Outer Epithelium Research Articles

Tricholemmal Carcinoma/Squamous Cell Carcinoma With Tricholemmal Differentiation

Abstract: Tricholemmal carcinoma is a low-grade cutaneous malignancy, which typically arises on the sun-exposed, hair-bearing areas of elderly male patients. Histologically, tricholemmal carcinoma is composed of a lobular proliferation of pale to clear squamoid cells with peripheral palisading. The tumors are typically centered on a pilosebaceous unit and demonstrate follicular and epidermal connections. The presence of cytologic atypia, frequent mitoses, and dermal invasion distinguishes tricholemmal carcinoma from tricholemmomas. Other clear cell tumors that may be considered in the differential diagnosis include clear cell Bowen's disease and squamous cell carcinoma (SCC), clear cell basal cell carcinoma, sebaceous carcinoma, clear cell hidradenoma, hidradenocarcinoma, and metastatic renal cell carcinoma. Tricholemmal carcinoma is typically considered a cutaneous adnexal tumor with differentiation towards the external root sheath epithelium. Although some authors have questioned the validity of this concept and asserted that tricholemmal carcinoma is merely a clear cell SCC, there are distinct histologic differences between tricholemmal carcinoma and clear cell SCC. These include the former's lobular growth pattern, centering on pilosebaceous units, peripheral palisading, and presence of PAS-positive glycogen accumulations, all of which are lacking in cases of clear cell squamous cell carcinomas. However, it may be argued that tricholemmal carcinoma is simply a unique type of clear cell SCC, which either arises from or recapitulates outer root sheath epithelium, explaining its distinct features. In either case, the excellent clinical prognosis of tricholemmal carcinoma argues that this entity should continue to be separated diagnostically from other clear cell tumors of the skin.

Roles of Na,K-ATPase in Early Development and Trophectoderm Differentiation

Before implantation into the uterine wall, the mammalian embryo undergoes a period of cell division, cell shape change, and cell differentiation leading to the formation of an outer epithelium, the trophectoderm. The trophectoderm is the part of the embryo that initiates uterine contact and, after transformation to become the trophoblast, uterine invasion. Similar to the kidney nephron, the trophectoderm is a transporting epithelium with distinct apical and basolateral membrane domains; its function is to facilitate transepithelial Na+ and fluid transport for blastocoel formation. That transport is driven by Na,K-adenosine triphosphatase (ATPase) localized in basolateral membranes of the trophectoderm. Preimplantation embryos express multiple alpha and beta subunit isoforms of Na,K-ATPase, potentially constituting multiple isozymes, but the basolaterally located alpha1beta1 isozyme appears to function uniquely to drive fluid transport. Embryos unable to express alpha1 subunits because of targeted deletion of the gene are able to form a blastocoel, but they fail to maintain their integrity and expire during the peri-implantation period. Preimplantation embryos also express the gamma subunit, a modulator of Na,K-ATPase activity, but targeted deletion of that gene did not reveal an essential developmental role. The preimplantation embryo offers a unique model for understanding the roles of Na,K-ATPase subunit isoforms in epithelial development and transepithelial transport.

Comparative studies on the corneal structural adaptation of two rodents inhabiting different environments

The corneas of Rattus rattus and Meriones shawi are composed of three main layers; an outer epithelium, a middle stroma (basement membrane, total stroma and Descemet’s membrane) and an inner endothelium. The mean thickness of the epithelium, total stroma, Descemet’s membrane, and endothelium was about 52 ± 7.3 μm, 275 ±18.7 μm, 5.5 ± 0.7 μm, and 7.5±0.23μminR.rattus,whereasitwas38 ± 5.8μm,124 ±4.7μm,4 ±0.21μm,and 4.2 ± 0.17 μm in M. shawi. In R. rattus and M. shawi, the outermost cells of the corneal epithelium are mostly polygonal and hexagonal in shape with nearly regular borders and show a dense pattern of microplicae with different scatter electron that exhibits three and two polymorphic appearances, respectively. Type A: numerous light cells with dense microplicae; type B: many dark cells with a moderate density of microplicae, and type C: few dark cells with a less density of microplicae are found in R. rattus; whereas, types A and B are found in M. shawi. In both investigated species, the epithelial cells are characterized by some structural components, such as glycocalyx, fibrous components and tight junction between these cells, to resist the impact of the external stressed factors and to protect the underlying tissue, as well as to maintain an excellent transparency of the cornea. Among these structures, the cytokeratin filaments are the major components of the cytoplasm of the corneal epithelial cells (basal, polygonal, wing and squamous cells). Actin filaments are also found in the corneal epithelial cells, but they are prominent within the apical epithelial cells. In R. rattus, the stroma is formed of an outer lamellar zone and an inner lamellar one; the latter is thicker and characterized by its interfibrillar spaces between the bundles of wavy dissociated collagen fibrils, which are arranged in an orthogonal manner. In M. shawi, however, the stroma is formed of one lamellar zone of flattened bundles of highly wavy and branched collagen fibrils, which are composed of perpendicular fibrillae alternating with longitudinal ones. In R. rattus, the SEM showed that the endothelial cell surfaces are slightly bulging with many blebs, whereas in M. shawi, it showed that the surfaces of the endothelial cells are flattened and nearly smooth. In conclusion, the transparency of the cornea, may be highly attributed to the increase in the thickness of the stroma, the presence of stromal interfibrillar spaces and the case of the stromal swelling. These aforementioned features are found in the corneal stroma of R. rattus, which live in different habitats of varying degrees of density such as water and dry or humid air, whereas these features are lacking in M. shawi, which live only in arid zones.

Comparative studies on the corneal structural adaptation of two rodents inhabiting different environments

The corneas of Rattus rattus and Meriones shawi are composed of three main layers; an outer epithelium, a middle stroma (basement membrane, total stroma and Descemet’s membrane) and an inner endothelium. The mean thickness of the epithelium, total stroma, Descemet’s membrane, and endothelium was about 52 ± 7.3 μm, 275 ±18.7 μm, 5.5 ± 0.7 μm, and 7.5±0.23μminR.rattus,whereasitwas38 ± 5.8μm,124 ±4.7μm,4 ±0.21μm,and 4.2 ± 0.17 μm in M. shawi. In R. rattus and M. shawi, the outermost cells of the corneal epithelium are mostly polygonal and hexagonal in shape with nearly regular borders and show a dense pattern of microplicae with different scatter electron that exhibits three and two polymorphic appearances, respectively. Type A: numerous light cells with dense microplicae; type B: many dark cells with a moderate density of microplicae, and type C: few dark cells with a less density of microplicae are found in R. rattus; whereas, types A and B are found in M. shawi. In both investigated species, the epithelial cells are characterized by some structural components, such as glycocalyx, fibrous components and tight junction between these cells, to resist the impact of the external stressed factors and to protect the underlying tissue, as well as to maintain an excellent transparency of the cornea. Among these structures, the cytokeratin filaments are the major components of the cytoplasm of the corneal epithelial cells (basal, polygonal, wing and squamous cells). Actin filaments are also found in the corneal epithelial cells, but they are prominent within the apical epithelial cells. In R. rattus, the stroma is formed of an outer lamellar zone and an inner lamellar one; the latter is thicker and characterized by its interfibrillar spaces between the bundles of wavy dissociated collagen fibrils, which are arranged in an orthogonal manner. In M. shawi, however, the stroma is formed of one lamellar zone of flattened bundles of highly wavy and branched collagen fibrils, which are composed of perpendicular fibrillae alternating with longitudinal ones. In R. rattus, the SEM showed that the endothelial cell surfaces are slightly bulging with many blebs, whereas in M. shawi, it showed that the surfaces of the endothelial cells are flattened and nearly smooth. In conclusion, the transparency of the cornea, may be highly attributed to the increase in the thickness of the stroma, the presence of stromal interfibrillar spaces and the case of the stromal swelling. These aforementioned features are found in the corneal stroma of R. rattus, which live in different habitats of varying degrees of density such as water and dry or humid air, whereas these features are lacking in M. shawi, which live only in arid zones.

Characterization of CD8+T Cells and Microenvironment in Oral Lesions of Human Immunodeficiency Virus-Infected Persons with Oropharyngeal Candidiasis

Oropharyngeal candidiasis (OPC), the most common oral infection in human immunodeficiency virus-positive persons, correlates with reduced blood CD4+ T cells. In those with OPC, CD8+ T cells accumulate at the lamina propria-epithelium interface at a distance from the organism at the outer epithelium. The present study aimed to characterize the tissue-associated CD8+ T cells and tissue microenvironment in both OPC+ and OPC- persons. The results show that the majority of CD8+ T cells possess the alphabeta T-cell receptor, the thymus-derived alphabeta CD8 antigen heterodimer, and similar levels of the alpha(4)beta(7), alpha(4)beta(1), and alpha(e)beta(7) homing receptors. Studies to evaluate the tissue microenvironment showed that in OPC+ persons, the adhesion molecule for T cells to enter mucosa, mucosal addressin cell adhesion molecule, is significantly increased, whereas E-cadherin, which allows T cells to migrate through mucosa, is significantly decreased compared to OPC- persons. These results continue to support a role for CD8+ T cells against OPC under conditions of reduced numbers of CD4+T cells, with susceptibility to infection potentially associated with a dysfunction in mucosal CD8+ T-cell migration by reduced tissue-associated E-cadherin.

Larval Cryptothelea gloverii (Lepidoptera: Psycidae), an arthropod predator and herbivore on Florida citrus

The orange bagworm (OBW), Cryptothelea gloverii (Packard) (Lepidoptera: Psychidae) was previously reported feeding on citrus fruit and foliage and preying upon the camphor scale Pseudaonidia duplex (Cockerell) (Homoptera: Coccidae). In this study using laboratory assays, OBW preyed upon citrus rust mite, Phyllocoptruta oleivora (Ashmead) (Acari: Eriophyidae) and consumed eggs and adults of both P. oleivora and Panonychus citri (McGregor) (Acari: Tetranychidae), two important pest mites on Florida citrus. OBW was also observed to feed on the purple scale, Lepidosaphes beckii (Newman) (Homoptera: Diaspididae) and on a fungus (Penicillium sp.). OBW fed on orange and grapefruit leaves by starting from the border and eating part of the leaf, by chewing holes, or consuming the outer epithelium of either the axial or abaxial surface of the leaf without penetrating through the leaf. OBW was observed in orange orchards in association with fruit extensively russeted by P. oleivora feeding. Laboratory assays revealed that OBW larvae preferred to feed on oranges infested with P. oleivora rather than on clean fruits that were free of mite feeding damage. Feeding damage to citrus fruit by OBW larvae results in one to several holes being eaten into the rind or albedo, without damage to the fruit sacs.

Functional morphology of the mantle of Nautilus pompilius (Mollusca, Cephalopoda)

This study presents histological and cytological findings on the structural differentiation of the mantle of Nautilus pompilius in order to characterize the cells that are responsible for shell formation. The lateral and front mantle edges split distally into three folds: an outer, middle, and inner fold. Within the upper part of the mantle the mantle edge is divided into two folds only; the inner fold disappears where the hood is attached to the mantle. At the base of the outer fold of the lateral and front mantle edge an endo-epithelial gland, the mantle edge gland, is localized. The gland cells are distinguished by a distinct rough endoplasmic reticulum and by numerous secretory vesicles. Furthermore, they show a strong accumulation of calcium compounds, indicating that the formation of the shell takes place in this region of the mantle. Numerous synaptic contacts between the gland cells and the axons of the nerve fibers reveal that the secretion in the area of the mantle edge gland is under nervous control. The whole mantle tissue is covered with a columnar epithelium having a microvillar border. The analyses of the outer epithelium show ultrastructural characteristics of a transport active epithelium, indicating that this region of the mantle is involved in the sclerotization of the shell. Ultrastructural findings concerning the epithelium between the outer and middle fold suggest that the periostracum is formed in this area of the mantle, as it is in other conchiferan molluscs.

Expression of Protein Kinases C βI, βII, and VEGF during the Differentiation of Enamel Epithelium in Tooth Development

Protein kinase C (PKC) is an important molecule involved in various cell function, and mediates induced secretion of vascular endothelial growth factor (VEGF). It is hypothesized that PKC and VEGF may be associated with tooth development. Using the laser microdissection method and real-time reverse-transcription-polymerase chain-reaction (RT-PCR), we investigated the expression of PKC betaI and betaII, VEGF, and amelogenin (used as a marker of differentiation to ameloblasts) in the inner and outer enamel epithelia, stellate reticulum, and dental papilla in each stage of the dental germ. We found that the expression levels of PKC betaI and betaII were increased in the inner enamel epithelium during the early bell stage. In addition, the increased expression levels of PKC betaI and betaII were accompanied by increased VEGF expression. These results indicate that PKC betaI, betaII, and VEGF are closely associated with the differentiation of the inner enamel epithelium to ameloblasts.

Histological description of tooth formation in adult Eretmodus cf. cyanostictus (Teleostei, Cichlidae)

The Eretmodini, a tribe of closely related cichlids (Teleostei, Cichlidae) originating from Lake Tanganyika, possess oral tooth shapes ranging from conical (in Tanganicodus) over cylindrical (in Spathodus) to spatulate (in Eretmodus). Prior to a study aiming to understand how these distinctly different tooth shapes can be acquired in such closely related taxa, a detailed histological study was required of tooth formation in a representative of the eretmodines. Here, we present a histological description of replacement tooth development in Eretmodus cf. cyanostictus. Using light-microscopic observations on semithin as well as on ground sections, microradiographs and stereo-microscopic observations of both alizarine red S stained and unstained jaws we can conclude that tooth formation in adult E. cf. cyanostictus roughly corresponds with what is known for teleost tooth development in general. Remarkable features include the localization and shape of the epithelial downgrowth, the transient presence of a layer intermediate between inner dental epithelium (IDE) and outer dental epithelium (ODE), the asymmetric shape of the enamel organ, the fact that the pulp cavity recedes in front of the forming enameloid during enameloid formation, and finally, the pattern of matrix mineralisation and maturation, and the presence of pigment in the enameloid. The observation that the enamel organ in adult E. cf. cyanostictus develops asymmetrically is significant for understanding tooth shape variation in the Eretmodini.

Histology and Ultrastructure of the Equine Lingual Tonsil. I. Crypt Epithelium and Associated Structures

The microstructural and ultrastructural features of the equine lingual tonsil were studied in five young horses. Located at the root of the tongue it presented an irregular surface with rounded elevations, numerous folds and crypts. Stratified squamous non-keratinized epithelium lining its outer surface was modified by heavy infiltration of lymphoid cells to form reticular epithelium within the crypt. The latter implies a role in initiating and maintaining immune responses to incoming infectious agents and antigens. Lamellated structures resembling Hassall's corpuscle were observed towards the outer surface epithelium. Microplicae were visible by scanning electron microscopy on the surface of both the outer and reticular epithelia. No microvillus cells resembling M cells were observed. The stratum superficiale of the reticular epithelium showed strong affinity for Soybean (SBA), Phosphocarpus tetragonolobus 1 (WBA 1), Ulex europaeus (UEA) and Griffonia simplicifolia 1 isolectin-B4 (GS1-B4). The characteristic lectin binding patterns may be useful for embryological and microbiological investigations. Vimentin filaments were not detected consistent with absence of M cells. Mucus glandular acini in the deeper lamina propria mucosae contained glycogen, acidic, neutral and weakly sulphated mucopolysaccharides. Transmission electron microscopy revealed that the layers of the outer surface and reticular epithelia shared characteristic features except the stratum superficiale, which had nuclei of varying shapes and an abundance of cell organelles. A few mast cells with electron lucent granules and myelinated nerve fibres were localized in the deeper portion.

Immunohistochemical expression of p63 in human prenatal tooth primordia

The aim of this study was to investigate the expression of the p63 gene in normal human tooth buds at different gestational stages. This is the first detailed study of p63 expression in normal human prenatal tooth primordia. The material consisted of sections of the midaxial tissue block from the cranial base of three human fetuses of gestational ages (GA) 11, 15, and 21 weeks. The sections included tooth primordia representing cap stages and bell stages of human tooth morphogenesis. In the present study, immunostaining was carried out using the primary antibody, monoclonal mouse anti human p63 protein, clone 4A4. The sections were counterstained with hematoxylin Mayer. p63 immunoreactivity was identified by microscopy. The study showed a positive reaction of p63 in both the cap stage and the bell stage. In both stages, positivity was observed in the cells of the oral mucosa, the inner and outer enamel epithelium, and in the primary and secondary dental lamina. In the early cap stage, there is a strong positive reaction to p63 in the enamel knot, but not in the late cap stage. We suggest that p63 may have an important regulatory function in the enamel knot.

Zona Localization of Shell Matrix Proteins in Mantle of Haliotis tuberculata (Mollusca, Gastropoda)

Organic matrix from molluscan shells has the potential to regulate calcium carbonate deposition and crystallization. Control of crystal growth thus seems to depend on control of matrix protein secretion or activation processes in the mantle cells, about which little is known. Biomineralization is a highly orchestrated biological process. The aim of this work was to provide information about the source of shell matrix macromolecule production, within the external epithelium of the mantle. An in vivo approach was chosen to describe the histologic changes in the outer epithelium and in blood sinus distribution, associated with mantle cells implicated in shell matrix production. Our results characterized a topographic and time-dependent zonation of matrix proteins involved in shell biomineralization in the mantle of Haliotis.

Chemico‐structure of the organophosphatic shells of siphonotretide brachiopods

The organophosphatic shell of siphonotretide brachiopods is stratiform with orthodoxly secreted primary and secondary layers. The dominant apatitic constituents of the secondary layer are prismatic laths and rods arranged in monolayers (occasionally in cross‐bladed successions), normally recrystallized as platy laminae. Sporadically distributed, interlaminar, lenticular chambers, containing apatitic meshes of laths and aggregates of plates and spherulites, probably represent degraded, localized exudations of glycosaminoglycans (GAGs) with dispersed apatite.The shells of Helmersenia and Gorchakovia are perforated by canals with external depressions (antechambers) that possibly contained chitinous tubercles in vivo. The immature shell of Siphonotreta and most other siphonotretids is similarly perforated and pitted; but the mature part bears recumbent, rheomorphic, hollow spines that grew forward out of pits. Internally, spines pierce the shell as independent structures to terminate as pillars in GAGs chambers. Spines and pillars were probably secreted by collectives of specialized cells (acanthoblasts) within the mantle.The shell of the oldest siphonotretide, Schizambon, is imperforate but the ventral valve has a pedicle foramen that lies forward of the posterior margin of the juvenile valve. This relationship characterizes all siphonotretides, suggesting that the pedicle, in vivo, originated within the ventral outer epithelium and not from the posterior body wall as in lingulides.

The ontogeny of MHC class I expression in rainbow trout ( Oncorhynchus mykiss)

In the present study, clonal rainbow trout ( Oncorhynchus mykiss) embryos and larvae were assayed for the expression of key molecules involved in specific cell-mediated cytotoxicity using an anti-MHC class I monoclonal Ab and by RT-PCR using specific primers derived from classical MHC class I (class Ia), TCR and CD8. Whereas RT-PCR revealed that MHC class Ia and CD8 were expressed from at least 1 week after fertilisation (p.f.) on, TCR expression was detectable from 2 weeks p.f. Immunohistochemistry indicated an early and distinct expression of MHC class I protein in the thymus. Positive lymphoid, epithelial and endothelial cells were found in the pronephros, in the spleen and in the inner and outer epithelia at later stages. Whereas in older rainbow trout the intestine is counted among the organs of the highest class I expression, during ontogeny it was the last site (39 days after hatching) where such expression was detectable. Knowledge on the appearance of the assayed key molecules during fish development is relevant for the pathogenesis of infections as well as for early vaccine delivery. Besides such information regarding the development of the adaptive immune system, immunohistochemistry revealed that in early larvae MHC class I was expressed in neurons whereas in older rainbow trout this was not observed.

The microstructure of the fibrous layer of terebratulide brachiopod shell calcite

We investigated the ultrastructure of the secondary layer of the calcite shell of the terebratulide brachiopod Megerlia truncata with SEM and electron beam backscattering diffraction. The material of the secondary layer is an inorganic/organic fibre composite. Each individual cell of the outer epithelium secrets a single crystal confined in a protein sheath. The morphological fibre axes of the single crystals are almost parallel to the shell surface. The fibrous growth occurs in arbitrary directions perpendicular to the triad symmetry direction of calcite. Accordingly, the fibres form a cylindrical \fibre texture, with the texture axis perpendicular to the shell surface. The curvature of the fibres is caused by lateral displacements or rearrangements of the secreting cell array during growth. In these events the existing crystal lattice is not distorted - it is the substrate for continued crystal growth from the cell, irrespective of direction.

Histochemical localization of cholinesterase activity in the dental epithelium of guinea pig teeth.

Cholinesterase is known for its remarkable diversity in distribution and function. An association of this enzyme with proliferative and morpho-differentiating tissues has been reported in several species. Here we report on the first evidence of the presence of cholinesterase in the enamel organ of continuously erupting incisors and molars of the guinea pig. Frozen sections of the incisors and molars of the guinea pig were incubated for histochemical demonstration of cholinesterase activity by means of the thiocholine method as described by Karnovsky and Root. The cholinesterase activity was observed in several types of cells of the dental epithelium; cells forming the basal portion of the enamel organ, outer enamel epithelium and maturation stage ameloblasts of both the incisors and molars. In the crown analogue side, the outer enamel epithelial cells gained strong reactions for cholinesterase and maintained the reaction throughout the secretory and maturation stages of amelogenesis. In contrast, cholinesterase reactions were lacking in the inner enamel epithelium, pre-ameloblasts, and secretory ameloblasts. In the early stage of enamel maturation, ameloblasts began to show positive reactions for cholinesterase, which was upregulated in the incisal direction. Although both tooth types showed similar reactive patterns for cholinesterase at the growing ends, maturation ameloblasts depicted a different pattern of staining displaying the reactions only sporadically in molars. These data indicate the role of cholinesterase in the enamel organ in tooth morphogenesis and function of guinea pig teeth.

Gonadotropin releasing hormone-1 expression in incisors of mice.

GnRH-1 is a decapeptide hormone that regulates gonadal maturation and fertility. In brain, GnRH-1 is secreted by neurons residing mainly in the preoptic/hypothalamic area. These neurons arise from cells in the nasal placode during embryonic development. GnRH-1 mRNA and peptide in the nonhypothalamic region have been described, suggesting other functions of GnRH-1. This paper describes for the first time the expression of GnRH-1 in developing incisors in mice. At embryonic day (E) 12.5, GnRH-1 mRNA and peptide were localized in cells in oral and dental epithelia. At postnatal day (P) 6, before incisor eruption, GnRH-1 was expressed in cells in dental epithelial-derived structures that include the papillary layer, outer dental epithelium, stellate reticulum, stratum intermedium, and enamel-secreting ameloblast cell layer. GnRH-1 expression correlated with cell maturity, becoming stronger in cells farther away from the proliferative zone. From E12.5 through P6, GnRH-1 expression was not detected in neural crest-derived dental mesenchyme or in mesenchyme-derived structures that include dental papilla, dental follicle, and dentin-secreting odontoblast. In addition, GnRH-1 expression was not detected in molars, indicating that expression of GnRH-1 is differentially regulated in incisor vs. molars, with only the former exhibiting continuous growth in this species. In homozygous hypogonadal mice at P1, GnRH-1 peptide expression was not detected, yet incisors were present. However, morphological changes in cells between dental follicle and ameloblast cell layer were noted. Taken together, our results indicate that GnRH-1 expression, although not essential for initiation and formation of incisors, may be important in maturation and/or maintenance of these placodally derived structures.

Society for Reproductive Biology Founders' Lecture 2003. The making of an embryo: short-term goals and long-term implications.

During early development, the eutherian mammalian embryo forms a blastocyst comprising an outer trophectoderm epithelium and enclosed inner cell mass (ICM). The short-term goal of blastocyst morphogenesis, including epithelial differentiation and segregation of the ICM, is mainly regulated autonomously and comprises a combination of temporally controlled gene expression, cell polarisation, differentiative cell divisions and cell-cell interactions. This aspect of blastocyst biogenesis is reviewed, focusing, in particular, on the maturation and role of cell adhesion systems. Early embryos are also sensitive to their environment, which can affect their developmental potential in diverse ways and may lead to long-term consequences relating to fetal or postnatal growth and physiology. Some current concepts of embryo-environment interactions, which may impact on future health, are also reviewed.

Adenoviral vector gene delivery via the round window membrane in guinea pigs.

We have found that damage from a local anesthetic solution containing phenol permitted beta-galactosidase (beta-gal) gene delivery to the guinea pig inner ear via the round window membrane (RWM). RWM damage was evident as degeneration of the outer epithelium. After adenovirus lacZ vector was applied to the damaged RWM, immunohistochemistry showed strong beta-gal expression in the RWM, mesothelial cells, organ of Corti, spiral limbus, spiral ligament and spiral ganglion. In the vestibular labyrinth, expression was seen in the sensory and supporting cells, transitional cells, and the dark-cell area. Thus, adenovirus can transfect a variety of inner ear cells in the guinea pig through a damaged RWM.

Insulin-like system and growth regulation in the Pacific oyster Crassostrea gigas: hrIGF-1 effect on protein synthesis of mantle edge cells and expression of an homologous insulin receptor-related receptor

The involvement of molecules belonging to the insulin/IGF family in regulation of growth has been investigated in the Pacific oyster Crassostrea gigas. In vitro biological effects of human recombinant IGF-1 (hrIGF-1) on mantle edge cells, involved in oyster shell and soft body growth, were studied over an annual cycle. In mantle edge cells hrIGF-1 stimulates protein synthesis of 56 ± 5.1% over basal for 10 −10 M in September with in addition a clear dose-effect corresponding to the highest shell growth period, and 57.5 ± 3.45% over basal for 10 −11 M in March and 51 ± 5.4% over basal for 10 −10 M in April corresponding to the period of mantle growth. These insulin-like effects were associated with the expression of a recently identified C. gigas insulin receptor-related receptor (CIR) in mantle edge cells as demonstrated by RT-PCR. Moreover, in situ hybridisation (ISH) confirmed this expression at the level of the inner and outer epithelia involved in mantle growth and shell formation.