For the coding genes, we further correlated their expression with the methylation status. Finally, genomic sequencing was performed on the miRNA and key candidate genes in the MDR to CX-4945 search for inactivating mutation. The human ciliary body is a multifunctional ocular tissue, located between the ora serrata and the iris. The CB is composed of the ciliary muscle and two, partly folded, neuro-epithelial layers: the non-pigmented and pigmented epithelial layers. Posterior, the NPE forms, via the ora serrata, a continuum with the neuronal retina, like the PE does with the retinal pigment epithelium. On the anterior side, the CB continues into the iris epithelium. The CB acts, through tight junctions between NPE cells, as a blood-aqueous barrier; it prevents the intercellular diffusion of large biomolecules from the blood into the aqueous humor. One of the most important functions of the CB epithelia is the production of aqueous humor. The aqueous humor is necessary to build up the intraocular pressure, which maintains the eye shape, and it nourishes avascular tissues, like the lens and the cornea. The ciliary muscle is involved in lens accommodation. The CB epithelia have also been implicated in a number of other functionalities such as neurodevelopmental processes, neuro-endocrine properties, the ocular immune privilege, and the turnover of the vitreous. The interesting, yet still controversial neuro-developmental function of the CB concerns the recent discovery of retinal progenitor cells in the pars plana and the ciliary marginal zone of the CB. Several authors report that PE cells of human, primate, porcine, rodent and chicken express a number of retinal stem cell or progenitor cell markers, such as NES, MITF, PAX6, SIX3, Rx, FGF2 and CHX10. These findings are corroborated by proliferation and differentiation of isolated retinal stem cells into neural spheres and possible photoreceptor-like cells. Subsequent reports also describe this proliferation of PE derived cells of human and rodent tissue) including expression of some retinal progenitor markers, but they fail to observe a differentiation into neurons or photoreceptors. Further investigations are warranted to fully resolve this issue. Several studies report on the expression and synthesis of multiple endocrine proteins in the CB. These include different neuropeptides, such as neurotensin, natriuretic peptides, and somatostatin, steroid-converting enzymes, transferrin, transthyretin, angiotensin, and growth factors. The synthesized endocrine molecules are most likely important in the pressure regulation and composition of the aqueous humor. The ocular microenvironment behind the NPE blood-aqueous barrier is immunosuppressive and anti-inflammatory. This minimizes ocular tissue damage and preserves clarity of vision. This immune privilege is maintained by restricting inflow of immunological molecules and cells from the innate an adaptive immune system into the eye. In addition, the aqueous humor is rich in soluble immunomodulatory factors produced by the PE cells such as CD86, TGF-beta and TSP1. Finally, a number of additional functions have been attributed to the CB, including the macromolecule production and turnover of constituents of the vitreous and accommodation of the lens by the ciliary muscle. The CB is also involved in several pathologies. The most important are glaucoma, anterior uveı¨tis/iridocyclitis, exfoliation syndrome and uveal melanoma. Since the CB is involved in IOP regulation, it might play a role in primary open angle glaucoma.