. Text-book of normal histology: including an account of the development of the tissues and of the organs. he ciliary or outer margin of the iris in this important territory three areas may be distinguished : I, the ciliary ring; 2, the cili-FiG. 371. ary processes; 3, the ciliary muscle. The ciliary ring, or orbicu-lus ciliaris, is a circular tractabout 4 mm. in breadth, situatedimmediately in front of the eraserrata and extending to theposterior ends of the ciliary pro-cesses. This zone differs fromthe choroid in the absence ofthe choriocapillaris and in thepresence of muscular
. Text-book of normal histology: including an account of the development of the tissues and of the organs. he ciliary or outer margin of the iris in this important territory three areas may be distinguished : I, the ciliary ring; 2, the cili-FiG. 371. ary processes; 3, the ciliary muscle. The ciliary ring, or orbicu-lus ciliaris, is a circular tractabout 4 mm. in breadth, situatedimmediately in front of the eraserrata and extending to theposterior ends of the ciliary pro-cesses. This zone differs fromthe choroid in the absence ofthe choriocapillaris and in thepresence of muscular tissueprolonged from the mass of theciliary muscle ; the character ofthe stroma also changes, its bulkbeing here made up of fibrousconnective bundles instead of elastic lamellae. The ciliary processes consist of an annular series of someseventy prominent radial vascular folds which project from theinner surface of the ciliary body and arise from the confluence ofseveral of the low ridges on the ciliary ring ; after attaining a heightof about I mm., they abruptly end at the base of the iris, sinking Bm. Section of human ciliarj processes ; /, in-terstitial connective-tissue stroma, covered byretinal layers (/?); i, o, inner clear and outerpigmented layers of cells; /, fibrous tissue ofprocesses. THE EYE AND ITS APPENDAGES. 245 to the level of the underlying- ciliary muscle. The stroma of theprocesses is a continuation of the connective tissue of the orbicularzone, this layer being the true prolongation of the choroid, since themuscular tissue must be regarded as an intercalation between thesclerotic and choroid coats. The vitreous lamina is continued as adehcate homogenous membrane, 3 to 4 p. in thickness, over the innersurface of the ciliary processes. Inside this layer the internal face ofthis entire region, including the ciliary ring and the ciliary body, aswell as the iris, is covered by the deeply-pigmented rudimentarylayers of the pars ciliaris retinae, consisting of an in
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