. Text-book of normal histology: including an account of the development of the tissues and of the organs. illaries are tributary to theradiating veins which pass to the ciliary border, where they join thoseof the ciliary processes and finally empty into the radicles formingthe venae vorticosae. Bundles of involuntary muscle occupy the pupillary border andthe posterior zone of the stroma-layer ; these are arranged as twosets,—the annular bundles encircling the pupillary margin of the irisand constituting the sphincter of the pupil, a muscular zone aboutI mm. in width, and the few scattered rad
. Text-book of normal histology: including an account of the development of the tissues and of the organs. illaries are tributary to theradiating veins which pass to the ciliary border, where they join thoseof the ciliary processes and finally empty into the radicles formingthe venae vorticosae. Bundles of involuntary muscle occupy the pupillary border andthe posterior zone of the stroma-layer ; these are arranged as twosets,—the annular bundles encircling the pupillary margin of the irisand constituting the sphincter of the pupil, a muscular zone aboutI mm. in width, and the few scattered radially-disposed bundlesextending from the pupil towards the ciliary margin and forming anincomplete, by no means continuous, layer, the dilator pupillae. The posterior boundary layer, or vitreous lamella, appearsas a glassy structureless membrane, about 2 // in thickness, whichstretches over the posterior surface of the stroma and supportsthe pigment-layer: in the nature of its substance this structureclosely approaches elastic tissue. The pigment-layer, or pars iridica retinae, is usually so densely. Injected iris from eye of dog : F, pupillarymargin, around which capillary net-work isformed by vessels proceeding from lesser ar-terial circle. THE EYE AND ITS APPENDAGES. ^^g packed with deeply-colored particles that its real constitution ismasked. This stratum is composed of two layers, an anterior anda posterior. The anterior or outer layer is formed of radially-arranged spindle-cells which pass without interruption from theciliary border of the iris to the pupillary margin ; at the ciliaryborder the cells change their form and arrangement, becomingpolyhedral and circularly disposed and continuous with the lowpigmented elements constituting the corresponding layer of theciliary processes. The posterior layer presents a thicker zone (30-35 m) of pig-mented cells, in which the colored particles are so densely packedthat the cell-boundaries and the nuclei are completely masked,
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Keywords: ., bookcentury1800, bookdecade1890, bookpublisherphiladelphiajblipp
