[Mesectodermal leiomyoma. Unusual tumor of the ciliary body]. / Leiomioma mesoectodérmico. Un tumor poco frecuente del cuerpo ciliar.

BACKGROUND: Mesectodermal leiomyoma is a benign tumor of smooth muscle of the ciliary body, which is derived from the neural crest. CLINICAL CASE: We report the case of a 35-year-old Mexican woman with visually impaired and blurred vision of the right eye of 2 months duration. The clinical and imaging presuntional diagnosis was adenoma of the non pigmented epithelium of the ciliary body and it was surgically resected. Microscopically, the tumor was composed of cells with round nuclei and scant cytoplasm without atypia or mitosis, arranged in a fibrillary background. The immunohistochemical markers for vimentin, muscle specific actin, smooth muscle actin and calponin were strongly positive in the cytoplasm of the neoplastic cells, while for glial fibrillary acidic protein and S-100 protein were negative in the same cellular population. CONCLUSIONS: Mesectodermal leiomyoma of the ciliary body is benign tumor of smooth muscle extremely rare in this location. Until now, there are just 25 previous reported cases in the literature and, the main differential diagnosis is uveal malignant melanoma, therefore some eyes were enucleated. The ultrabiomicroscopy, A and B-scan imaging studies are useful in the evaluation, however, is mandatory the microsocpic examination with routine and histochemical stains as well as the use of immunohistochemical markers such as vimentin, specific muscle actin, smooth muscle actin andcalponin to stablish the smooth muscle origin of this neoplasm, and rule out other malignant neoplams such as malignant melanoma.

Antecedentes: el leiomioma mesoectodérmico es un tumor benigno excepcional que se origina en el músculo liso del cuerpo ciliar y deriva de la cresta neural. Caso clínico: se comunica el caso de una mujer de 35 años, con disminución de la agudeza visual y visión borrosa de 2 meses de evolución en el ojo derecho. El diagnóstico presuncional clínico e imagenológico fue: adenoma del epitelio no pigmentado del cuerpo ciliar, por lo que se resecó quirúrgicamente. Microscópicamente, el tumor estaba formado por células de núcleos redondos de escaso citoplasma sin atipia ni mitosis, dispuestas en una matriz fibrilar. Los inmunomarcadores para vimentina, actina músculo específica, actina de músculo liso y calponina fueron todos positivos en el citoplasma de las células neoplásicas, excepto de los inmunomarcadores para la proteína ácida gliofibrilar y la proteína S-100 que resultaron negativos en la misma población celular. Conclusiones: el leiomioma mesoectodérmico del cuerpo ciliar es un tumor benigno de músculo liso extremadamente raro en esta localización. Hasta el momento, sólo hay 25 casos informados en la bibliografía médica y su principal diagnóstico diferencial es melanoma uveal, motivo por el que algunos ojos se enuclearon. Los estudios de ultrabiomicroscopia y ecografía modos A y B son útiles en la evaluación; sin embargo, es obligado el estudio microscópico con tinciones de rutina, y el uso de marcadores inmunohistoquímicos, como los utilizados en este caso para establecer la naturaleza del músculo liso de esta neoplasia y descartar algunas otras, como el melanoma.

Comparison of tight junction protein expression in the ciliary epithelia of mouse, rabbit, cat and human eyes.

Tight junctions in the nonpigmented epithelium (NPE) of the ciliary processes and the iris vascular endothelium form the ocular blood aqueous barrier that prevents leakage of proteins, immune cells and non-immune cells of blood into the anterior chamber. We attempted to determine whether ultrastructural differences in tight junctions reported in earlier studies are reflected in the expression pattern of tight junction proteins (TJP) and whether the TJP in mice, rabbits and cats resemble those of humans. For immunohistochemistry, 10 µm thick cryosections were rehydrated in PBS and fixed in 50 mM ammonium chloride at room temperature. After rinses in PBS, the sections were incubated twice in 0.1% Triton X-100, 10% goat serum, specific primary antibody or in PBS. After rinses in PBS, the sections were incubated in FITC-conjugated secondary antibody. After rinses in PBS, the sections were mounted with Vectashield mounting medium with propidium iodide, examined and photographed using a confocal microscope. The expression patterns of TJP in ocular ciliary epithelium of human, rabbit, cat and mouse were similar. Occludin immunoreactivity was observed as a sharp line along the junction between pigmented epithelium (PE) and NPE, and along the apico-lateral surfaces of NPE. Very light staining of the ciliary stroma was observed in cat and mouse. Claudin-1 was expressed along the entire boundaries of NPE and was more distinct between PE and NPE in rabbit. The ciliary stroma showed faint staining in cat and mouse. ZO-1 showed staining between PE and NPE, and at the adjacent membrane. Moderate staining was seen in PE in cat and mouse, which suggests that claudin-1, occludin and ZO-1 are expressed along the junction between PE and NPE, and the apico-lateral border of NPE. Lack of major difference in the expression patterns among the different species is important for validating the use of rabbit, mouse and cat in studies of intraocular inflammation in humans.

Adenoma of the non-pigmented ciliary epithelium: a rare intraocular tumor with unusual immunohistochemical findings.

A case of adenoma of the non-pigmented ciliary epithelium with smooth muscle differentiation is reported. This uncommon ocular tumor affected a 36-year-old woman, and had caused decreased visual acuity and a total cataract. Ultrasound biomicroscopy disclosed an associated persistent hyperplasic primary vitreous (PHPV). Sectoral cyclectomy with removal of the mass and intracapsular cataract extraction were performed. The tumor was diffusely positive for vimentin, smooth muscle actin, NSE, and S-100, focally for CD68 and Melan-A, and was negative for desmin, EMA, HMB-45, and CD99. Occasional cells reacted for cytokeratin. The proliferation index, as assessed by Ki-67, was below 10%. The overlying non-neoplastic ciliary epithelium was positive for vimentin, NSE, and S-100. Myofilaments are not totally unexpected in ciliary adenomas; however, such a diffuse and strong positivity for smooth muscle actin, as in the present case, has only been observed in one case before, but should be considered in the differential diagnosis of these neoplasms.

Is the positive c-kit immunostaining associated with the presence of cells analogous to the intersticial cells of Cajal in the ciliary muscle?

PURPOSE: Interstitial cells of Cajal were identified in the gastrointestinal tract of several species, with close relation to the enteric nervous system. Since it was recognized that interstitial cells of Cajal express the gene product of c-kit, we performed immunohistochemistry for c-kit protein in ciliary muscle specimens of monkeys' eyes. METHODS: Eight eyes from four adult male new world monkeys (Cebus apella) were studied. After blocking endogenous peroxidase activity and nonspecific protein binding, 1:100 dilution of mouse monoclonal antibody against c-kit human oncoprotein was applied to tissues. Antigen-antibody reaction was visualized using the avidin-biotinylated horseradish peroxidase complex in each slide. RESULTS: We observed some groups of fusiform c-kit expressing cells located amongst muscle bundles of the ciliary muscle. Other pigment cells and mast cells were also observed. CONCLUSION: C-kit expressing cells observed in the ciliary muscle of Cebus apella, showed no similarity to melanocytes or mast cells and they could be associated with their gastrointestinal interstitial cells of Cajal counterpart.

Is the positive c-kit immunostaining associated with the presence of cells analogous to the intersticial cells of Cajal in the ciliary muscle? / A imunomarcação positiva para c-kit está associada com a presença de células análogas às intersticiais de Cajal no músculo ciliar?

PURPOSE: Interstitial cells of Cajal were identified in the gastrointestinal tract of several species, with close relation to the enteric nervous system. Since it was recognized that interstitial cells of Cajal express the gene product of c-kit, we performed immunohistochemistry for c-kit protein in ciliary muscle specimens of monkeys' eyes. METHODS: Eight eyes from four adult male new world monkeys (Cebus apella) were studied. After blocking endogenous peroxidase activity and nonspecific protein binding, 1:100 dilution of mouse monoclonal antibody against c-kit human oncoprotein was applied to tissues. Antigen-antibody reaction was visualized using the avidin-biotinylated horseradish peroxidase complex in each slide. RESULTS: We observed some groups of fusiform c-kit expressing cells located amongst muscle bundles of the ciliary muscle. Other pigment cells and mast cells were also observed. CONCLUSION: C-kit expressing cells observed in the ciliary muscle of Cebus apella, showed no similarity to melanocytes or mast cells and they could be associated with their gastrointestinal interstitial cells of Cajal counterpart.

OBJETIVO: As células intersticiais de Cajal estão presentes no trato gastrintestinal de diversas espécies animais, em íntima relação com o sistema nervoso entérico. Uma vez que as células intersticiais de Cajal expressam o produto do gene c-kit, realizou-se um ensaio imuno-histoquímico a fim de se verificar a marcação da proteína c-kit no músculo ciliar de amostras de olhos de macacos. MÉTODOS: Oito olhos de quatro macacos do novo mundo (Cebus apella) foram estudados. Após bloqueio da peroxidase endógena e de ligação protéica não específica, os tecidos receberam aplicação de anticorpos de camundongos antioncoproteína c-kit humana (1:100). A reação antígeno-anticorpo foi verificada através da aplicação do complexo avidina-biotinilada-peroxidase em cada lâmina. RESULTADOS: Foram observados grupos de células que expressam c-kit, localizadas entre as fibras do músculo ciliar. Mastócitos e outras células pigmentadas também foram observadas. CONCLUSÃO: Algumas células que expressam c-kit, observadas no músculo ciliar de Cebus apella, não mostraram similaridade com mastócitos ou melanócitos e podem ser classificadas como análogas das células intersticiais de Cajal gastrintestinais.

Unusual primary ocular neoplasm in a child: leiomyosarcoma of the ciliary body.

Primary uveal-tract neoplasms are extremely rare in childhood; the most common lesions found are melanocytic. We report here the case of a 7-year-old girl who underwent enucleation of the right eye with clinical suspicion of choroid melanoma as a result of a ciliary body mass that extended to the posterior chamber. Histologically, the neoplasm featured spindle cell morphology, atypia, and mitoses. The tumor expressed smooth muscle alpha actin, pan-actin HHF-35, and desmin, whereas immunohistochemistry for melanocytic markers, such as S-100, Melan-A, and HMB-45, was negative. Based on these features, the diagnosis of leiomyosarcoma of the ciliary body was firmly established. Although several leiomyomas have been reported in the literature, there are only 2 previously reported cases of primary leiomyosarcoma of the uveal tract. Immunohistochemical expression of muscle proteins allowed distinction from the most common melanocytic tumors arising in this location.

Medulloepithelioma masquerading as chronic anterior granulomatous uveitis.

CASE REPORT: We report a rare clinical case of unilateral ciliary body teratoid medulloepithelioma presented first with infantile cataract, subsequently masquerading as chronic granulomatous anterior uveitis, followed by appearance of a tumour over the iris surface. COMMENTS: Diagnosis of the tumour in the early stages allows proper management and avoids enucleation.

Caveolin-1 is up-regulated in transdifferentiated lens epithelial cells but minimal in normal human and murine lenses.

Caveolae are flask-shaped invaginations of the plasma membrane found in many cell types. Caveolae play a role in lipid transport, endocytosis, signal transduction, and cell transformation. Expression of caveolin-1, the principal component of caveolae and a regulator of caveolae-dependent signaling and endocytosis, was investigated in lens epithelial cells and lens fiber cells in wild-type (wt) and SPARC-null mice and normal human donors in vivo and in vitro. RT-PCR, immunofluorescence and immunoblot analyses of human and murine ocular tissues revealed that caveolin-1 was expressed in the corneal epithelium, corneal endothelial cells, and blood vessels of iris, ciliary body and retina, but minimal in the normal lens epithelia or fiber cells of murine and human lens. In contrast, caveolin-1 was significantly up-regulated in mesenchymal-transdifferentiated lens epithelia in SPARC-null cataract lenses. In addition, lens epithelial cells from primary culture or from cultures of immortalized lens epithelial cell lines expressed significant amounts of caveolin-1. The lens epithelial cells expressed epidermal growth factor (EGF) receptor and were responsive to EGF-mediated cell proliferation, but they did not show EGF-dependent caveolin-1 tyrosine phosphorylation. Caveolin-1 might have a role in the process of epithelial-mesenchymal transdifferentiation (EMT) in the lens, the most common cause of vision loss in human secondary cataracts.

Fas-ligand is stored in secretory lysosomes of ocular barrier epithelia and released with microvesicles.

Previously we described the release of hr44 from the ciliary epithelium to coincide with the loss of the late endosomal/lysosomal marker protein CD63 in mildly inflamed rat eyes. We showed that both proteins are released with microvesicles into the supernatant of cultured retinal pigmented epithelial cells (ARPE-19). Here we wish to determine whether there is a concomitant loss of fas-ligand (FasL) in vivo and whether ocular epithelial cells have secretory lysosomes similar to T cells, from where FasL and hr44 could derive. FasL plays an important role in immunity, immune cell homeostasis and in the maintenance of immune privilege in the eye. However the mode of release of FasL from ocular epithelial cells or its activity in the eye is not fully understood. In normal rat eyes, FasL was detected in the epithelia of the iris and ciliary body and in the anterior region of the retinal pigmented epithelium. FasL is expressed constitutively and is associated with vesicular structures in the normal ciliary epithelium but is not detectable in the ciliary epithelium of inflamed eyes. In contrast, the posterior RPE, which under normal conditions is negative for FasL and hr44 showed strong staining for both molecules in areas adjacent to sub-retinal inflammatory infiltrates. Immunofluorescence and Western blot analysis indicated that cultured ARPE-19 cells express both the soluble and membrane form of FasL. The intracellular concentration of FasL was significantly increased in cells grown in presence of interferon (INF)-gamma. The microvesicles released by cultured ARPE-19 cells and previously shown to be positive for hr44 and CD63 are also positive for membrane FasL. Expression of a recombinant fluorescent construct of FasL together with immuno-staining for CD63 demonstrated that FasL localises to the endocytic compartment of ARPE-19 cells and of melanoma cells (positive control). In cells with lysosomes devoid of specialised secretory functions (e g. HeLa cells) recombinant FasL localised to the cell membrane, demonstrating that RPE cells have secretory lysosomes. We suggest that ocular epithelial cells release soluble FasL and the membrane form of FasL with vesicles. Both forms may contribute in different ways to the effectiveness of the ocular immune response and immune privilege.

Immunolocalization of CYP1B1 in normal, human, fetal and adult eyes.

CYP1B1 is a cytochrome P450 enzyme implicated in autosomal recessive primary congenital glaucoma (PCG). The mechanism and function of CYP1B1 in the development of the PCG phenotype is unknown. Previously, investigators have reported detection of Cyp1b1 mRNA in the ciliary body and epithelium and neuroepithelium in the developing mouse eye, employing in situ hybridization techniques. Similarly, additional investigators have detected CYP1B1 mRNA in the iris, ciliary body, non-pigmented ciliary epithelial line, cornea, retinal-pigment epithelium, and retina in the human adult eye, using Northern blotting. This study was designed to immunolocalize CYP1B1 protein in the various ocular structures of normal, human fetal and adult eyes. Normal fetal and adult eyes were immunolabeled with a polyclonal antibody against human CYP1B1 using indirect immunofluorescence, and then compared with appropriate controls. The intensity of immunolabeling of the various ocular structures was assessed by qualitative and semi-quantitative techniques. In the anterior segment anti-CYP1B1 immunoreactivity (IR) was detected early in fetal development in the primitive ciliary epithelium. As well, the most intense CYP1B1 IR was in the non-pigmented ciliary epithelium. In addition, CYP1B1 IR was also present in the corneal epithelium and keratocytes, both layers of the iris pigmented epithelium, and retina. However, CYP1B1 IR was absent in the trabecular meshwork in all of the samples. In general, CYP1B1 immunolabeling in the human fetal eyes was more intense when compared to adult eyes. CYP1B1 IR was primarily immunolocalized to the non-pigmented ciliary epithelium and early in fetal development. In addition, CYP1B1 IR was not detected in the trabecular meshwork. These findings suggest that the abnormalities in the development of the trabecular meshwork in PCG may result from diminished or absent metabolism of important endogenous substrates in the ciliary epithelium due to non-functional CYP1B1 enzyme.

Distinguishing fibrovascular septa from vasculogenic mimicry patterns.

CONTEXT: Molecular analyses indicate that periodic acid-Schiff (PAS)-positive (laminin-rich) patterns in melanomas are generated by invasive tumor cells by vasculogenic mimicry. Some observers, however, consider these patterns to be fibrovascular septa, generated by a stromal host response. OBJECTIVE: To delineate differences between vasculogenic mimicry patterns and fibrovascular septa in primary uveal melanomas. DESIGN: Frequency distributions, associations with outcome, and thicknesses of trichrome-positive and PAS-positive looping patterns were determined in 234 primary uveal melanomas. Sequential sections of 13 additional primary uveal melanomas that contained PAS-positive/trichrome-negative looping patterns were stained for type I and type IV collagens, laminin, and fibronectin. Real-time quantitative polymerase chain reaction was performed on RNA from cultured uveal melanoma cells for the expression of COL1A1, COL4A2, and fibronectin. RESULTS: Trichrome-positive loops were encountered less frequently than PAS-positive loops (10% vs 56%, respectively). Death from metastatic melanoma was strongly associated with PAS-positive (P < .001) but not with trichrome-positive (P = .57) loops. Trichrome-positive loops were significantly thicker than PAS-positive loops (P < .001). The PAS-positive patterns stained positive for laminin, type I and type IV collagens, and fibronectin. Type I collagen was detected within melanoma cells and focally within some PAS-positive patterns. Real-time quantitative polymerase chain reaction revealed 3-fold, 25-fold, and 97-fold increases, respectively, in expression of COL4A2, fibronectin, and COL1A1 by invasive pattern-forming primary melanoma cells compared with poorly invasive non-pattern-forming cells. CONCLUSIONS: Fibrovascular septa are rare and prognostically insignificant in uveal melanomas, whereas vasculogenic mimicry patterns are associated with increased mortality. Type I collagen, seen focally in some vasculogenic mimicry patterns, may be synthesized by tumor cells, independent of a host stromal response.

Analysis of Bcl-2 protein expression in choroidal melanomas.

BACKGROUND: Bcl-2 protooncogene alterations are involved in tumorigenesis and may have prognostic ramifications. AIMS: To investigate normal ocular structures and choroidal melanoma for: (1) Bcl-2 protein expression (semiquantitative staining values: SI, staining intensity; PP, percentage of positive cells; and IRS, immunoreactivity score) and (2) any associations between the staining values and clinicopathological features in these lesions. MATERIALS/METHODS: Bcl-2 protein expression was analysed in 24 choroidal melanomas using immunoperoxidase staining methods. RESULTS: Bcl-2 protein expression was seen in corneal epithelium, lens epithelium, the ciliary body, and retinal cells. In these structures, the mean (SEM) values were: 1.1 (0.1), 1.6 (0.3), 1.1 (0.1), and 2.3 (0.3), respectively, for SI; 1.6 (0.2), 1.7 (0.1), 1.7 (0.2), and 1.7 (0.2) for PP, respectively; and 1.9 (0.4), 2.7 (0.5), 1.9 (0.1), and 4.0 (0.8), respectively, for IRS. Based on Bcl-2 immunoreactivity, the lesions were divided into two groups. The first group comprised 12 tumours with Bcl-2 expression. Bcl-2 expression was significantly higher in this group compared with normal ocular structures (1.5 (0.1) v 2.8 (0.2), 1.7 (0.1) v 3.5 (0.1), and 2.6 (0.3) v 9.3 (0.9) for mean (SEM) SI, PP, and IRS scores, respectively; p = 0.00). The second group comprised 12 tumours lacking Bcl-2 protein expression. There was no significant correlation between Bcl-2 protein expression and most of the clinicopathological features of these lesions. CONCLUSIONS: Bcl-2 protein expression is altered in choroidal melanomas.

Localization of ocular P2Y2 receptor gene expression by in situ hybridization.

The objective of this study was to determine the cellular localization of P2Y(2) receptor gene expression in rabbit and primate ocular tissues using the technique of non-isotopic in situ hybridization. Fresh frozen whole eye from a New Zealand White rabbit and whole eye and eyelid from a rhesus macaque were cut into 5 microm thick sections and mounted onto glass slides. In situ hybridization was performed on ocular cryosections using digoxigenin-labeled P2Y(2) receptor riboprobes. Alkaline phosphatase-conjugated anti-digoxigenin antibody was used to localize riboprobe hybridization, which was subsequently visualized by staining with a precipitating alkaline phosphatase substrate. Cytoplasmic staining indicative of antisense riboprobe hybridization to P2Y(2) receptor mRNA was observed in the palpebral and bulbar conjunctival epithelium, including goblet cells, the corneal epithelium, and in meibomian gland sebaceous and ductal cells. Staining was also observed in both layers of the ciliary body epithelium, subcapsular epithelium of the lens, and corneal endothelium. In the posterior eye, staining was observed in various layers of the retina, including ganglion cell, inner nuclear, inner segment and retinal pigment epithelium layers, in the optic nerve head, and in a variety of structures within the choroid. No specific staining of sense riboprobe was seen on any of the ocular structures. These results demonstrate that the P2Y(2) receptor gene is expressed in a variety of ocular cells types and suggest that P2Y(2) receptors are associated with diverse physiological functions throughout the eye.

Characterisation of WE-14 in porcine ocular tissue.

WE-14 is derived from the cell-specific posttranslational processing of chromogranin A (CgA) in subpopulations of neuroendocrine cells and neurons. Region- and site-specific chromogranin A, pancreastatin and WE-14 antisera were employed to study the generation of WE-14 in porcine ocular tissues. No chromogranin A or pancreastatin immunostaining was detected in ocular tissue. Immunohistochemistry detected WE-14 immunostaining in a network of nerve fibre bundles and nerve fibres throughout the limbus, cornea, iris and ciliary body with sparse nerve fibres detected throughout the choroid and sclera. Retinal analysis detected intense WE-14 immunostaining in large ovoid cells in the ganglion cell layer with weak immunostaining in a population of small cells in the inner nuclear layer; weak immunostaining was detected within the fibre layers in the inner plexiform layer. Quantitatively, the highest WE-14 tissue concentration was recorded in aqueous retinal and corneal extracts with lower concentrations in the sclera, choroid and anterior uveal tissues. Chromatographic profiling resolved a minor chromogranin A-like immunoreactant and a predominant immunoreactant co-eluting with synthetic human WE-14. This is the first study to demonstrate that WE-14 is generated in neuronal fibres primarily innervating the anterior chamber and in select cell populations in the retina.

Adenoma of the iris and ciliary body. Case report.

A case of rare tumor of the iris and ciliary body in a 24-year old woman is presented, which was diagnosed as adenoma of the nonpigmented ciliary body epithelium. The diagnosis was confirmed immunohistochemically.

Mesectodermal leiomyoma of ciliary body.

A 37-year-old woman had a mass in her left ocular globe. Uveal melanoma was suspected and enucleation was performed. Microscopically, the lesion proved to be a typical case of mesectodermal leiomyoma of the ciliary body. According to some authors, the peculiar neural appearance of this tumor could be the reflection of its probable origin from mesectodermal smooth muscle. Immunohistochemical analysis showed reactivity for muscle-specific actin and negativity for desmin, S-100 protein, HMB-45, EMA, and GFAP. Our results do not support the proposed neuroectodermical origin of this tumor, since coexpression of muscular and neural markers was not observed.

Pleomorphic adenocarcinoma of the ciliary epithelium: a clinicopathological, immunohistochemical, ultrastructural, DNA-ploidy and comparative genomic hybridization analysis of an unusual case.

PURPOSE: To describe detailed phenotypic and genotypic analysis of a pleomorphic adenocarcinoma of the ciliary epithelium (CE). CASE REPORT: An 86-year-old white woman developed an enlarging mass protruding from her previously eviscerated left eye 2 months postoperatively. Based on light and ultrastructural microscopy, the final diagnosis was a pleomorphic adenocarcinoma of the ciliary epithelium (CE). DISCUSSION: Cell proliferation indices confirmed the unusually rapid growth rate of this tumor; the peridiploid DNA content might explain the relatively low incidence of distant metastases. An imbalance of the chromosome 6 was also found by Comparative Genomic Hybridization (CGH).

Co-localization of junction-associated proteins of the human blood--aqueous barrier: occludin, ZO-1 and F-actin.

Recent studies in mouse and rabbit eyes have begun to identify the molecular constituents of tight and adherens junctions that represent the structural equivalent of the blood--aqueous barrier (BAB). These species are commonly used as experimental models to examine the pathobiology of anterior uveitis, an inflammatory condition in which the junctions of the BAB are compromised. Because it was unclear whether major molecular elements of the junctions in these species were the same as those in humans, the goal of this study was to determine if the junction related proteins ZO-1 and occludin are present in normal human ciliary epithelium and iridial vascular endothelium. To determine their presence, sections of human anterior uvea were probed in 14 normal, human, eyebank eyes immunolabelled with antibodies to ZO-1, and occludin, and confocal microscopy was used to examine them. Phalloidin staining for F-actin was also assessed. ZO-1 and occludin were both localized along the apico-lateral surfaces of the non-pigmented ciliary epithelium and the interendothelial clefts of iris blood vessels. In both locations, the distribution of occludin was more focal than seen for ZO-1. ZO-1 was also found along the apical surfaces between the pigmented and non-pigmented ciliary epithelial cell layers. The distribution of these proteins supports the notion that occludin is more specifically associated with tight junctions than is ZO-1 in the normal human BAB. No change in this distribution was found with increasing age. These data are consistent with findings reported previously in rabbit ciliary epithelium and iridial vascular endothelium, indicating the relevance of experimental induced uveitis studies in rabbit, as a model of BAB breakdown in human uveitis.