Showing papers on "Epithelium published in 1984"

Monoclonal antibodies to human intermediate filament proteins. II. Distribution of filament proteins in normal human tissues.

Abstract: Monoclonal antibodies generated against different human intermediate filament (IF) proteins were assayed on fixed, embedded tissue by the biotin-avidin-immunoperoxidase method for evaluation of the tissue specificity of these antibodies. An antibody (43 beta E8) made to fibroblast IF protein stains mesenchymal tissue such as endothelium, histiocytes, stromal fibroblasts, and Schwann cells but does not stain epithelium, skeletal muscle, lymphocytes, or neurons. Three different anti-cytokeratin antibodies decorate epithelium in three unique patterns. One (35 beta H11) stains all nonsquamous epithelium but fails to recognize squamous epithelium. Antibody 34 beta E12 stains the full thickness of squamous epithelium and ductular epithelium but does not react with hepatocytes, pancreatic acinar cells, proximal renal tubules, or endometrial glands. Antibody 34 beta B4 stains only the suprabasal portion of squamous epithelium. None of these three anti-cytokeratin antibodies reacts with nerve or mesenchymal tissue. Two anti-neurofilament antibodies recognize only neurons, failing to react with epithelial or mesenchymal tissue. We conclude that these anti-intermediate filament antibodies can be used as tissue-specific markers. Neoplasms retain the same intermediate filament patterns as the normal parental tissue; therefore, these antibodies can be used as diagnostic aids in surgical pathology.

Epithelial mouse mammary cell line exhibiting normal morphogenesis in vivo and functional differentiation in vitro

Abstract: An epithelial cell line, designated COMMA-1D, was derived from mammary tissue of BALB/c mice in the middle of pregnancy. This line, in continuous cell culture for 12 months, exhibits several characteristics distinctive of normal mammary epithelial cells, including induction of casein synthesis in vitro and normal duct morphogenesis in the cleared mammary fat pads of syngeneic mice. The cells also form domes in high density culture and are positive for keratin intermediate filaments by indirect immunofluorescence. COMMA-1D cells have a near diploid number of chromosomes and do not grow in suspension culture or produce tumors in syngeneic hosts. This cell line should prove useful for studies examining the regulation of normal cellular differentiation of mammary cells as well as transformation of epithelial cells to the preneoplastic and neoplastic phenotypes.

Basement membrane components in healing rabbit corneal epithelial wounds: immunofluorescence and ultrastructural studies.

Abstract: The nature of the substrate that supports epithelial migration in vivo is of interest, particularly with respect to mechanisms of wound healing. Immunofluorescence and electron microscopy were used to search for common substrate components in prototype rabbit corneal wounds: epithelial scrape wounds, in which the corneal or conjunctival epithelium migrated over the denuded lamina densa of the corneal basement membrane (CBM), and superficial keratectomy, in which the corneal epithelium migrated over a bare stroma without CBM. The corneal epithelium moved rapidly over the CBM or stroma to cover the defect within 2-3 d, whereas the conjunctival epithelium required 1-2 wk. In all wounds, fibronectin and fibrin/fibrinogen were deposited onto the bare surface within 8 h after wounding and persisted under the migrating epithelium until migration was complete. Bullous pemphigoid antigen (BPA), a normal component of the CBM, was removed with the epithelium upon scrape wounding and reappeared in the CBM after migration was completed. In contrast, the conjunctival epithelium had a continuous subepithelial band of BPA out to the migrating tip. Laminin, also a normal component of the CBM, was not removed in the scrape wounds, indicating that the region of least resistance to shear stress was between the BPA and laminin layers. Laminin was removed by superficial keratectomy and was not detectable under the leading edge of the migrating cells. Laminin and BPA were restored in the CBM by 2-4 wk. Type IV collagen could not be detected in normal CBM, but was conspicuously present in conjunctival basement membrane and in blood vessels. Focal bands of type IV collagen did appear in the newly synthesized CBM 2-4 wk after keratectomy. These results argue that BPA, laminin, and type IV collagen are not essential for the migration of corneal epithelium during wound healing and support the hypothesis that fibronectin and fibrin/fibrinogen are the common, perhaps the essential, components of the provisional matrix that serves as a substrate until the permanent attachment components are regenerated.

Pathogenesis of tears of the retinal pigment epithelium.

Abstract: This report confirms a previous report that elderly patients with serous detachments of the pigment epithelium prior to and after developing a pigment epithelial tear at one border present a characteristic ophthalmoscopic and fluorescein angiographic appearance. Evidence is presented that subpigment epithelial choroidal neovascularisation and not irregular separation of the basement membrane from its pigment epithelium is the primary cause of the detachment and tear in the pigment epithelium.

The human thymic microenvironment.

Abstract: Publisher Summary Monoclonal reagents have made people able to phenotypically identify four major regions of the human thymus microenvironment: the thymic capsule, interlobular septae and stroma, the subcapsular cortex, the cortex, and the medulla TE-4 + and TE-3 + thymic epithelium constitute HLA + , Ia + subsets of thymic epithelium that are candidates for cell types of the human thymic microenvironment that might participate in conferring major histocompatability complex (MHC) restriction to maturing T lymphocytes TE-4, anti-p19, and BB TECS antibodies are thymic epithelial lineage markers; they all react with the basal layer of squamous epithelium of various organs The concept that thymic epithelium is constantly differentiating in the developed thymus is suggested by the coexpression of TE-4, TE-8, TE-16, and TE-15 antigen by layers of squamous epithelial keratinocytes and by thymic epithelium Three phases of thymic microenvironment development can be defined The first phase is during early fetal development when mesodermal-derived fibrous tissue induces endodermal and ectodermal-derived thymic epithelium to proliferate and mature The second phase occurs between 9 and 15 weeks of fetal development when the thymic primordia are colonized by blood-borne thymocyte precursors Presumably during this stage, thymic epithelium promotes bone marrow cell colonization of thymus by producing chemoattractant molecules The third phase of thymic microenvironment development consists of that period of time when the thymic microenvironment contributes to various stages of intrathymic T cell functional maturation These functions involve participation in generation of the T cell repertoire, generation of MHC restriction, and the production of soluble thymotrophic factors—such as thymosinal, thymopoietin, and thymulin

Coexpression of Simple Epithelial Keratins and Vimentin by Human Mesothelium and Mesothelioma in Vivo and in Culture

Abstract: We have determined the intermediate filament proteins present in normal and malignant mesothelium in vivo. Pure sheets of normal lung mesothelium were obtained by transfer to agarcoated slides or by gentle scraping and cytocentrifugation. Cytoplasmic filament networks in the mesothelium were labeled via indirect immunofluorescence both by anti-Mr 40,000 keratin and anti-vimentin antisera. Two-dimensional gel electrophoresis of the Triton:high-salt-insoluble proteins of normal lung mesothelium disclosed the presence of vimentin and all but the largest (Mr 55,000) of the four simple epithelial keratins synthesized by mesothelial cells in culture. Samples of three peritoneal and three pleural mesotheliomas were found to contain either all four simple epithelial keratins or all but the Mr 55,000 keratin. Notably, none of the keratins characteristic of stratified and many glandular epithelia and their malignant forms was present in these mesotheliomas. Two mesothelioma samples from which the tumor cells could be obtained free of other cell types were found to contain vimentin as well as simple epithelial keratins and to synthesize these same proteins during short-term culture. None of the mesotheliomas placed in culture grew progressively in medium optimal for the growth of normal mesothelial cells. These data demonstrate that malignant mesothelial cells preserve the normal pattern of intermediate filament protein synthesis, including coexpression of simple epithelial keratins and vimentin, and suggest the use of this characteristic as an aid in the identification of cells of mesothelial origin.

The mononuclear phagocyte system of the mouse defined by immunohistochemical localisation of antigen F4/80: macrophages associated with epithelia.

Abstract: The tissue distribution of the murine macrophage-specific antigen F4/80 has been analysed using an immunohistochemical technique. The antigen is observed on all known macrophage populations (including Kupffer cells and bronchoalveolar macrophages) and is absent from any cell types that are definitely not mononuclear phagocytes. Microglial cells from brain express F4/80. F4/80+ macrophages observed associated with epithelia can be divided into two categories, intraepithelial and periepithelial. The former includes epidermal Langerhans cells and cells with similar morphology in other stratified squamous epithelia (cervix, oesophagus), pseudostratified epithelium (trachea), transitional epithelium of urinary bladder, and simple epithelia lining various ducts (salivary gland, common bile duct, tracheobronchial gland). Periepithelial F4/80+ cells, apparently spread immediately below the basal lamina, are associated with simple epithelia throughout the gastrointestinal, respiratory, and male and female reproductive tract as well as the brain ependyma. A major class of periepithelial F4/80+ cells is associated with capillaries throughout the microcirulation. The role of these macrophage populations in control of epithelial function is discussed.

Tissue polypeptide antigen (TPA) is related to the non-epidermal keratins 8, 18 and 19 typical of simple and non-squamous epithelia: re-evaluation of a human tumor marker.

Abstract: Because of the broad clinical interest which tissue polypeptide antigen (TPA) has attracted as a tumor marker, human cell lines and human tissues have been analyzed for TPA expression using immunofluorescence microscopy. Epithelial cell lines including HeLa, MCF-7, and A-431 are recognized by TPA antibodies whereas human lines of non-epithelial origin are not. The positive staining patterns coincide with keratin-type intermediate filaments of the cytoskeleton. On tissue sections a subset of epithelial cells including uterine epithelium, bile duct cells in liver and tumor cells in breast carcinoma are strongly positive; cells of the squamous epithelia of skin and tongue as well as cells of non-epithelial origin are negative. In immunoblots of human epidermis, human tongue mucosa, human hair follicles, Detroit 562 cells, HeLa cells, MCF-7 and RT-4 cells, only keratins 8, 18 and 19 show TPA antigenicity. Conversely a TPA preparation is recognized by various antibodies known to react with keratins, including alpha-IFA, KG 8.13.2 and two antibodies which recognize keratins 18 (CK2) and 19, respectively. Our results thus relate TPA to human keratins 8, 18 and 19 which are known cytoskeletal components in both normal and malignant epithelial cells of simple and non-squamous origin. We speculate that the elevated levels of circulating TPA antigenicity present in the sera of patients with carcinoma, which are often used to monitor tumor progression, correspond to soluble proteolytic fragments originating from this particular keratin subgroup.

Effects of vitamin A-deprivation on hamster tracheal epithelium. A quantitative morphologic study.

Abstract: The effects of vitamin A-deprivation on the tracheal epithelium were studied in 35-day old hamsters that had been raised since birth on a vitamin A-deficient diet. Colchicine and3HTdR were given 6 hours before death and the proliferative activities of basal cells and mucous cells were quantified separately by3HTdR labeling indices and mitotic rates. Vitamin A-deprivation decreased replication of basal cells and mucous cells in tracheal epithelium which showed minimal morphologic change. The mitotic rates and labeling indices were reduced 3 to 4-fold in basal cells and 14-fold in mucous cells (analyzed as percent of total number of each cell type) compared with controls. Thus, replication of mucous cells was more inhibited by lack of vitamin A, than replication of basal cells. The disparatehypoplasia of basal cells and mucous cells in epithelium showing minimal change, resulted in a relative increase in the proportion of basal cells and a relative decrease in the proportion of mucous cells, which could be erroneously interpreted as “basal cell hyperplasia”. Proportions of preciliated and ciliated cells were also decreased compared to controls. At foci of stratification and epidermoid metaplasia, cell replication rates were increased over controls and more than 70% of all mitotic activity was associated with “non-basal” cells. Genesis of these lesions The opinions and assertions contained herein are the private views of the authors and are not to be construed official or as reflecting the views of the Department of Defense The experiments reported herein were conducted according to the principles set forth in the “Guide for the Care and Use of Laboratory Animals” Institute of Laboratory Animal Resources, National Research Council, DHSW Publ. No. 78-23 This is contribution No. 1554 from the Cellular Pathobiology Laboratory of the Department of Pathology, University of Maryland School of Medicine was coincident with cell death and cell loss. The histogenesis of stratification and epidermoid metaplasia was characterized. Morphological evidence indicated that these lesions were closely related histogenetically and were composed, for the most part, of altered mucous cells which expressed dual phenotypes i.e. keratinization and mucus synthesis.

Phenotypic characterization and ontogeny of mesodermal-derived and endocrine epithelial components of the human thymic microenvironment.

Abstract: Using murine monoclonal antibodies TE-4 and TE-7 raised against human thymic stroma, we identified two distinct and mutually exclusive thymic microenvironment components: the thymic endocrine epithelium (TE-4+) and mesodermal-derived fibrous stroma (TE-7+). TE-4-reactive epithelium did not react with antibody TE-7, contained thymosin alpha 1 and keratin, and expressed other known markers of thymic endocrine epithelium (A2B5 and p19). Moreover, TE-4+ thymic epithelial cells strongly expressed class I (HLA-A, -B and -C) and class II (Ia-like) major histocompatibility complex (MHC) antigens. In contrast, TE-7+ thymic fibrous stroma did not react with antibody TE-4, did not contain thymosin alpha 1 nor keratin, and did not express the thymic endocrine epithelium markers A2B5 and p19. TE-7+ thymic stromal cells weakly expressed class I and did not express class II MHC antigens. Both TE-4+ and TE-7+ thymic microenvironment compartments were identifiable in thymus from 7 wk gestation through adult life. At 7 wk fetal gestation, TE-7+ stroma surrounded a cylindrical TE-4+, A2B5+ thymic epithelial rudiment. Between 10 and 15 wk fetal gestation, TE-7+ thymic stroma surrounded early thymic lobules. By 15 wk fetal gestation, antibody TE-4 defined subcapsular cortical and medullary zones of endocrine thymic epithelium, while antibody TE-7 bound to interlobular fibrous septae, vessels, and thymic fibrous capsule. While otherwise specific for endocrine thymic epithelium, antibody TE-4 reacted with the basal layer of squamous epithelium in skin, tonsil, conjunctiva, and upper esophagus.

Connective tissue influences on patterns of epithelial architecture and keratinization in skin and oral mucosa of the adult mouse

Abstract: Epithelial-mesenchymal interactions play an important role during embryogenesis but it is uncertain whether such interactions influence the maintenance of epithelial structure in the adult To examine this problem, separated epithelial and connective tissue components of skin and mucosae from various regions of adult mice were homoor heterotypically recombined and transplanted to histocompatible hosts The patterns of tissue architecture and keratinization of the resultant epithelia were examined for changes indicative of mesenchymal influences on the epithelial phenotype Each type of epithelium, in some recombinations, fully conserved its normal pattern of phenotypic expression indicating that subepithelial connective tissue from all regions is permissive and that regionally-specific connective tissue influences are not necessary for conservation of epithelial specificity In other recombinations, however, the epithelium acquired features of tissue architecture or keratinization typical of the epithelium normally associated with the connective tissue component, indicating directive influ ences from the connective tissue The patterns of epithelial response observed suggest that there may be separate connective tissue influences on epithelial architecture and cytodifferentiation and that there is a regionally-related variation in the competence of epithelia to respond to these influences

The effect of estrogen, progesterone, thyroxine, and human placental lactogen on DNA synthesis of human breast ductal epithelium maintained in athymic nude mice

Abstract: Specimens of human breast tissues from the periphery of excised benign tumors, obtained from 17 pre-menopausal patients, were processed into slices and transplanted subcutaneously to 122 female Balb/c athymic nude mice. Subsequently, the host mice were treated with estrogens, progesterone, thyroxine, and human placental lactogen (HPL) alone or in combination. Growth of the ductal epithelium within the human breast transplants, as a function of the hormone treatment, was assessed by 3H-thymidine autoradiographic analysis, i.e., the number of 3H-thymidine radiolabeled ductal cells per unit area of ductal epithelium (labeling index [LI]). The administration of estrogen or thyroxine alone significantly increased the LI. Progesterone or HPL treatments alone did not substantially influence LI. HPL treatment, but not progesterone or thyroxine treatments significantly enhanced the stimulatory effect of estrogen on LI. The athymic nude mouse as host to human breast tissues in these in vivo/ex vivo studies, has been instrumental in producing information that effectively increases understanding of the hormonal factors influencing DNA synthesis in human breast ductal epithelium.

Gap junctions in several tissues share antigenic determinants with liver gap junctions.

Abstract: Using affinity-purified antibodies against mouse liver gap junction protein (26 K), discrete fluorescent spots were seen by indirect immunofluorescence labelling on apposed membranes of contiguous cells in several mouse and rat tissues: pancreas (exocrine part), kidney, small intestine (epithelium and circular smooth muscle), Fallopian tube, endometrium, and myometrium of delivering rats. No reaction was seen on sections of myocardium, ovaries and lens. Specific labelling of gap junction plaques was demonstrated by immunoelectron microscopy on ultrathin frozen sections through liver and the exocrine part of pancreas after treatment with gold protein A. Weak immunoreactivity was found on the endocrine part of the pancreas (i.e., Langerhans islets) after glibenclamide treatment of mice and rats, which causes an increase of insulin secretion and of the size as well as the number of gap junction plaques in cells of Langerhans islets. Furthermore, the affinity purified anti-liver 26 K antibodies were shown by immunoblot to react with proteins of similar mol. wt. in pancreas and kidney membranes. Taken together these results suggest that gap junctions from several, morphogenetically different tissues have specific antigenic sites in common. The different extent of specific immunoreactivity of anti-liver 26 K antibodies with different tissues is likely due to differences in size and number of gap junctions although structural differences cannot be excluded.

Localization of Aldose Reductase in the Human Eye

Abstract: The presence of the enzyme aldose reductase is increasingly being linked to diabetic complications. The distribution of this enzyme in human cornea, lens, retina, and optic nerve has been studied using specific antibodies against purified human placental aldose reductase raised in both rabbit and goat. The antisera from both animals gave equal, specific reactions. In frozen sections of ocular tissues, significant aldose reductase localization was reproducibly demonstrated in the endothelium and epithelium of the cornea and in the basal cell layers of the conjunctiva. In the lens, staining was observed in the epithelium and superficial lens fibers. In retinal sections, the presence of aldose reductase was demonstrated in the Mueller9s cells, especially near the inner limiting membrane. It was also found in some ganglion and cone cells. In the optic nerve, positive staining was observed in the axon. All other cells of the tissues examined revealed Only weak, nonspecific Staining.

Monoclonal antibodies with different specificities against cytokeratins. An immunohistochemical study of normal tissues and tumors.

Abstract: Monoclonal antibodies against cytokeratins, isolated from human callus, were prepared Here we describe the characterization of three of these monoclonal antibodies (Clones 77, 78, and 80) with special emphasis on the staining characteristics of a number of normal epithelial tissues and a series of tumors On thin sections and in immunoblotting experiments our monoclonal antibodies showed different specificities In immunoblots Clone 80 stained more bands in preparations of cytokeratin from callus, cultured keratinocytes, and a metastasis of a lung carcinoma than Clones 77 and 78 In this last cytokeratin preparation Clones 77 and 78 each stained a separate band not stained by Clone 80 In normal tissues Clone 80 stained all types of epithelia except myoepithelium and podocytes of glomeruli Clone 78 stained mainly squamous epithelium Clone 77 stained differentiated squamous epithelium, transitional epithelium, ductal epithelium, and parenchymatous epithelium These results confirm the heterogeneity of cytokeratins In neoplasms Clone 77 was positive with adenocarcinoma and squamous cell carcinoma Clone 78 stained squamous cell carcinoma and well-differentiated adenocarcinoma Clone 80 stained all epithelial tumors, including anaplastic carcinoma, and is therefore useful in tumor diagnosis

Remodelling of the basement membrane: morphogenesis and maturation.

Abstract: We have analysed the reciprocal interactions between mouse embryo submandibular epithelium and mesenchyme which result in branching morphogenesis of the epithelium The interactions modify the composition and metabolism of the basal and reticular laminae which comprise the basement membrane lying between these tissues The mesenchyme remodels the basement membrane by depositing a type I collagen-rich matrix on the basal lamina and by producing a neutral hyaluronidase, which degrades hyaluronate and chondroitin sulphate, components of this basal lamina By analogy with mouse mammary epithelial cells, the submandibular epithelial cells have a heparan sulphate-rich proteoglycan on their cell surfaces which is anchored to the cells The extracellular domain of this integral membrane proteoglycan binds to interstitial collagen Interfering with the collagen-proteoglycan interaction appears to reduce the morphological stability of the cells Together with other processes, including epithelial cell proliferation, this remodelling leads to branching epithelial morphogenesis Basement membrane remodelling may be a general process for regulating cell behaviour during development and is one of the mechanisms of morphogenetic tissue interaction Remodelling may also cause maturation of basement membranes from a dynamic state of high turnover in the embryo to their persistence and stability in the adult organism

Restoration of mucociliary tracheal epithelium following deprivation of vitamin A. A quantitative morphologic study.

Abstract: In order to learn more about the respective roles played by basal cells and mucous cells in the maintenance of tracheal mucociliary epithelium, cell kinetics and epithelial cell morphology were characterized over a 7-day period, during which dietary vitamin A was restored to previously deprived hamsters. Hamsters were reared from birth to 35 days of age on vitamin A-replete or deficient diets. Deprived hamsters were made replete by 5 mg vitamin A-acetate orally, plus a vitamin A-replete diet. Colchicine and 3HTdR were given 6 h before death. The numbers of basal cells, mucous cells, preciliated cells and ciliated cells, and mitotic rates (MR) and labeling indices (LI) of basal cells and mucous cells, were quantified in glycol methacrylate sections stained with PAS-lead hematoxylin. Vitamin A-deprivation decreased replication of basal cells and mucous cells in tracheal epithelium which showed minimal morphological change. The proportion of basal cells was increased and proportions of mucous, preciliated and ciliated cells were decreased. Following restoration of vitamin A to the diet, the basal cell MR remained below control level throughout the experimental period, but the mucous cell MR started to rise on day 2-replete, and on day 3-replete and thereafter the mucous cell MR was within the control range. Basal cell and mucous cell LI's showed similar trends. Preciliated cells were reduced or absent in vitamin A-deprived epithelium. Their number had risen by day 3-replete and thereafter they were generated within the control range. These cells matured into ciliated cells. By day 4-replete, the proportion of basal cells had decreased markedly and the proportions of mucous cells, and preciliated plus ciliated cells had increased, so that at this time cellular proportions were within or near control values. This trend continued so that by day 7-replete, a nearly normal mucociliary epithelium was restored. The results show that vitamin A-levels modulate replication rates of basal cells and mucous cells and indicate that mitotic division of mucous cells is a prerequisite for the genesis of preciliated cells and new mucous cells and for restoration of the mucociliary epithelium following deprivation of vitamin A in the diet.

The canine vomeronasal organ.

Abstract: The vomeronasal organ was studied in mature dogs with the optical, transmission electron, and scanning electron microscopes. The canine vomeronasal complex is structurally well developed. Large blood vessels are present deep to both the lateral, 'non-receptor' and medial, 'receptor' epithelia. In addition to the unmyelinated vomeronasal nerves in the lamina propria deep to the 'receptor' epithelium, numerous nerves containing both myelinated and unmyelinated fibres are present deep to the 'non-receptor' epithelium. The 'non-receptor' epithelium consists of basal cells, ciliated and non-ciliated columnar cells, and globular cells packed with mitochondria. Contained within the 'non-receptor' epithelium are leucocytes, plasma cells, and nerve endings. The 'receptor' epithelium consists of basal, sustentacular, and ciliated receptor cells. The microtubules in cilia of the receptor cells do not appear to have dynein arms or radial spokes.

Comparison of the ability of basement membranes produced by corneal endothelial and mouse-derived Endodermal PF-HR-9 cells to support the proliferation and differentiation of bovine kidney tubule epithelial cells in vitro.

Abstract: The proliferation and morphological differentiation of bovine kidney collecting-tubule epithelial cells has been examined as a function of substrata and plasma factors. Collecting kidney tubule explant maintained in vitro gave rise to two distinct cell populations; one was composed mostly of fibroblastic cells whereas the other was epithelioid (EP cells). The proliferation of fibroblastic cells when exposed to serum-supplemented medium was best expressed when cells were maintained on a basement membrane produced by bovine corneal endothelial cells. This basement membrane has a composition, which in previous studies has been shown to favor the proliferation of mesenchymal cells. In contrast, the proliferation of EP cells was best expressed when cells were maintained on a basement membrane produced by the mouse-derived endodermal cell line PF-HR-9 (HR-9-BM). This basement membrane has a biochemical composition very similar to the basement membrane underlying the kidney tubules. Although the fibroblast confluent monolayer maintained on bovine corneal endothelial cell extracellular matrix did not undergo morphogenesis, the confluent monolayer of EP cells maintained on HR-9-BM shows hemicyst formation, suggesting that they were capable of vectorial fluid transport. They also built a complex three-dimensional kidney tubulelike network. Some tubules became grossly visible and floated into the tissue culture medium, remaining tethered to the cell monolayer at either end of the tubule. On an ultrastructural level, the tubules consisted of cells held together with junctional complexes arranged so as to form a lumen. The smallest lumen were bordered by 2-3 cells, and the largest ones by 8-15 cells. The lumens of the larger tubules did contain granular fibrillar and amorphous debris. Low-density EP cell cultures maintained on HR-9-BM could be induced to proliferate at a rate approaching that of cultures exposed to serum when they were exposed to medium supplemented with high-density lipoprotein (HDL, 750 micrograms protein/ml) and transferrin (50 micrograms/ml). When exposed to HDL concentrations equal or lower than 250 micrograms protein/ml, low-density cultures proliferated at a slow rate and readily formed tubulelike structures. This observation indicates that EP cells do not need to reach confluence to undergo morphogenesis, and that HDL, which in the presence of transferrin supports the cell proliferation, can favor their differentiation into tubulelike structures once its concentration becomes limiting for mitogenesis.

Comparative Ultrastructure of Arthropod Transporting Epithelia

Abstract: The general organization of arthropod epithelia is compared to that of vertebrates. It is suggested that although ciliated epithelia, stratified epithelia and in some cases continuous muscle sheaths do not occur in arthropods, they have certain analogous structures which carry out the same functions. For example, the arthropod cuticle is compared to the squamous layer of vertebrate stratified epithelia, and complex arthropod basement membranes are compared to the muscle and connective tissue sheaths of certain vertebrate epithelia. The cellular organization of transporting epithelial cells is then discussed, with particular reference to elaboration of plasma membranes, and similarities and differences between vertebrates and arthropods, and between insects and crustaceans are pointed out. Specializations peculiar to insect cells are described, including the insertion of mitochondria into apical membrane microvilli, and the presence along this membrane of small particles called portasomes believed to be involved in active transport. Finally, it is shown that in the midgut of theinsect Manduca sexta , distinct ultrastructural changes accompany loss of potassium transport activity during a larval molt and in the prepupal stage. The ultrastructural changes which occur include a proliferation of the basement membrane and muscle tissue underlying the epithelium, and a change in the morphology of the potassium transporting goblet cells. Possible correlations between ultrastructural changes and loss of transport activity are discussed.

Mechanical trauma to bladder epithelium liberates prostanoids which modulate neurotransmission in rabbit detrusor muscle.

Abstract: Transitional epithelium of the rabbit urinary bladder has been implicated as a major site of prostanoid production and various studies have indicated that prostanoids have significant influences in muscle activity and neurotransmission in the bladder. We have examined the possibility that mechanical irritation of the epithelium could release diffusable substances which could influence neuromuscular function in the bladder. Epithelium was dissected from muscle strips of rabbit urinary bladder and the two components were incubated in separate chambers. Krebs' solution bathing epithelium was transferred to the bath in which the muscle was being field stimulated. Increases in the basal tension and spontaneous activity of the muscle as well as in the electrically evoked responses were observed after transfer and were related to the intensity of the irritation given the epithelium sample. The effects were mimicked by prostaglandins E1 E2, F2 alpha and I2 and the transfer effect was reduced significantly by pretreatment of the epithelium, but not the muscle, with indomethacin (10 microM) or ibuprofen (100 microM). Transfer of solution bathing-irritated epithelium also raised basal tension but not the maximum response to bethanechol. Finally, radioimmunoassay was used to demonstrate that irritation of epithelium samples caused the appearance of prostaglandin and 6-oxo-prostaglandin F1 alpha in the bathing medium and that this appearance was profoundly depressed by indomethacin (10 microM). It is plausible, therefore, that mechanical irritation of the bladder epithelium could result in changes in neuromuscular function in the underlying muscle layers and that these changes would be consistent with the symptoms associated with mechanical trauma of urothelium.

The thyroid microsomal antibody revisited. Its paradoxical binding in vivo to the apical surface of the follicular epithelium.

Abstract: We have shown that thyroid monolayers derived from the glands of patients with autoimmune thyroid disease have immunoglobulin (Ig) bound to their surface. This appears to have been deposited in vivo rather than during preparation of the monolayers, a view supported by our finding of such deposits on the apical margin of follicular cells in sections cut from these glands and stained with conjugated anti-immunoglobulin. It is likely that these deposits represent specific binding of so-called "microsomal" autoantibodies to the surface of the thyroid cells in vivo since staining of partially disrupted follicles ("half-melons") with Hashimoto serum containing microsomal autoantibodies in the indirect immunofluorescence (IFL) test, localized the antigen on the apical surface of the cells lining the follicular cavity. Thus, paradoxically, although the antigen is relatively inaccessible, autoantibodies do reach and combine with the thyroid surface in vivo and may therefore play a role in pathogenesis.

Immunocytochemical enhancement of basement membrane antigens by pepsin: applications in diagnostic pathology.

Abstract: Basement membrane zone antigens, laminin, Type IV collagen, and Type V collagen each are enhanced selectively in formalin-fixed, paraffin-embedded sections by pretreatment with pepsin (1 mg pepsin/mL 0.5 M acetic acid). Highly specific antibodies to laminin, Type IV collagen, and Type V collagen each demonstrate intense linear staining of epithelial and endothelial basement membranes in fresh tissue, but this staining is diminished markedly and often completely abolished in paraffin-embedded tissue. Pretreatment of this paraffin-embedded tissue with standard immunoperoxidase enhancement technics such as trypsin fails to increase immunoreactivity of these antigens. Pretreatment with other proteases with known collagenolytic activities such as bacterial collagenase and Type IV collagenase is likewise ineffective. In contrast, pepsin pretreatment markedly enhances immunoreactivity of laminin, Type IV collagen, and Type V collagen. Previous immunocytochemical studies of the basement membrane useful in the distinction of invasive tumors from their benign counterparts, for example, tubular carcinoma of the breast from sclerosing adenosis, which only could be done prospectively in fresh tissue now can be performed retrospectively in paraffin-embedded tissue.

Morphology of the exocrine glands of the frog skin.

Abstract: Frog skin contains three distinct types of exocrine glands: granular (poison), mucous, and seromucous. The granular gland forms a syncytial secretory compartment within the acinus, which is surrounded by smooth muscle cells. The mucous and seromucous glands are easily identifiable as distinct glands. The serous and mucous secretory cells are arranged in a semilunar configuration opposite the ductal end and are filled with granules. Within the acinus, located at the ductal pole of the gland, are distinct groups of cells with few or no granules in the cytoplasm. In both the mucous and seromucous gland there is a cell type with abundant mitochondria; the one in the mucous gland is located in the region adjacent to the secretory cells. The duct of these glands is two-layered, with the individual cells appearing morphologically similar to the layers of the skin epithelium as the duct traverses the skin. The duct appears to be patent throughout its length. The morphological heterogeneity and distinct distribution of the cell types within the gland acinus may be indicative of a functional heterogeneity that allows the production of distinctly different types of secretion from the same gland type, depending on the type of stimulus.

In vivo, cAMP stimulates growth and morphogenesis of mouse mammary ducts

Abstract: In culture, cAMP is known to be mitogenic for mammary cells and several other epithelia, but evidence for a similar role in vivo has been only correlative. We have used plastic implants to cause slow release of cholera toxin and other cAMP-active agents to local areas of mammary glands in ovariectomized mice. Elevated levels of intracellular cAMP around the implants promoted vigorous growth and normal ductal morphogenesis, while distant sites were unaffected. Local effects of cAMP included restoration of normal ductal caliber, formation of new end buds, and reinitiation of DNA synthesis in both epithelium and surrounding stroma. Thus, cAMP is both a mitogenic and a morphogenetic factor in this tissue.