part_of part of part of has part has part has_part has quality has quality develops_from develops from contributes to morphology of anatomical entity anatomical entity scleral cell opaque camera-type eye organ part sclera http://upload.wikimedia.org/wikipedia/commons/1/1e/Schematic_diagram_of_the_human_eye_en.svg The tough, usually white, outer coat of the eyeball, covering all the posterior surface and continuous anteriorly with the cornea. [TFD][VHOG] SCTID:181163006 GAID:911 The sclera, also known as the white part of the eye, is the opaque (usually white, though certain animals, such as horses and lizards, can have black sclera), fibrous, protective, outer layer of the eye containing collagen and elastic fiber. It is derived from the neural crest. In children, it is thinner and shows some of the underlying pigment, appearing slightly blue. In the elderly, however, fatty deposits on the sclera can make it appear slightly yellow. The sclera forms the posterior five sixths of the connective tissue coat of the globe. It is continuous with the dura mater and the cornea, and maintains the shape of the globe, offering resistance to internal and external forces, and provides an attachment for the extraocular muscle insertions. The sclera is perforated by plenty of nerves and vessels passing through the posterior scleral foramen, the hole that is formed by the optic nerve. At the optic disk the outer two-thirds of the sclera continues with the dura mater (outer coat of the brain) via the dural sheath of the optic nerve. The inner third joins with some choroidal tissue to form a plate (lamina cribrosa) across the optic nerve with perforations through which the optic fibers (fasciculi). The thickness of the sclera varies from 1mm at the posterior pole to 0.3 mm just behind the rectus muscle insertions. The sclera's blood vessels are mainly on the surface, and together with the conjunctiva (which lies on top) This is a thin layer covering the sclera. Along with the vessels of the conjunctiva, those of the sclera renders the inflamed eye bright red. [WP,unvetted][Wikipedia:Sclera]. XAO:0000183 FMA:58269 ZFA:0005563 EV:0100342 VHOG:0001274 in fish, reptiles and monotremes the connective tissue of the sclera is skeletal Opaque fibrous outer layer of the eyeball[ZFA,Kardong,WP]. scleral capsule MA:0000280 scleral Seko et al demonstrate chondrogenic potential and identify this as connective tissue[DOI:10.1371/journal.pone.0003709]. UBERON:0001773 MESH:D012590 continuous with the dura mater and the cornea; The sclera forms the posterior five-sixths of the connective tissue coat of the globe. EMAPA:19027 Disease notes: implicated in rheumatoid arthritis. UMLS:C0036410 NCIT:C12784 AAO:0010354 OpenCyc:Mx4rv7yR55wpEbGdrcN5Y29ycA Wikipedia:Sclera BTO:0001606 uberon Majority derives from NC that surrounds optic cup of neurectoderm; a small temporal portion develops from the mesoderm that contributes to striated extra-ocular muscles and vascular endothelia[Rada&Johnson]. eye mesenchyme mesenchyme derived from head neural crest tunica fibrosa of eyeball