Optimal Elasticity of Biological Networks.

Reinforced elastic sheets surround us in daily life, from concrete shell buildings to biological structures such as the arthropod exoskeleton or the venation network of dicotyledonous plant leaves. Natural structures are often highly optimized through evolution and natural selection, leading to the biologically and practically relevant problem of understanding and applying the principles of their design. Inspired by the hierarchically organized scaffolding networks found in plant leaves, here we model networks of bending beams that capture the discrete and nonuniform nature of natural materials. Using the principle of maximal rigidity under natural resource constraints, we show that optimal discrete beam networks reproduce the structural features of real leaf venation. Thus, in addition to its ability to efficiently transport water and nutrients, the venation network also optimizes leaf rigidity using the same hierarchical reticulated network topology. We study the phase space of optimal mechanical networks, providing concrete guidelines for the construction of elastic structures. We implement these natural design rules by fabricating efficient, biologically inspired metamaterials.

Laminins and interaction partners in the architecture of the basement membrane at the dermal-epidermal junction.

The basement membrane at the dermal-epidermal junction keeps the epidermis attached to the dermis. This anatomical barrier is made up of four categories of extracellular matrix proteins: collagen IV, laminin, nidogen and perlecan. These proteins are precisely arranged in a well-defined architecture through specific interactions between the structural domains of the individual components. Some of the molecular constituents are provided by both fibroblasts and keratinocytes, while others are synthesized exclusively by fibroblasts or keratinocytes. It remains to be determined how the components from the fibroblasts are targeted to the dermal-epidermal junction and correctly organized and integrated with the proteins from the adjacent keratinocytes to form the basement membrane.

The oral mucosa: Epithelial professional phagocytes, lymphatics, telocytes, and false telocytes.

BACKGROUND: The oral mucosa protects the underlying tissue from mechanical damage as well as from the entry of exogenous particles and microorganisms. Telocytes (TCs) are disputed stromal cells featuring peculiarly long and thin processes with uneven calibre known as telopodes, which play a number of roles within the interstitia. The present study aimed to test the key markers recommended for discriminating between TCs and false TCs in samples of normal oral mucosa. METHODS: Archived paraffin-embedded oral mucosa samples were tested by means of immunohistochemistry with the following markers: CD34, D2-40, CD31 and CD68. RESULTS: The epithelial expression of CD68, D2-40 and CD34 was detected. Two subsets of CD34-expressing stromal cells were identified, large cells with telopodial processes, presumably of the hematopoietic lineage, and spindle-shaped TC-like cells. Macrophages and TC-like cells within the lamina propria expressed CD68. The lymphatic endothelia were found to express CD31 and D2-40, but not CD34. Sprouting lymphangiogenesis was demonstrated by the lymphatic endothelial tip cells, which were projecting thin processes within the connective stroma. CONCLUSIONS: The epithelial expression of CD68 suggests the professional phagocytic potential of the oral epithelium. Regarding the TCs and TC-like cells in the oral mucosa they could not be accurately distinguished from other possible cell types, neither on morphological basis (evidence of telopodes) nor by use of panels of markers which include CD34.

Morphology of mouse seminiferous tubules.

We developed a technique to analyze the high-resolution three-dimensional (3D) structure of seminiferous tubules. It consists of segmentation of tubules in serial paraffin sections of the testis by marking the basement membrane with periodic acid-Schiff or a fluorescent anti-laminin antibody followed by 3D reconstruction of tubules with high-performance software. Using this method, we analyzed testes from mice at different ages and accurately elucidated the 3D structure of seminiferous tubules, including the number and length of tubules as well as the numbers of connections with the rete testis, branching points, and blind ends. We also developed a technique to identify the precise spermatogenic stage and cellular composition of the seminiferous epithelium. It consists of the combination of lectin histochemistry for acrosomes and immunohistochemistry for specific cell markers visualized with fluorescence. Using this method, we examined seminiferous tubules from normal mice and counted the number of each cell type at each stage, and thereby established a quantitative standard for the cellular composition of the seminiferous epithelium. We then investigated seminiferous epithelia from genetically modified infertile mice deficient in certain cell adhesion molecules and revealed characteristic abnormalities in the cellular composition. We also analyzed the distribution and direction of spermatogenic waves along the length of adult seminiferous tubules as well as the site of the first onset of spermatogenesis in postnatal seminiferous tubules. These methods will be useful for investigating the structure and function of seminiferous tubules in mice and humans under normal and pathological conditions.

Identificação das proteínas interagentes de Yes-Associated protein (YAP), um efetor da via Hippo, em células epiteliais mamárias expostas à matriz extracelular rica em laminina / Identification of interacting proteins of Yes-Associated Protein (Yap) in mammary epithelial cells exposed to laminin-rich extracellular matrix

A sinalização da matriz extracelular (MEC) é essencial para a determinação do destino e comportamento de células epiteliais da glândula mamária. Entretanto, pouco é conhecido sobre os mecanismos moleculares envolvidos nesse processo. A via Hippo, uma cascata de sinalização que participa da regulação de diversos comportamentos celulares, incluindo o tamanho de órgãos, parece ser uma importante candidata a mediadora sinalização da MEC. Resultados preliminares do laboratório indicam que a arquitetura tecidual e a membrana basal, componente da MEC de epitélios e outros tecidos, influenciam a localização, concentração e atividade de YAP, uma proteína efetora da via Hippo, em células epiteliais mamárias. Neste contexto, o objetivo deste trabalho foi identificar as proteínas que interagem com Yap (ortólogo de YAP em camundongo) nas células epiteliais da glândula mamária em resposta à membrana basal. Foram utilizadas células EpH4, uma linhagem mamária não-tumoral murina, como modelo de diferenciação funcional e formação de ácinos em um ensaio de cultura tridimensional (3D). O tratamento de estruturas multicelulares 3D pré-formadas em placas nãoadesiva com uma matriz rica em laminina (lrECM) alterou a localização e o padrão subcelular de Yap, assim como a expressão gênica de membros da via Hippo e dos alvos de Yap, mas não alterou a expressão das proteínas da via em nível de proteína. O ensaio de co-imunoprecipitação (CoIP) seguida de análise por espectrometria de massas identificou um conjunto diferencial de proteínas que interagem com Yap na fração citoplasmática de células EpH4 cultivadas na ausência ou na presença de lrECM em um modelo de ECM-overlay. Uma análise realizada junto à database KEGG Pathways revelou que os possíveis interagentes Yap nas células cultivadas não-tratadas com lrECM participam de processos relacionados à proteólise mediada por ubiquitina, enquanto nas células expostas à lrECM os possíveis interagentes estão associados a processos metabólicos e são especialmente proteínas-chave do metabolismo de lipídios. A busca na plataforma de redes de interação STRING não identificou trabalhos que destaquem a interação de Yap com estas proteínas. A plataforma Vizit indica a participação de Yap em processos relacionados à síntese e atividade de lipídios e hormônios, o que reforça as evidências de que está pode ser uma nova função de Yap ainda não explorada em detalhes. A fim de se obter resultados complementares à CoIP, padronizamos o ensaio de identificação por biotinilação dependente de proximidade (BioID) em células embrionárias de rim humano da linhagem 293FT. As proteínas isoladas por pulldown foram identificadas por espectrometria de massas e uma análise junto à database Gene Ontology indicou que os possíveis interagentes de Yap nestas células são em sua maioria proteínas relacionadas à via Hippo, o que reforça a robustez do ensaio. Nós pretendemos transpor este sistema para as células EpH4. A expectativa é que, em conjunto, estes resultados nos orientem em projetos futuros para compreender os mecanismos de sinalização da MEC na morfogênese e diferenciação da glândula mamária

Extracellular matrix (ECM)-signaling is crucial for determination of epithelial cell fate and behavior in the mammary gland. However, little is known about the molecular mechanisms involved in these processes. The Hippo pathway, a signaling cascade involved in the regulation of several cellular processes, including organ size, seems to be an important candidate as a mediator of this signaling. Our preliminary results indicate that the tissue architecture and the basement membrane, an ECM component of epithelia and other tissues, influence the location, level and activity of YAP, an effector of the Hippo pathway. In this context, the goal of this work was to identify the proteins that interact with Yap (ortholog of YAP in mouse) in mammary epithelial cells in response to the basement membrane. We used EpH4 cells, a nontumoral murine mammary cell, in a functional differentiation and acini-forming in tridimensional (3D) culture assay. Treatment of 3D multicellular structures pre-formed on nonadhesive plates with a laminin-rich extracellular matrix (lrECM) altered the subcellular localization and pattern of Yap, as well as gene expression of Hippo pathway proteins and Yap targets, but did not altered the expression of the pathway members at the protein level. Coimmunoprecipitation (CoIP) followed by mass spectrometry analysis identified a differential set of proteins interacting with Yap in cytoplasmic fractions of EpH4 cells in the absence or presence of lrECM in an ECM-overlay culture model. An analysis performed with the KEGG Pathways database revealed that putative Yap interactors in non-treated cells participate in processes related to ubiquitin-mediated proteolysis, whereas in cells exposed to lrECM Yap interactors are associated to metabolic processes and are mainly key-proteins of metabolism of lipids and carbohydrates. A search in interaction networks platform STRING did not identify previous works that showing the interaction of Yap with these proteins. Vizit platform indicated the participation of Yap in processes related to the synthesis and activity of lipids and hormones, which reinforces the evidences that Yap can play a novel poorly explored role. To obtain complementary results to CoIP, we devised the proximity-dependent biotinylation identification (BioID) assay on embryonic renal cells of 293FT cell line. Pulldown-isolated proteins were identified by mass spectrometry and an analysis performed with Gene Ontology database revealed that putative Yap interactors are Hippo pathway-related proteins, which reinforces the robustness of the assay. We intend to transpose this system to the EpH4 cells. We expect that, together, these results will guide us in future projects to understand the signaling mechanisms of ECM in mammary gland morphogenesis and differentiation

Scaling relationships and vessel packing in petioles.

PREMISE OF THE STUDY: While tradeoffs among mechanical and conductive functions have been well investigated in woody stems, these tradeoffs are relatively unexplored in petioles, the structural link between stems and laminas. We investigated size-independent scaling relationships between cross-sectional areas of structural and vascular tissues, relationships between tissue areas of xylem and phloem, vessel packing within xylem, and scaling of vascular and structural tissues with lamina traits. METHODS: We examined allometric relationships among petiole tissues and as a function of lamina and petiole size variation on eleven species of Pelargonium. From transverse sections of methacrylate-embedded tissue, we measured the cross-sectional areas of all tissues within the petiole and vessel lumen, and cell wall areas of each vessel. Allometric scaling relationships were analyzed using standardized major axis regressions. KEY RESULTS: Pelargonium petiole vessels were packed as predicted by Sperry's packing rule for woody stems. In contrast to woody stems, there was no evidence of a tradeoff between vessel area and fiber area. Within cross-sections, more xylem was produced than phloem. Among bundles, xylem and phloem scaling relationships varied with bundle position. Except for lamina dry mass and petiole fiber cross-sectional area, petiole and lamina traits were independent. CONCLUSIONS: Petioles share vascular tissue traits with stems despite derivation from leaf primordia. We did not find evidence for a tradeoff between structural and vascular tissues, in part because fibers occur outside the xylem. We propose this separation of conduction and support underlies observed developmental and evolutionary plasticity in petioles.

In vivo skin reactions from pulsed-type, bipolar, alternating current radiofrequency treatment using invasive noninsulated electrodes.

BACKGROUND: Bipolar, alternating current radiofrequency (RF) conduction using invasive noninsulated electrodes consecutively generates independent tissue coagulation around each electrode and then, the converged coagulation columns. METHODS: Two pulsed-type RF models at the on-time pulse width/pulse pack of 30 and 40 milliseconds were designed to amplify the early stage of RF-induced tissue reaction using hairless mouse skin in vivo. Then, structural and ultrastructural changes were evaluated in hairless mouse skin samples at baseline and immediately 1 day, 3 days, 7 days, and 14 days after treatment. RESULTS: Immediately after pulsed-RF treatment, a few chrysanthemum-like zones of electrothermal coagulation and hypereosinophilic collagen fibers were found in the dermis and dermo-subcutaneous fat junction. Histochemical staining for periodic acid-Schiff and immunohistochemical staining for type IV collagen revealed marked thickening of basement membranes. Transmission electron microscopy demonstrated that pulsed-RF treatment resulted in higher electron-dense and remarkably thicker lamina densa, as well as increases in anchoring fibrils, compared with untreated control specimens. Furthermore, CD31-positive blood vessels were smaller in size with a slit-like luminal appearance, without excessive damage to endothelial cells. CONCLUSION: Our data indicated that pulse-type, bipolar RF energy induces structural and ultrastructural changes in basement membranes and vascular components in hairless mouse skin.

The arrector pili muscle, the bridge between the follicular stem cell niche and the interfollicular epidermis.

Proximally, the arrector pili muscle (APM) attaches to the follicular stem cell niche in the bulge, but its distal properties are comparatively unclear. In this work, a novel method employing an F-actin probe, phalloidin, was employed to visualize the APM anatomy. Phalloidin staining of the APM was validated by comparison with conventional antibodies/stains and by generating three-dimensional reconstructions. The proximal attachment of the APM to the bulge in 8 patients with androgenic alopecia was studied using Masson's trichrome stain. Phalloidin visualized extensive branching of the APM. The distal end of the human APM exhibits a unique "C"-shaped structure connecting to the dermal-epidermal junction. The proximal APM attachment was observed to be lost or extremely miniaturized in androgenic alopecia. The unique shape, location, and attachment sites of the APM suggest a significant role for this muscle in maintaining follicular integrity. Proximally, the APM encircles the follicular unit and only attaches to the primary hair follicle in the bulge; this attachment is lost in irreversible hair loss. The APM exhibits an arborized morphology as it ascends toward the epidermis, and anchors to the basement membrane.

The suspensory apparatus of the distal phalanx in normal horses.

REASONS FOR PERFORMING STUDY: The suspensory apparatus of the distal phalanx (SADP) is functionally and clinically important. OBJECTIVES: To investigate SADP form and function and the microanatomy of its insertion zone. STUDY DESIGN: Descriptive gross and microanatomy. METHODS: The feet of 6 normal Standardbred horses were sectioned into blocks along the traditional perpendicular transverse axis and along functional axes of the SADP, decalcified and processed for staining with haematoxylin and eosin, Jones' periodic acid silver methenamine or Masson's trichrome stains. RESULTS: In traditional midline toe transverse plane sections SADP collagen bundles were irregular with an unstructured appearance. In sections made transversely along planes (70° and 30°) aligned with the long axis of the SADP, collagen bundles were arranged in linear rows. The linear bundles were continuous from their origin on parietal ridges of the distal phalanx through to the secondary epidermal lamellar basement membrane. At the parietal ridge interface the collagen bundles coalesced into smaller, strongly silver staining, linear structures that penetrated the cortical bone and merged with adjacent osteons. In proximal sagittal sections collagen bundles were also linear, angled at 70° to the ground surface. In distal sagittal sections collagen bundles were also arranged linearly but in a multi-angled, 'spokes of a wheel' arrangement, centred on the distal phalanx apex. CONCLUSIONS: Sectioning along functional axes demonstrated the true suspensory nature of the SADP connecting the parietal surface to the lamellar hoof wall. SADP/distal phalanx insertions showed penetrating fibres extending through the chondral-apophyseal interface up to and between distal phalanx osteons. Lamellar measurements made from sections perpendicular to the dorsal aspect of the distal phalanx are underestimations but if made along the longer, functional midline 70° transverse plane would accurately reflect the suspensory function of the lamellae. Laminitis pathophysiology correctly viewed as SADP degradation should inform logical, future therapeutic strategies.

The basement membrane and the sex establishment in the juvenile hermaphroditism during gonadal differentiation of the Gymnocorymbus ternetzi (Teleostei: Characiformes: Characidae).

Although there are several studies on morphogenesis in Teleostei, until now there is no research describing the role of the basement membrane in the establishment of the germinal epithelium during gonadal differentiation in Characiformes. In attempt to study these events that result in the formation of ovarian and testicular structures, gonads of Gymnocorymbus ternetzi were prepared for light microscopy. During gonadal development in G. ternetzi, all individuals first developed ovarian tissue. The undifferentiated gonad was formed by somatic cells (SC) and primordial germ cells (PGCs). After successive mitosis, the PGCs became oogonia, which entered into meiosis originating oocytes. An interstitial tissue developed. In half of the individuals, presumptive female, prefollicle cells synthesized a basement membrane around oocyte forming a follicle. Along the ventral region of the ovary, the tissue invaginated to form the ovigerous lamellae, bordered by the germinal epithelium. Stroma developed and the follicle complexes were formed. The gonadal aromatase was detected in interstitial cells in the early steps of the gonadal differentiation in both sexes. In another half of the individuals, presumptive male, there was no synthesis of basement membrane. The interstitium was invaded by numerous granulocytes. Pre-Leydig cells proliferated. Apoptotic oocytes were observed and afterward degenerated. Spermatogonia appeared near the degenerating oocytes and associated to SCs, forming testicular tubules. Germinal epithelium developed and the basement membrane was synthesized. Concomitantly, there was decrease of the gonadal aromatase and increase in the 3ß-HSD enzyme expression. Thus, the testis was organized on an ovary previously developed, constituting an indirect gonochoristic differentiation.

Determinants of optical coherence tomography-derived minimum neuroretinal rim width in a normal Chinese population.

PURPOSE: To characterize an optical coherence tomography (OCT)-derived parameter, Bruch's membrane opening-minimum rim width (BMO-MRW), and its association with demographic and clinical parameters in normal Chinese subjects. METHODS: Right eyes of 466 consecutive healthy subjects from a population-based study of Singaporean Chinese underwent Cirrus OCT imaging. The retinal internal limiting membrane (ILM) and BMO were automatically delineated using the built-in Cirrus algorithm. The standard 36 interpolated radial B-scans (72 BMO points, 5° increments) of each optic nerve head were manually extracted from the central circle (3.46-mm diameter). We used Matlab to measure the shortest distance from the BMO points to the ILM. Associations of BMO-MRW with demographic and clinical parameters were evaluated using marginal general estimating equations analysis. RESULTS: There was a slight preponderance of male subjects (50.9%), with a mean age of 54.8 ± 7.63 years. Mean BMO-MRW was 304.67 ± 58.96 µm (range, 173.32-529.23 µm), which was highly associated with OCT-derived disc area (DA) (ß = -91.78, P < 0.001) and rim area (RA) (ß = 194.31, P < 0.001), followed by spherical refractive error (SRE) (ß = -2.23, P = 0.02) and retinal nerve fiber layer (RNFL) thickness (ß = 0.5, P = 0.04), after adjusting for the associated factors such as age, sex, intraocular pressure (IOP), and vertical cup-disc ratio (VCDR). CONCLUSIONS: Disc area and RA had the strongest association with BMO-MRW, followed by SRE and RNFL thickness. The availability of this normative database will facilitate optic nerve head assessment using the BMO-MRW parameter in Chinese subjects.

Anterior lamina cribrosa insertion in primary open-angle glaucoma patients and healthy subjects.

PURPOSE: To determine using swept-source optical coherence tomography (SS-OCT) whether there are differences in the location of the anterior lamina cribrosa insertion (ALI) in primary open-angle glaucoma (POAG) patients and healthy subjects. METHODS: Fifty three eyes from 53 patients with POAG, and 53 eyes from 53 age-matched healthy subjects were included prospectively in Seoul National University Bundang Hospital. Twelve radial line B-scans centered on the optic disc in every half-clock-hour meridian were acquired using SS-OCT. The ALI position was assessed by measuring two parameters: (1) ALI distance (ALID)--the distance from the anterior scleral canal opening (ASCO) to the ALI; and (2) marginal anterior lamina cribrosa surface depth (mALCSD)--the perpendicular distance from the ASCO plane to the anterior lamina cribrosa surface. These parameters were compared between the two groups for each meridian. RESULTS: Both ALID (256 ± 54 vs. 209 ± 37 µm, mean ± SD, p < 0.001) and mALCSD (232 ± 63 vs. 187 ± 40 µm, p < 0.001) were significantly greater in the POAG group than in the normal group. The largest difference was observed at the 6.5 o'clock and 11.5 o'clock meridians for both ALID and mALCSD. Multiple regression analysis revealed a negative correlation between age and both ALID and mALCSD in the control group, and a negative correlation between mean deviation of the visual field test and both ALID and mALCSD in the POAG group. CONCLUSIONS: The ALI was displaced posteriorly in eyes with POAG compared to those of healthy controls. This finding suggests that the posteriorly located lamina cribrosa insertion is an important component of glaucomatous optic nerve excavation.

Variation of laminar depth in normal eyes with age and race.

PURPOSE: To determine if laminar depth (LD) and prelaminar tissue volume (PTV) are associated with age and race in healthy human eyes. METHODS: Optic nerve head images from enhanced depth imaging spectral-domain optical coherence tomography of 166 normal eyes from 84 subjects of African descent (AD) and European descent (ED) were manually delineated to identify the principal surfaces: internal limiting membrane, Bruch's membrane (BM), anterior sclera (AS), and anterior surface of the lamina cribrosa. These four surfaces defined the LD and PTV using Bruch's membrane opening (BMO) and AS for reference structures. Generalized estimating equations were used to evaluate whether the effect of age on each outcome was differential by race. RESULTS: When age was analyzed as a continuous variable, the interaction term between age and race was statistically significant for mean LDBMO (P = 0.015) and mean LDAS (P = 0.0062) after adjusting for axial length and BMO area. For every 1-year increase in age, the LDAS was greater on average by 1.78 µm in AD subjects and less by 1.71 µm in ED subjects. Mean PTV was lower in the older subjects (1248 × 10(6) µm(3) AD, 881 × 10(6) µm(3) ED) compared to the younger subjects (1316 × 10(6) µm(3) AD, 1102 × 10(6) µm(3) ED) in both groups. CONCLUSIONS: With increasing age, the LD changes differently across racial groups in normal subjects. The LD in ED subjects showed a significantly decreasing slope suggesting that the lamina moves anteriorly with age in this group.

The cellular origins of the outer retinal bands in optical coherence tomography images.

PURPOSE: To test the recently proposed hypothesis that the second outer retinal band, observed in clinical OCT images, originates from the inner segment ellipsoid, by measuring: (1) the thickness of this band within single cone photoreceptors, and (2) its respective distance from the putative external limiting membrane (band 1) and cone outer segment tips (band 3). METHODS: Adaptive optics-optical coherence tomography images were acquired from four subjects without known retinal disease. Images were obtained at foveal (2°) and perifoveal (5°) locations. Cone photoreceptors (n = 9593) were identified and segmented in three dimensions using custom software. Features corresponding to bands 1, 2, and 3 were automatically identified. The thickness of band 2 was assessed in each cell by fitting the longitudinal reflectance profile of the band with a Gaussian function. Distances between bands 1 and 2, and between 2 and 3, respectively, were also measured in each cell. Two independent calibration techniques were employed to determine the depth scale (physical length per pixel) of the imaging system. RESULTS: When resolved within single cells, the thickness of band 2 is a factor of three to four times narrower than in corresponding clinical OCT images. The distribution of band 2 thickness across subjects and eccentricities had a modal value of 4.7 µm, with 48% of the cones falling between 4.1 and 5.2 µm. No significant differences were found between cells in the fovea and perifovea. The distance separating bands 1 and 2 was found to be larger than the distance between bands 2 and 3, across subjects and eccentricities, with a significantly larger difference at 5° than 2°. CONCLUSIONS: On the basis of these findings, we suggest that ascription of the outer retinal band 2 to the inner segment ellipsoid is unjustified, because the ellipsoid is both too thick and proximally located to produce the band.

Morphological and functional characteristics of human gingival junctional epithelium.

BACKGROUND: This study aims to observe the morphological characteristics and identify the function characteristics of junctional epithelium (JE) tissues and cultured JE cells. METHODS: Paraffin sections of human molar or premolar on the gingival buccolingual side were prepared from 6 subjects. HE staining and image analysis were performed to measure and compare the morphological difference among JE, oral gingival epithelium (OGE) and sulcular epithelium (SE). Immunohistochemistry was applied to detect the expression pattern of cytokeratin 5/6, 7, 8/18, 10/13, 16, 17, 19, and 20 in JE, OGE and SE. On the other hand, primary human JE and OGE cells were cultured in vitro. Cell identify was confirmed by histology and immunohistochemistry. In a co-culture model, TEM was used to observe the attachment formation between JE cells and tooth surface. RESULTS: Human JE was a unique tissue which was different from SE and OGE in morphology. Similarly, morphology of JE cells was also particular compared with OGE cells cultured in vitro. In addition, JE cells had a longer incubation period than OGE cells. Different expression of several CKs illustrated JE was in a characteristic of low differentiation and high regeneration. After being co-cultured for 14 d, multiple cell layers, basement membrane-like and hemidesmosome-like structures were appeared at the junction of JE cell membrane and tooth surface. CONCLUSIONS: JE is a specially stratified epithelium with low differentiation and high regeneration ability in gingival tissue both in vivo and in vitro. In co-culture model, human JE cells can form basement membrane-like and hemidesmosome-like structures in about 2 weeks.

The collagen matrix of the human trabecular meshwork is an extension of the novel pre-Descemet's layer (Dua's layer).

BACKGROUND: The trabecular meshwork (TM) located at the angle of the anterior chamber of the eye contributes to aqueous drainage. A novel layer in the posterior part of the human cornea has recently been reported (the pre-Descemet's layer (Dua's layer (PDL)). We examined the peripheral part of this layer in relation to the origin of the TM. METHODS: The PDL and TM of 19 human donor eyes and one exenterated sample were studied. Samples were examined by light and electron microscopy (EM) for tissue architecture and by immunohistology for four matricellular proteins, five collagen types and CD34. RESULTS: EM revealed that beams of collagen emerged from the periphery of PDL on the anterior surface of the Descemet's membrane and divided and subdivided to continue as the beams of the TM. Long-spacing collagen was seen in the PDL and TM. Trabecular cells (CD34-ve) associated with basement membrane were seen in the peripheral part of the PDL and corresponded to the start of the separation of the collagen lamellae of PDL. Collagen VI was present continuously in PDL and extended into the TM. Matricellular proteins were seen predominantly in the TM with only laminin extending into the periphery of PDL. CONCLUSIONS: This study provides an insight into the origins of the collagen core of the TM as an extension of the PDL of the cornea. This finding adds to the knowledge base of the TM and cornea and has the potential to impact future research into the TM and glaucoma.