Epidermal Epithelium Research Articles

Myringotomized mice develop myringosclerosis in the pars flaccida and not in the pars tensa.

The development of myringosclerosis has been correlated with increased production of oxygen-derived free radicals. For the present study, we used a null mutant mouse lacking extracellular superoxide dismutase to test the hypothesis that increased production of free radicals can cause the development of myringosclerosis. Null mutant mice and wild-type, control mice were myringotomized and kept in ambient air for 3 weeks. Both groups developed myringosclerosis in the pars flaccida, but not in the pars tensa. The sclerotic lesions were visible in both the light and the electron microscope but not in the otomicroscope. In particular, the localization of the sclerotic deposits was found beneath both the inner and outer epidermal epithelium. No difference concerning the extent or number of sclerotic lesions between the null mutant and the wild-type mice could be distinguished.

Coordinated morphogenesis of epithelia during development of the Caenorhabditis elegans uterine-vulval connection.

Development of the nematode egg-laying system requires the formation of a connection between the uterine lumen and the developing vulval lumen, thus allowing a passage for eggs and sperm. This relatively simple process serves as a model for certain aspects of organogenesis. Such a connection demands that cells in both tissues become specialized to participate in the connection, and that the specialized cells are brought in register. A single cell, the anchor cell, acts to induce and to organize specialization of the epidermal and uterine epithelia, and registrates these tissues. The inductions act via evolutionarily conserved intercellular signaling pathways. The anchor cell induces the vulva from ventral epithelial cells via the LIN-3 growth factor and LET-23 transmembrane tyrosine kinase. It then induces surrounding uterine intermediate precursors via the receptor LIN-12, a founding member of the Notch family of receptors. Both signaling pathways are used multiple times during development of Caenorhabditis elegans. The outcome of the signaling is context-dependent. Both inductions are reciprocated. After the anchor cell has induced the vulva, it stretches toward the induced vulval cells. After the anchor cell has induced specialized uterine intermediate precursor cells, it fuses with a subset of their progeny.

Expression of an Msx homeobox gene in ascidians: insights into the archetypal chordate expression pattern.

The Msx homeobox genes are expressed in complex patterns during vertebrate development in conjunction with inductive tissue interactions. As a means of understanding the archetypal role of Msx genes in chordates, we have isolated and characterized an Msx gene in ascidians, protochordates with a relatively simple body plan. The Mocu Msx-a and McMsx-a genes, isolated from the ascidians Molgula oculata and Molgula citrina, respectively, have homeodomains that place them in the msh-like subclass of Msx genes. Therefore, the Molgula Msx-a genes are most closely related to the msh genes previously identified in a number of invertebrates. Southern blot analysis suggests that there are one or two copies of the Msx-a gene in the Molgula genome. Northern blot and RNase protection analysis indicate that Msx-a transcripts are restricted to the developmental stages of the life cycle. In situ hybridization showed that Msx-a mRNA first appears just before gastrulation in the mesoderm (presumptive notochord and muscle) and ectoderm (neural plate) cells. Transcript levels decline in mesoderm cells after the completion of gastrulation, but are enhanced in the folding neural plate during neurulation. Later, Msx-a mRNA is also expressed in the posterior ectoderm and in a subset of the tail muscle cells. The ectoderm and mesoderm cells that express Msx-a are undergoing morphogenetic movements during gastrulation, neurulation, and tail formation. Msx-a expression ceases after these cells stop migrating. The ascidian M. citrina, in which adult tissues and organs begin to develop precociously in the larva, was used to study Msx-a expression during adult development. Msx-a transcripts are expressed in the heart primordium and the rudiments of the ampullae, epidermal protrusions with diverse functions in the juvenile. The heart and ampullae develop in regions where mesenchyme cells interact with endodermal or epidermal epithelia. A comparison of the expression patterns of the Molgula genes with those of their vertebrate congeners suggests that the archetypal roles of the Msx genes may be in morphogenetic movements during embryogenesis and in mesenchymal-epithelial interactions during organogenesis.

Expression ofsnail2,a Second Member of the Zebrafish Snail Family, in Cephalic Mesendoderm and Presumptive Neural Crest of Wild-Type andspadetailMutant Embryos

Transcripts of a newly discovered gene calledsnail2,encoding a zinc finger protein of the Snail family, first appear in rows of cephalic mesendodermal cells in gastrulating zebrafish embryos. At the end of gastrulation,snail2RNA accumulates in a domain of ectodermal cells that mark the border between the epidermal epithelium and the neural plate and includes precursors of the neural crest. During somitogenesis,snail2expression becomes restricted to neural crest.snail2is thus one of the earliest genes yet known to be specifically expressed in neural crest in zebrafish embryos. Sincesnail2is expressed in mesendoderm, a tissue layer whose convergence in the trunk is known to be altered in embryos homozygous for thespadetailmutation, we examinedsnail2expression inspadetailembryos. In these mutants, the number of cephalic mesendodermal cells expressingsnail2is strongly reduced and the distribution of cells containingsnail2andno tailtranscripts in the axial mesoderm is much broader than normal. Moreover, the embryos are shorter than normal at the end of gastrulation. This shows that, in addition to the failure of paraxial mesoderm to converge normally in the trunk during gastrulation,spadetailalso affects the elongation of the embryo and the convergence of axial and lateral mesendoderm in both trunk and head.

Physiologic and clinicopathologic effects of crude oil on loggerhead sea turtles

The physiologic and clinicopathologic effects of weathered South Louisiana crude oil exposure were studied in the laboratory in juvenile loggerhead sea turtles. Sea turtles ingested oil incidentally, and oil was observed clinging to the nares, eyes, and upper esophagus, and was found in the feces. Oiled turtles had up to a four-fold increase in white blood cell counts, a 50% reduction in red blood cell counts, and red blood cell polychromasia. Most serum blood chemistries (e.g., BUN, protein) were within normal ranges, although glucose returned more slowly to baseline values than in the controls. Gross and histologic changes were present in the skin and mucosal surfaces of oiled turtles, including acute inflammatory cell infiltrates, dysplasia of epidermal epithelium, and a loss of cellular architectural organization of hte skin layers. The cellular changes in the epidermis are of particular concern because they may increase susceptibility to infection. Although many of the observed physiological insults resolved with a 21-day recovery period, the long-term biological effects of oil on sea turtles remain completely unknown.

Epidermal ultrastructure of the adult parasitic phase female and encapsulated larva of Kronborgia isopodicola (Platyhelminthes, Fecampiidae): Phylogenetic implications

The parasitic phase female K. isopodicola possesses a ciliated epidermis of polyhedral cells. Adjacent lateral plasma membranes are separated at intervals creating intercellular spaces. Epidermal cilia are anchored by a horizontal rootlet, opposite which a spur projects from the basal body, and a narrow vertical rootlet. The cytoplasm contains coated vesicles, and coated pits lie between microvilli. Large granular and vesicular bodies (rhabdoids) are scattered through the epidermal epithelium; in the epidermis of the encapsulated larva, granular rhabdoids are densely packed and slender, more compact bodies also occur. The compact, granular and vesicular bodies are probably morphological variants of the same epidermal structures, suggested to undergo sequential changes accomplished in later stages by lysosomal activity. Morphologically similar epidermal bodies are found in triclads. They are also characteristic of the parasitic genus Urastoma, which shares other ultrastructural features with K. isopodicola. The Neodermata may have arisen from parasitic turbellarian forms, at a more “primitive” level of organization than ancestors of the contemporary Rhabdocoela.

An insect epidermal cell line (UMBGE-4): Structural and electrophysiological characterization

1. 1. The cellular organization (including junctional connectivity) and electrophysiological characteristics of the UMBGE-4 epithelial cell line originally derived from the cockroach were studied. These cells grew in culture in the form of hollow vesicles which could reach 5 mm in diameter. The wall of the vesicles varied in form and thickness from resembling a squamous to a columnar epithelium. Parts of the vesicle wall were multi-cellular with some cytoplasmic variability in the constituent cells. On the whole, the cellular architecture of the vesicles resembled that of a secretary epithelium with abundant microvilli and apical vacuoles, an extensive network of endoplasmic reticulum and prominent Golgi apparatus. 2. 2. The main type of cell junction was septate-like and comprised extensive, convoluted regions of cellular apposition with some gap junctions therein. The septate junctions were permeated extensively by lanthanum and the epithelium appeared to be leaky. 3. 3. A small negative trans-cellular (lumen) potential (mean value, −2.7 mV) was present and this was only transiently affected by changes in extracelluar Na +, K + or Cl − concentrations. 4. 4. The cells' resting membrane potentials were distributed normally around a mean of − 77 mV. Some 64% of resting membrane electrogenesis could be accounted for in terms of K + and Cl − permeabilities; Na + had no involvement. 5. 5. The structural, electrophysiological and biochemical characteristics taken together would suggest that the UMBGE-4 cells could serve as a useful model for the epidermal epithelium in insects.

Multicentric Squamous Cell Carcinoma in situ Resembling Bowen's Disease in Cats

Multicentric squamous cell carcinoma in situ was studied in 12 cats (eight castrated males and four spayed females). The neoplasms occurred in middle-aged to old (mean age = 12 years) mixed-breed cats with a variety of hair-coat colors. The lesions were found in haired pigmented regions of the skin, including the trunk, limbs, feet, head, and neck, and were unrelated to exposure to sunlight. Lesions occurred at multiple sites in nine cats and at solitary sites in three cats and were from 0.5 cm to 3.0 cm in diameter, irregular, slightly elevated, plaque-like or papillated, and partially alopecic. Histologically, the lesions consisted of sharply demarcated regions of neoplastic, keratinocytic infiltration of the epidermal and follicular infundibular epithelium. Neoplastic cells were confined to the epithelium without frank invasion of the dermis. Two histologic subclasses of multicentric squamous cell carcinoma in situ were identified, the irregular nonhyperkeratotic type and the verrucous hyperkeratotic type. Three cats also had invasive squamous cell carcinoma adjacent to lesions characteristic of multicentric squamous cell carcinoma in situ. Grossly, these were solitary 2.0-4.0 cm-diameter firm, crusted, crateriform cutaneous masses. During follow-up periods of 4 to 20 months (mean follow-up period = 11 months), neoplasms did not recur locally after surgical excision; however, similar lesions developed at new sites in four cats.(ABSTRACT TRUNCATED AT 250 WORDS)

Selection is not required to produce invariant T-cell receptor gamma-gene junctional sequences.

Recombination of V-, D- and J-gene segments can generate an enormous diversity of T-cell antigen receptor (TCR) gene sequences. Although many gamma delta T cells fully exploit this diversification process, those in the epidermal and vaginal epithelium do not, predominantly expressing invariant gamma delta receptors in which the V-(D)-J junctional sequences in almost all the productive rearrangements are identical. The almost exclusive use of identical TCRs by cells in these sites is thought to reflect recognition of a stress-induced autologous antigen. To explain the prevalence of the invariant junctional sequences, it has been proposed that thymic selection operates on a population of originally diverse progenitor cells, resulting in a homogeneous repertoire. Alternatively the invariant sequences may result from biases in the recombination machinery in the fetal thymic progenitors of these cells. We report here the use of mice into which mutated TCR gamma-gene rearrangement substrates have been introduced as transgenes to demonstrate directly that the canonical TCR V gamma 3-J gamma 1 and V gamma 4-J gamma 1 sequences occur at high frequency in the absence of the possibility of selection for the protein products.

Suprabasal marker proteins distinguishing keratinizing squamous epithelia: Cytokeratin 2 polypeptides of oral masticatory epithelium and epidermis are different

Abstract Terminal differentiation of squamous epithelia is usually characterized by the synthesis of a subset of cytokeratins (CKs) in suprabasal cell layers which become major components of the intermediate filament (IF) bundle cytoskeleton of the maturing cells. We have examined the significance, molecular nature and pattern of synthesis of the elusive human CK 2 by analyzing mRNAs from certain stratified epithelia, using in vitro translation, cDNA cloning, Northern blotting and in situ hybridization. We show that genuine polypeptides with the typical gel electrophoretic mobility of CK 2 exist but that the CK 2 present in the masticatory epithelia of hard palate and gingiva (CK 2p) differs from that found in epidermis (CK 2e) by its amino acid sequence and is encoded by a different gene. The two CKs 2 show only limited sequence homology (71% identical amino acid positions in the rod domain), and the oral CK 2p is more closely related to the corneal CK 3 (86%), as is also indicated by the cross-reaction of monoclonal antibody AE5. By in situ hybridization and immunocytochemistry, we further show that both CK 2e and CK 2p are expressed only in suprabasal cell layers of the specific epithelia where they can accumulate to represent major cytoskeletal proteins. We discuss this tissue-type specificity of CK 2 synthesis in otherwise morphologically and biochemically similar epithelia in relation to differences of IF appearance and packing in upper strata between epidermal and masticatory epithelia as well as to tissue formation and differentiation during development.

α-Enolase is restricted to basal cells of stratified squamous epithelium

We have developed a monoclonal antibody against a 50-kDa protein that binds preferentially to basal cells in the limbus of rat, rabbit, and human corneas (J. D. Zieske, G. Bukusoglu, and M. A. Yankauckas, Invest. Ophthalmol. Visual Sci. 33, 143–152, 1992). Here we we report on the purification and identification of the antigen. The 50-kDa antigen was purified from rabbit limbal and corneal epithelium using HPLC methodology including anion exchange (DEAE) followed by reverse-phase (C18) chromatography. The purified 50-kDa protein was then digested with endoproteinase Lys-C, and a reproducible profile comprising approximately 20 peptides was observed by reverse-phase HPLC of the digest. Sequence analysis of five peptides ranging in length from 4 to 20 residues revealed that the 50-kDa protein was α-enolase, a glycolytic enzyme. Overall, 57 amino acids were identified with a 95% sequence homology. Localization of α-enolase in rat epithelium by immunofluorescence microscopy demonstrated that simple epithelium contained low or undetectable levels of the enzyme. Stratified squamous epithelium, however, showed high levels of α-enolase, which was localized specifically to cells of the basal layer. Epidermal, corneal limbal, oral mucosal, vaginal, and laryngeal epithelium all showed cytoplasmic binding specific to the basal cells. These data indicate that the glycolytic enzyme α-enolase is preferentially localized in the basal cell layer of stratified squamous epithelium and suggest that glycolytic activity is concentrated in these cells. The localization pattern suggests that a major change in metabolism occurs as cells leave the mitotically active basal cell layer and migrate toward terminal differentiation in the suprabasal cell layers.

Epidermal Inclusions in Abdominal Lymph Nodes

Abdominal lymph nodes from men aged 48 and 62 years with gastric adenocarcinoma were examined histologically. A few of the lymph nodes contained epidermal epithelium, although there was no metastasis. Scattered squamous epithelial nests and epidermal cysts were found within the lymph nodes, and small amounts of pancreatic tissue were present adjacent to the epidermal inclusions. Some squamous cell nests showed cyst formation, and some others showed squamous cell nests together with mucin-containing cells forming luminal structures. Immunohistochemically, the squamous cell nests stained weakly for CA19-9 but were negative for CEA or CA125. These lesions were considered to be similar to lymphoepithelial cysts of the pancreas.

Cytochrome P4501A induction in tissues, including olfactory epithelium, of topminnows (Poeciliopsis spp.) by waterborne benzo[a]pyrene.

Topminnows of the genus Poeciliopsis are susceptible to hepatocarcinogenesis by waterborne exposure to procarcinogenic polycyclic aromatic hydrocarbons (PAH). We examined induction of cytochrome P4501A (CYP1A) in liver and other organs of the species P. monacha and P. lucida exposed to benzo[a]pyrene (B[a]P) in water (added in acetone carrier) at 1 mg/l for 48 and 90 h. Fish were fixed whole in formalin, and CYP1A was examined immunohistochemically in sagittal sections of whole animals by staining with monoclonal antibody 1-12-3, which recognizes a single cross-reacting CYP1A protein in Poeciliopsis liver microsomes. Fish exposed to B[a]P for 48 h showed moderate staining, and those exposed for 90 h showed strong specific staining in various epithelial cells in both species. These included hepatocytes, pancreatic cells, epithelial cells in gill, enterocytes of the gut, and kidney tubular epithelium. Endothelial cells in several organs, including gill pillar cells and endocardial cells in the heart, showed strong staining. Staining was stronger in P. monacha than in P. lucida. Untreated animals of both species showed mild staining of the same cells stained in B[a]P-treated fish. In P. monacha, carrier (acetone) elicited a moderate increase in staining in most cell types, including those of liver and gill; the basis for this acetone effect is not known. There was a very strong specific induction by B[a]P in olfactory epithelium and epidermal taste bud epithelium of P. monacha, the first demonstration of strong CYP1A induction in chemosensory epithelia exposed to inducer in a physiologically relevant way. This study clearly establishes that waterborne PAH can elicit induction of P4501A proteins in multiple cell types in many organs of fish, with some sites of induction (olfactory epithelium) possibly related directly to the route of exposure. The species differences in the induction response, with induction in liver and some other organs generally being greater in P. monacha than in P. lucida, could be related to previously recognized species differences in PAH toxicities in Poeciliopsis.

Variable expression of retinoie acid receptor (RARβ) mRNA in human oral and epidermal keratinocytes; relation to keratin 19 expression and keratinization potential

Abstract Previous studies have revealed that the cells that form the different regions of the oral and epidermal stratified squamous epithelia represent a number of intrinsically distinct keratinocyte subtypes, each of which is developmentally programmed to preferentially express a particular pattern of keratins and type of suprabasal histology. Retinoic acid (RA) is known to modulate stratified squamous epithelial differentiation, including expression of the basal cell keratin K19 and the suprabasal keratins K1/K10 and K4/K13. We have found that all keratinocyte subtypes are similar in their steady state levels of RARα and RARγ mRNAs in culture and that these levels are only minimally affected by RA. In contrast, RARβ mRNA expression varies greatly among keratinocyte subtypes and, in eight of ten cell strains examined, directly correlated with their levels of K19 mRNA. Exposure to 10 -6 M RA increases the levels of RARβ and K19 mRNA; conversely, complete removal of RA from the medium results in reduced levels of these messages. RA does not coordinately induce RARβ and K19 messages in nonkeratinocyte cell types: fibroblasts cultured in the presence of 10 -6 M RA express very high levels of RARβ mRNA but do not express detectable K19, and mesothelial cells decrease their levels of RARβ and K19 mRNA in response to 10 -6 M RA. The correlation between RARβ and K19 mRNA levels in most keratinocyte subtypes suggests a role for RARβ in specifying patterns of keratin expression and suprabasal differentiation in stratified squamous epithelia.

Phenotypic analysis and gamma delta-T cell receptor repertoire of murine T cells associated with the vaginal epithelium.

T cells expressing alpha beta- and gamma delta-TCR are associated with the murine vaginal epithelium. A combination of phenotypic analysis of cell surface Ag and molecular analysis of the gamma- and delta-genes was used to demonstrate that vaginal gamma delta-T cells have several features that distinguish them from gamma delta-T cells present in other tissues. Three color flow cytofluorometric analysis demonstrated that freshly isolated vaginal gamma delta-T cells are CD4-CD8- and their expression of Thy-1 is strain dependent. Furthermore, specific differences in CD5, CD28, and p55IL-2 receptor expression were found between alpha beta- and gamma delta-T cells isolated from vaginal tissue. The vaginal gamma delta-T cells are predominantly CD45+, pgp-1+, HSA-, Ly-6C-, and MEL-14-. Both alpha beta- and gamma delta-T cells were absent in vaginal tissue from nude mice, although Thy-1-positive cells are present. It was also demonstrated that V gamma 4 and V delta 1 are the only gamma- and delta-genes that are expressed by vaginal cells. Sequence analysis of their junctions revealed that they express the V gamma 4 and V delta 1 sequences also found in fetal thymocytes. Furthermore, the V delta 1 sequence is identical in the vaginal cells and the gamma delta-T cells from the epidermal epithelium. We conclude that the vagina, like the skin, is a site where gamma delta-T cells with an invariant TCR exist.

Epithelial heterogeneity in the murine thymus: a cell surface glycoprotein expressed by subcapsular and medullary epithelium.

A monoclonal antibody (MAb), G8.8, was raised against glycoconjugates isolated from a cloned line of murine medullary thymic epithelial cells. Flow cytometric analysis of the reactivity of this MAb with cultured thymic epithelium demonstrated that the ligand was expressed on the cell surface. Immunohistochemical examination of normal murine thymus revealed labeling of cells in the subcapsular and medullary areas. Immunoelectron microscopy revealed surface labeling restricted to cells possessing ultrastructural features of epithelium (desmosomes, tonofilaments, and cytoplasmic cysts). During thymic ontogeny, G8.8+ cells predominated in fetal development at the earliest time point examined (Day 14 of gestation). There was an expansion of the cortical epithelial component so that by Day 18 cortical and medullary compartments could be clearly distinguished. Immunoprecipitation of radioiodinated thymic stroma with MAb G8.8 detected a molecule with an apparent Mr of approximately 38 KD under non-reducing conditions. When reduced, the apparent Mr was slightly increased (42 KD). This MAb also exhibited reactivity with gut and epidermal epithelium and some tubular epithelium in the kidney, but did not react with epithelial parenchymal cells of the liver.

Epidermal and urethroid penile cyst.

The authors describe a 74-year-old man who presented with a 2-cm nodule on the ventral face of the penis, showing histologically a cyst lined by both epidermal and urethroid epithelium. The authors discuss the various histological forms of raphe median cysts of the penis.

Ecdysone-dependent proteolysis of an apical surface glycoprotein may play a role in imaginal disc morphogenesis in Drosophila

An apical surface glycoprotein, designated gp125 for its apparent molecular weight of 125,000, appears in Ca2(+)-free, ionic detergent extracts of imaginal discs of Drosophila melanogaster in response to the steroid hormone, 20-hydroxyecdysone (20-HE). Gp125 is not synthesized in response to 20-HE, but results from modification of an existing macromolecule. Treatment of discs or larval epidermis with serine protease (e.g., trypsin) results in hormone-independent production of gp125. Antiserum raised to electrophoretically purified gp125 recognizes, in addition to gp125, two closely related glycoproteins with higher apparent molecular weights, gp200 and gp180. This family of glycoproteins is localized at the apical surface of imaginal disc cells and of the epidermal epithelium in embryos, larvae and prepupae. Ca2+ affects both the solubility and the proteolytic products of this family of glycoproteins. We discuss the possibility that gp125 is generated through the action of a hormonally controlled serine protease in a process that is necessary for disc morphogenesis.

Light Microscopy

The histological course of reaction in borderline leprosy has been described by Ridley and Radia. They are dermal edema, dilatation of the lymphatics, swelling of the granulomas, changes in the concentration and distribution of lymphocytes and giant cells, maturity of the histiocytes, and presence of neutrophils. New markers for the condition are spongiosis of the epidermal and follicular epithelium with exocytosis of mononuclear cells, parakeratosis, focal interface changes with occasional individual cell necrosis of keratinocytes, and lastly, follicular mucinosis. Recognition of this reaction is vital in the prevention of deformities secondary to nerve damage.

Distinct antigen receptor repertoires of two classes of murine epithelium-associated T cells

T lymphocytes are found not only as recirculating cells in the lymphoid system, but also as immobile cells in certain epithelia. T-cell antigen receptors (TCR) of both alpha/beta and gamma/delta-heterodimer subtypes can exhibit an extremely high degree of diversity. The diversity of alpha/beta TCRs derives from the use of a large number of variable (V) gene segments, as well as junctional diversity generated during rearrangement of these segments, whereas the diversity of gamma/delta TCRs derives largely from junctional elements, with a smaller contribution from a limited number of V gene segments. Many T cells in the epidermal and intestinal epithelia of mice express TCR composed of gamma/delta heterodimers. We demonstrate here that gamma/delta TCRs of T cells in both these tissues are restricted in V gene usage, with different elements predominating. The TCR junctional diversity of epidermal T cells, however, is extremely limited, whereas that of intestinal T cells is extremely diverse. The distinctive features of these two populations suggest that they develop or are selected differently for particular tissue-specific functions.