenchyme of the embryonic urogenital sinus induces epithelium of the embryonic urinary bladder to form prostatic acini. The induced glandular epithelium exhibits nuclear androgen-binding sites, as demonstrated autoradiographically. This suggests that the expression of androgen receptor activity in an epithelium is dependent upon the mesenchyme with which it is associated during development.

Candida albicans Ultrastructure: Colonization and Invasion of Oral Epithelium

Abstract: The colonization and invasion of various animal oral mucosae by Candida albicans were examined in an organ culture model. Scanning and transmission electron microscopy of the oral epithelium between 12 and 30 h after inoculation with the fungus revealed the morphological relationships between host and parasite. Examination of the fungi in thin sections showed five distinct layers in the cell wall of C. albicans within the epithelium, but changes were evident in the organization and definition of the outer cell wall layers in budding hyphae and in hyphae participating in colonization and invasion of the epithelial cells. Adherence of the fungus to the superficial cells of the oral mucosa appeared to involve intimate contact between the epithelial cell surface and the deeper layers of the fungal cell wall. During invasion a close seal was maintained between the invading hyphae and the surrounding epithelial cell envelope, there being no other evidence of damage to the host cell surface except at the site of entry. Within the epithelial cells there was only occasional loss of cytoplasmic components in the vicinity of the invading hyphae. These findings would suggest that enzymatic lysis associated with the invasive process is localized and that the mechanical support provided by surface adherence and the intimate association between the fungus and the epithelial cell envelope may permit growth of Candida on through the epithelium.

Proliferation kinetics of the mouse bladder after irradiation.

Abstract: The proliferative response of the mouse bladder was investigated, using continuous labelling with tritiated thymidine, at various times after a single dose of radiation. Bladder epithelial and vascular endothelial cells were studied. The cell turnover rate in unirradiated epithelium and endothelium was found to be extremely slow (in excess of 1 year). Irradiation with a single dose of 25 Gy resulted in compensatory proliferation of the epithelium but the response was not initiated for many months. At 3 months after irradiation there was little difference from the control proliferation rate, but from 6 to 22 months after irradiation (the end of the study) there was a period of sustained rapid proliferation with the cell turnover time reduced to approximately 1 week. The increase in proliferative activity observed at 22 months was found to be dose—dependent. Endothelial cells in the blood vessels of the submucosa also showed an increased turnover rate after irradiation and the timing of this reponse was found to be similar to that of the epithelium. The onset of compensatory proliferation in both cell types was found to coincide with marked histological and functional changes in the bladder. In this slowly proliferating tissue, the onset of rapid compensatory proliferation after irradiation is delayed and occurs at the time that functional impairment is observed. This supports the postulate that proliferation is unlikely to contribute much to the sparing effect of prolonged fractionated radiotherapy in slowly dividing tissues.

Morphogenesis of branching tubules in cultures of cloned mammary epithelial cells.

Abstract: Morphogenesis (the development of biological form, usually of multicellular organisms or their parts) is generally studied in simple organisms like the slime mould Dictyostelium1, for in mammals even single tissues like the mammary epithelium discussed here appear complex. Mammary epithelium, supported by mesenchymal tissue, forms a system of branching, tubular ducts. During phases of rapid growth these ducts end in solid, swollen ‘end-buds’, and when mature in globular ‘alveoli’2. The mesenchyme influences the morphogenesis of the epithelium and may be essential for this process3,4. An unknown number of cell types are present in both the epithelium and the mesenchyme. One step towards a better-defined ‘model gland’ was taken by Yang et al.5, who recently described three-dimensional, solid, tumour-like outgrowths from clumps of mouse mammary tumour cells cultured in floating ‘collagen gel’6 instead of on a plastic surface. I now describe behaviour retaining some elements of natural morphogenesis, in a cloned line of epithelial cells and thus in the unequivocal absence of mammary mesenchyme—unless mesenchyme can arise from epithelium. On floating collagen gel Rama 25 cells (derived from a rat mammary tumour7) could generate three-dimensional structures which, although often disorganized and tumour-like, included branching, hollow tubules, sometimes with bulbous ends. Thus all the information to specify such organization resided in a single cell type and survived cloning. This raises the possibility of a simple mammalian system in which morphogenetic mechanisms, and their relation to cell differentiation, can be studied as readily as in Dictyostelium.

Chapter 9 Normal Human Prostate Epithelial Cell Cultures1

Abstract: Publisher Summary The chapter discusses the development of procedures to the normal prostate, as either primary explants or fresh tissue. Established culture methods, newly developed techniques, and attention to cellular nutrition have made it possible to isolate reproducibly normal prostatic epithelial cell cultures capable of sustained replication. These cultures are normal epithelial cells based on ultrastructure, karyotype, and inability to grow in soft agar. They were not clonally isolated and are therefore representative of the total neonatal prostatic gland epithelial cell population. The other technique involved replicative epithelial cultures from explanted tissue fragments. This technique is used to initiate prostate cell cultures since 1917. Commonly, epithelial cells migrate from the tissue fragments before the fibroblasts appear. To formulate an effective medium for normal human prostatic epithelial cells, attention must be paid not only to the small-molecular-weight nutrients but to critical growth factors present in fetal bovine serum (FBS).

Accessory cells in teleost branchial epithelium

Abstract: Correlated morphological and cytochemical investigations of the branchial epithelium of the pinfish, Lagodon rhomboides, have revealed a cell type that is invariably associated with chloride cells....

Correlation of early cytodifferentiation of the human fetal prostate and leydig cells

Abstract: The ultrastructural differentiation of the human prostatic epithelium and mesenchyme was studied in early developing glands and correlated with the differentiation of the Leydig cells of the same individuals during the tenth to sixteenth weeks After initial folding of the basal lamina, the epithelial cells began to migrate into the differentiated, condensed mesenchyme at the end of the 10th week, and in the 11th week some of the prostatic outgrowths acquired a lumen The acinar and tubular epithelium in the fetal prostate remained stratified, and adult type simple epithelium was not seen during the period between the 10th and 16th weeks As a sign of incipient secretory activity, a few epithelial cells became polarized, and secretion granules with flocculent or dense content appeared in the Golgi area and in the apical parts of the cells in the 13th week Occasional direct epitheliomesenchymal cell contacts were visible in association with the appearance of the secretory activity Two cell types, not seen in the normal adult prostate, appeared in the epithelium of the primitive glands Their nature and role in the glandular morphogenesis are not clear During this time, the ultrastructural differentiation of the Leydig cells continued and their size and number increased They occupied almost the whole in terstitium by the time secretion granules appeared in the prostatic cells These findings support the current notion that androgens secreted by Leydig cells are the major regulators of prostatic development in man

Inhibition of Rhinovirus Replication in Organ Culture by a Potential Antiviral Drug

Abstract: The compound 2-amino-1-(isopropyl sulfonyl)-6-benzimidazole phenyl ketone oxime (LY122771-72) at a concentration of 0.2 microgram/ml completely inhibited rhinovirus replication in human embryonic nasal organ cultures, although in the absence of virus the compound did not inhibit ciliary activity when used at a concentration of 25 micrograms/ml. When added 26 hr after infection, the compound stopped rhinovirus production in organ cultures that had already started to release virus. Five rhinovirus types available for infection of volunteers and six recently obtained clinical isolates were shown to be more sensitive to LY122771-72 in tissue culture than the rhinovirus type 31 used in the organ culture experiments. These results suggest that this potential antiviral drgu should be evaluated in humans.

Transepithelial migration of human neutrophils: an in vitro model system

Abstract: An in vitro model system for studying transepithelial migration of human neutrophils has been developed. Canine kidney epithelial cells grown on micropore filters form a confluent, polarized monolayer with an average transepithelial electrical resistance of 181 ohms.cm2. Neutrophils in a chemotactic chamber are stimulated to undergo random migration, chemokinesis, or chemotaxis through the epithelium. When stimulated by a gradient of the synthetic chemoattractant fMet-Leu-Phe, significantly more neutrophils traverse the low-resistance epithelium than do under conditions of random migration or chemokinesis. Transmission and scanning electron microscopy of this process reveal that neutrophils traverse the epithelium through the intercellular space. After leukocyte emigration, lateral epithelial cell membranes reapproximate. Neutrophils undergoing chemotaxis can also traverse the polarized epithelium from the basal epithelial surface, which suggests that the chemotactic gradient and not the apical-basal polarity of the epithelial cells determines the direction of transepithelial migration. The data further suggest that (i) the in vitro model of leukocyte transepithelial migration morphologically simulates the in vivo process, (ii) neutrophils more readily penetrate the epithelium when attracted by a chemotactic factor, and (iii) neutrophils can traverse a low-resistance epithelium in the absence of serum and connective tissue factors.

Basal Lamina and Tissue Recognition in Malignant Mammary Tumors

Abstract: The basal lamina is important in normal epithelial morphogenesis and provides a barrier between normal adult epithelium and connective tissue that is not penetrated except by cells of hematogenous origin. Invasion and metastasis by malignant epithelium therefore are thought to require alterations in basal lamina structure or disposition. We have investigated this question in primary mammary tumors and in their spontaneous pulmonary metastases in mice. The commonest structural abnormality of the tumor basal lamina in both sites is hypertrophy in the form of folding, multilayering, or irregular thickening, without observable failure of the barrier function. Interruptions in the continuity of the basal lamina are extremely rare and do not appear to be significant sites of emigration of malignant cells. Mammary tumor epithelium thus maintains an effective basal lamina barrier while invading nonepithelial tissues of either body wall or lung. Even intraarteriolar metastic foci secrete basal lamina between themselves and the arteriolar endothelium, showing that the tumor cells recognize the latter as nonepithelial. Extravascular metastases aggressively invade the pulmonary alveolar air spaces. Here the cells of the two epithelia share the same basal lamina and collaborate to form luminal tight junctions, showing that the tumor recognizes the pulmonary tissue as epithelial but not as nonmammary. Some evidence suggests that a merger of the two different epithelia may involve local fusion of the tumor basal lamina with that of the lung, followed by degradation of the lamina in the fused zone only; similar fusion of basal lamina between adjacent nests within a mammary tumor is also suggested. We conclude that retention of the basal lamina reinforces the tendency of tumor epithelium to grow as cords of cells in contact, while qualitative changes in the lamina contribute to the mode in which the tumor invades epithelial tissues.