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Results for “epithelial maturation”

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At least 73 records · Page 4Linked to original sources
PubMed1991

Binding sites for P and/or type 1-piliated Escherichia coli in human ureter.

Adherence sites for uropathogenic Escherichia coli in the excised human ureter were studied by using scanning electron microscopy. P-piliated E. coli adhered to younger epithelial cells which had microvilli on their surfaces, but did not to mature epithelial cells which had microfolds on their surfaces. This adherence was D-mannose resistant and alpha-D-Galactopyranosyl-(1----4)- beta-D-Galactopyranoside sensitive. Type-1 piliated E. coli adhered to both types of epithelial cells, but it was prevented by D-mannose. Entrapment of adherent type 1-piliated E. coli was observed only on the epithelial cells with microfolds. This model system allowed quantitative estimates of bacterial adherence to the luminal surface of the human ureteral mucosa in vitro, and demonstrated different manners of adherence of P and type 1-piliated E. coli.

Bacterial Adhesion↗
PubMed1985

Malignant transformation in human colorectal mucosa as monitored by distribution of laminin, a basement membrane glycoprotein.

The distribution of laminin, a basement membrane glycoprotein, was studied by indirect immunofluorescence technique using rabbit anti-laminin serum in fifty-seven samples of normal, hyperplastic, adenomatous and carcinomatous colorectal tissue. As judged by the expression of laminin normal, hyperplastic and adenomatous colorectal mucosa were characterized by a continuous, linear basement membrane. A thick band-like basement membrane was seen under the surface epithelium and at the mouths of the crypts in normal and hyperplastic mucosa. The adenomatous epithelium was uniformly characterized by a thin, linear basement membrane. In contrast, marked alterations were constantly observed in colorectal carcinomas and their metastases, which showed a discontinuous, linear or patchy basement membrane. Our study suggests that the expression of laminin is related to cellular differentiation, and the thickness of the laminin-positive basement membrane parallels with the epithelial maturation of normal and hyperplastic colorectal mucosa and with the failure of the epithelial differentiation in adenomas. In colorectal carcinomas and their metastases the distribution of laminin is constantly altered and the severity of the alterations correlates with the histological grade of these tumours.

Adenocarcinoma↗
PubMed1997

[Stem cell-fed maturational lineages and epithelial organogenesis].

Stem cell-fed maturational lineages have long known to exist in rapidly proliferating tissues such as bone marrow, gut and epidermis. Recent studies support the hypothesis that stem cell-fed maturational lineages occur also in quiescent tissues. In this review is presented evidence for this hypothesis using liver as one of the model systems representative of quiescent tissues. In addition, studies are summarized indicating that control of growth and tissue-specific gene expression is dependent on maturational lineage mechanisms operating dynamically and sometimes synergistically in combination with gradients of regulatory signals that include hormones, growth factors and extracellular matrix components. Tissue engineering for optimal maintenance of cells and tissues ex vivo and for the development of bioartificial organs will depend on use of cells at specific maturational lineage stages, seeding them onto substrata of specific mixtures of extracellular matrix components, and culturing them in hormonally and nutritionally defined media.

Cell Differentiation↗
PubMed2005

Androgen receptor expression helps to differentiate basal cell carcinoma from benign trichoblastic tumors.

Histologic differentiation between basal cell carcinoma and benign trichoblastic neoplasms such as trichoepithelioma and trichoblastoma can be difficult on small biopsies. Therefore, several attempts have been made to identify immunohistochemical differences between these entities. Recent studies have shown androgen receptor expression in a number of mature epithelial structures in the skin and in epithelial neoplasms including basal cell carcinoma. In contrast, androgen receptor expression was absent in mature hair follicles or the few trichogenic neoplasms studied to date. These findings suggested that androgen receptor expression might be a useful adjunct in the histologic differential diagnosis between basal cell carcinoma and benign trichoblastic neoplasms. Therefore, we performed immunohistochemical analysis of androgen receptor expression in 32 basal cell carcinomas and 10 benign trichoblastic tumors (6 trichoepitheliomas and 4 trichoblastomas). In our study, at least focal expression of androgen receptor was detected in 78% of basal cell carcinomas. None of the trichoblastic tumors showed any androgen receptor immunoreactivity. These results confirm the lack of expression of androgen receptor in benign trichoblastic neoplasms and indicate that androgen receptor expression by tumor cells points to basal cell carcinoma as the most likely diagnosis.

Adult↗
PubMed2004

Studies on the differentiation pathway and growth characteristics of epithelial culture cells of the human prostate.

We established explant primary cultures in order to study the growth and hormone responsiveness, and the differentiation process of prostatic epithelial cells. Cell outgrowth was achieved from explant tissue by using a new DU145-cell-conditioned medium and special plastic coverslips. To define the present model, proliferation assays were tested by [3H]thymidine assay and planimetric analysis. Cells were analyzed using immunocytochemistry, light, phase contrast and electron microscopy, polymerase chain reaction, telomerase ELISA and immunoassay (PSA). Morphology and electron microscopy revealed typical epithelial differentiation. Immunocytochemistry showed the content of basal and secretory epithelial cells, endocrine paracrine cells and a high level of proliferation. With increasing culture time, mature epithelial differentiation (PSA) increases and the initial increase of alpha-smooth muscle actin (alpha-SMA) decreases again. After further passaging, alpha-SMA expression is no longer detected and PSA expression decreases. Furthermore, epithelial cells showed both androgen responsiveness and androgen receptor expression. These findings show the presence of epithelial cells in a process of differentiation with endocrine paracrine cells and a high level of proliferation. This model may maintain the cellular and functional properties more closely related to the human prostate and may provide a valuable tool for studying stem cells and differentiation characteristics.

Cell Culture Techniques↗
PubMed1985

Refractive keratoplasty. Histopathology of clinical specimens.

Two keratophakia (KF), one epikeratophakia (EKP), three myopic keratomileusis (MKM), and three hypermetropic keratomileusis (HKM) specimens obtained 3.5 to 31 months following refractive keratoplasty were evaluated. The corneas were removed at keratoplasty due to postoperative complications, such as corneal edema, irregular astigmatism, delayed reepithelialization, stromal ulceration, epithelial interface ingrowth, and loss of visual acuity. The KF specimens demonstrated viable epithelium in the recipient-donor lenticule interface, disruption of the normal collagen lamellar pattern in the lenticule, and absence of keratocytes. All of the keratomileusis lenticules and the one epikeratophakia lenticule had variable keratocyte repopulation. All specimens showed irregular epithelial maturation. In one case of myopic keratomileusis, ferritin-like particles were found in the epithelial intercellular spaces. Folds in Bowman's membrane were seen in several keratomileusis lenticules; in one case, breaks in Bowman's membrane (BM) were seen.

Adult↗
PubMed1988

Cigarette smoking and other correlates of cytologic estrogen effect in postmenopausal women.

Cigarette smoking and other factors associated with estrogen-related diseases may influence risk through hormonal mechanisms. To investigate the sex hormone associations of these risk factors, vaginal scrape cytology specimens and questionnaire data were obtained on 215 postmenopausal women at the time of routine pelvic examination. All specimens were read blindly by one cytologist, and the relationships between the indices of maturation and risk factors were assessed with regression techniques. Current cigarette smoking and obesity were associated with increased maturation. In contrast, years past menopause, parity, and coffee and tea consumption were all unrelated to vaginal epithelial maturation. These results elucidate the mechanisms underlying the antiestrogenic effect of cigarette smoking and support the concept that obesity is associated with an estrogenic effect.

Aged↗
PubMed1986

Intraepithelial neoplasia of the larynx. A clinicopathologic study of six cases with DNA analysis.

For six patients with partial or total laryngectomies with extensive mucosal hyperplasias, we generated DNA histograms from multiple mucosal sites using Feulgen-stained tissue sections and microspectrophotometric microscopy. Aneuploid DNA histograms were identified in the mucosa of all six specimens, indicating that neoplastic transformation had occurred. The histologic characteristics of neoplastic change included thickened or hyperplastic epithelium, surface maturation or keratinization, often a proliferation of small, immature basallike cells in the depths of the epithelium, and evidence of abnormal epithelial maturation as evidenced by focal areas of cytoplasmic keratinization in the lower portions of the mucosa. We think this histologic expression of intraepithelial neoplasia is more common than the "classic" form of carcinoma in situ with full mucosal replacement by proliferating immature basallike cells. Keratin is a common reaction in laryngeal mucosa, and its presence on the surface or in the depths of the epithelium does not militate against the diagnosis of severe intraepithelial neoplastic transformation.

Aged↗
PubMed1994

Characterization of human papillomavirus type 16 activity in separate biopsies from a carcinoma of the cervix uteri.

Human papillomavirus (HPV) 16-specific nucleic acid sequences were analysed in separate biopsies taken from a patient with a poorly differentiated squamous cell carcinoma of the uterine cervix. Biopsies were obtained from histopathologically normal epithelium adjacent to the carcinomatous epithelium, the primary carcinoma and a metastatic lymph node. Signals characterizing viral DNA and oncogene transcription were obviously differentiation dependent as shown by in situ hybridization of viral nucleic acids and immunofluorescence of epithelial differentiation specific proteins. In histologically normal parts of the epithelium viral DNA was amplified at the transition from basal to maturing cells, whereas E6/E7 genes were actively transcribed mainly in maturing epithelial cells following the basal cell layer. Some of the cells in the primary carcinoma and in the metastatic lymph node expressed involucrin at increased levels. Signals for viral DNA and HPV 16-specific E6/E7 transcripts decreased in intensity during differentiation in an inverse relationship to the observed involucrin increase in those cells. The absence of Ki67 in cells expressing large amounts of involucrin as revealed by immunostaining, support the inverse correlation between differentiation of cancer cells, HPV 16 replication and E6/E7 transcription. The changes in cytokine expression may indicate an HPV 16 associated disruption of normal cytokine expression pattern in the carcinoma.

Biopsy↗
PubMed1979

Translocation of dimeric IgA through neoplastic colon cells in vitro.

We studied the translocation of dimeric IgA across epithelium, using neoplastic human colon cells in culture as a source of epithelial cells, and immunoelectronmicroscopy with peroxidase-labeled antigens and antibodies. The cells had some of the ultrastructural characteristics of normal, mature epithelial cells, i.e., polarity, desmosomal junctions, and secretory component on their basal and lateral plasma membranes. Horseradish peroxidase-labeled dimeric IgA, exposed to the cells at 0 degrees C, bound selectively to secretory component on the cell surfaces. At 37 degrees C, the bound dimeric IgA was taken into the cells by endocytosis and transported apically through the cytoplasm in vesicles. After 30 min, IgA was discharged across the apical surface. Neither colchicine (10(-4) M) nor cytochalasin B (10(-5) M) interfered with binding or endocytosis of dimeric IgA, but colchicine inhibited intracellular transport of the IgA-containing vesicles. These experiments demonstrated that dimeric IgA can be transported through living intestinal epithelial cells in vitro. The transport includes 1) specific binding of IgA dimers to secretory component on plasma membranes, 2) endocytosis of IgA in vesicles, 3) transcytoplasmic transport of the IgA-containing vesicles by a process involving microtubules, and 4) discharge of IgA at the apical surfaces.

Binding Sites, Antibody↗
PubMed2000

An essential role for thymic mesenchyme in early T cell development.

We show that the mesenchymal cells that surround the 12-d mouse embryo thymus are necessary for T cell differentiation. Thus, epithelial lobes with attached mesenchyme generate all T cell populations in vitro, whereas lobes from which mesenchyme has been removed show poor lymphopoiesis with few cells progressing beyond the CD4(-)CD8(-) stage of development. Interestingly, thymic mesenchyme is derived from neural crest cells, and extirpation of the region of the neural crest involved results in impaired thymic development and craniofacial abnormalities similar to the group of clinical defects found in the DiGeorge syndrome. Previous studies have suggested an inductive effect of mesenchyme on thymic epithelial morphogenesis. However, we have found that mesenchyme-derived fibroblasts are still required for early T cell development in the presence of mature epithelial cells, and hence mesenchyme might have a direct role in lymphopoiesis. We provide an anatomical basis for the role of mesenchyme by showing that mesenchymal cells migrate into the epithelial thymus to establish a network of fibroblasts and associated extracellular matrix. We propose that the latter might be important for T cell development through integrin and/or cytokine interactions with immature thymocytes.

Animals↗
PubMed1977

C bodies and R bodies in the epithelial cells of normal and diseased human rectum.

Small spherical, extracellular bodies (C bodies) measuring 20 to 80 nm in diameter and enclosed by a trilaminar membrane 7 nm wide surrounded the microvilli of human rectal epithelial cells. Similar bodies were observed within membrane-bound vesicles (R bodies) in the apical cytoplasm. The C bodies associated with the mature epithelial cells of the luminal surface were more numerous than those associated with the immature cells of the crypts, where the R bodies predominated. A decreased number of C bodies was observed in ulcerative colitis. We concluded that the membrane-bound C bodies surrounding the microvilli were cellular in origin and arose from R bodies within the cytoplasm of the rectal epithelial cells.

Cell Membrane↗
PubMed1979

Human vaginal epithelial multilayer tissue culture.

Fragments of normal human adult vagina, when explanted onto glass slides gave rise to outgrowing sheets of pure epithelium, which had microscopic morphological features in common with normal vaginal epithelium. Infrequent fibroblast contamination was observed. Proliferating epithelial cells formed multilayers of stratified squamous epithelium and demonstrated a progressive decrease in proliferative activity after 14 days. Continuous lines of epithelial cells were not obtained. Even in the absence of estrogens, transmission electron microscopy revealed evidence of keratinization of the superficial cells of the multilayer. Scanning electron microscopy of the surface of mature epithelial cells in culture revealed ultrastructural features that closely resembled those present on the surface of exfoliated cells obtained by scraping the vagina in vivo. This in vitro tissue culture model of human vaginal epithelium may provide a simple method of studying factors that influence vaginal epithelium growth, maturation and function.

Cell Differentiation↗
PubMed2001

Temporally compartmentalized expression of ephrin-B2 during renal glomerular development.

Glomerular development proceeds through the spatially ordered and sequential recruitment, proliferation, assembly, and differentiation of endothelial, mesangial, and epithelial progenitors. The molecular determinants of cell-cell recognition and targeting in this process have yet to be defined. The Eph/ephrin family of membrane receptors and counter-receptors are critical participants of developmental vascular assembly in extrarenal sites. Renal expression patterns of ephrin-B2 and EphB4 were investigated using mice expressing beta-galactosidase under control of ephrin-B2 or EphB4 promoters. The earliest glomerular expression of ephrin-B2 was identified in a subset of differentiating comma-stage glomerular epithelial cells (podocyte progenitors) adjacent to the vascular cleft where endothelial progenitors are subsequently recruited. Epithelial ephrin-B2 expression was accompanied by expression in endothelial and mesangial cells as capillary assembly progressed. At or near completion of glomerular maturation, epithelial ephrin-B2 expression was extinguished, with persistence in glomerular endothelial cells. Throughout development, one of several ephrin-B2 receptors, EphB4, was persistently and exclusively expressed in endothelial cells of venous structures. The findings show sequential ephrin-B2 expression across glomerular lineages, first in a distinct subset of podocyte progenitors and subsequently in endothelial cells of the developing glomerulus. Given targeting functions for Eph/ephrin family proteins, the findings suggest that ephrin-B2 expression marks podocyte progenitors at the site of vascular cleft formation, where expression may establish an "address" to which endothelial and mesangial progenitors are recruited. Thus, the present results suggest that ephrin-B2 and EphB interactions play an important role in glomerular microvascular assembly.

Animals↗
PubMed2001

Expression of apoptosis-associated speck-like protein containing a caspase recruitment domain, a pyrin N-terminal homology domain-containing protein, in normal human tissues.

Apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) is a pyrin N-terminal homology domain (PYD)- and caspase recruitment domain (CARD)-containing a proapoptotic molecule. This molecule has also been identified as a target of methylation-induced silencing (TMS)-1. We cloned the ASC cDNA by immunoscreening using an anti-ASC monoclonal antibody. In this study, we determined the binding site of the anti-ASC monoclonal antibody on ASC and analyzed the expression of ASC in normal human tissues. ASC expression was observed in anterior horn cells of the spinal cord, trophoblasts of the placental villi, tubule epithelium of the kidney, seminiferous tubules and Leydig cells of the testis, hepatocytes and interlobular bile ducts of the liver, squamous epithelial cells of the tonsil and skin, hair follicle, sebaceous and eccrine glands of the skin, and peripheral blood leukocytes. In the colon, ASC was detected in mature epithelial cells facing the luminal side rather than immature cells located deeper in the crypts. These observations indicate that high levels of ASC are abundantly expressed in epithelial cells and leukocytes, which are involved in host defense against external pathogens and in well-differentiated cells, the proliferation of which is regulated.

Animals↗
PubMed1984

The biomaterial-tissue interface: a morphological study utilizing conventional and alternative ultrastructural modalities.

The interface between oral tissues and ceramic endosteal dental implants was investigated in 36 experimental cases in dog jaws. Conventional electron microscopic modalities showed those tissues adjacent to the implants to be viable with no adverse cellular response to the biomaterial. A procedure to retrieve additional ultrastructural data from previously processed biological material was developed to expand upon these data. This included surface-etching with oxygen plasma of routinely processed electron microscopy specimens and formalin fixed histological specimens for scanning electron microscopy (SEM) study; and, cryofracturing of similar histological specimens for additional transmission electron microscopic (TEM) analysis. Results from these alternative protocols supported our observations from conventional studies of the direct association of bone and epithelia to the implant. In addition, they demonstrated a unique portrayal of the epithelial maturation patterns. Further, this alternative TEM method showed excellent retention of cellular integrity and demonstrated a hemidesmosomal-external basal lamina attachment apparatus at the junctional epithelial-implant interface. This latter composite attachment structure was not retained in our previous conventional microdissection procedures. Thus, the interface between oral tissues and the single crystal sapphire endosteal dental implant could be elucidated by these protocols.

Animals↗
PubMed1996

Expression of laminin alpha 1, alpha 5 and beta 2 chains during embryogenesis of the kidney and vasculature.

Laminins, found predominantly in basement membranes, are large glycoproteins consisting of different subsets of alpha, beta and gamma chain subunits. To resolve conflicting data in the literature concerning coexpression of alpha 1 and beta 2 chains, expression of alpha 1 chain was studied with two different antisera against the E3 fragment of laminin alpha 1 chain. Expression of the alpha 1 chain was seen in several types of epithelial basement membranes throughout development, but its expression in rat glomerular basement membranes and some other types of epithelial basement membranes occurred only during early stages of development. By contrast, beta 2 chains were detected by immunofluorescence only during advanced stages of glomerulogenesis and vascular development. By Northern and Western blots, beta 2 chains were detected somewhat earlier, but in situ hybridization revealed that beta 2 chain was also confined to vasculature during the earlier stages. It thus seems that, in the tissues studied here, the expression of alpha 1 and beta 2 chains was mutually exclusive. To explore whether the newly described alpha 5 chain is expressed in locations lacking alpha 1 chain, expression of alpha 5 chain was studied by Northern blots and in situ hybridization. The alpha 5 chain was not uniformly expressed in all embryonic epithelial cell types but was present mainly in epithelial sheets which produce very little alpha 1 chain. There also appeared to be a developmental trend, with alpha 1 chain appearing early and alpha 5 later, in maturing epithelial sheets. The alpha 5 chain could be a major alpha chain of the adult glomerular basement membrane.

Aging↗
PubMed1978

Influence of restricted diet on epithelial renewal and maturation in the mice jejunum.

It has been known that the intestinal epithelial cell is characterized by a rapid cell turnover and by a gradient of differentiation from crypt to villus. The present study was undertaken to clarity the effect of diet on the migration and the maturation of the intestinal epithelial cells. The transit time from the crypt to the extrusion zone at the villus tip was determined with tritiated thymidine. To study the maturation of the cells the distribution of the terminal digestive enzymes, maltase [EC 3.2.1.20] and leucylnaphthylamidase E1EC 3.4.1.1], along the villus and crypt was analyzed quantitatively. And total activities of the same enzymes were assayed also in the mucosal homogenates. It was observed that the decrease in the migrating speed of villus cells was brought by energy restriction and the decrease in the migrating speed was associated with an increase of the enzyme activities in the upper zone of villus. And the result was that the intestinal epithelial cells which decrease in migrating speed by dietary restriction become more mature on the upper villus than those with unrestriced control.

Animals↗