pars iridica retinae

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(ret'i-nă), [TA]
Grossly, the retina consists of three parts: optic, ciliary, and iridial. The optic part, the physiologic portion that receives the visual light rays, is further divided into two parts, the pigmented part (pigment epithelium) and the nervous part, which are arranged in the following ten layers: pigmented layer; layer of inner and outer segments (of rods and cones); outer limiting layer (actually a row of junctional complexes); outer nuclear layer; outer plexiform layer; inner nuclear layer; inner plexiform layer; ganglionic (cell) layer; layer of nerve fibers; and inner limiting layer. Layers 2-10 comprise the neural layer. At the posterior pole of the visual axis is the macula, in the center of which is the fovea, the area of acute vision. Here, layers 6-9 and blood vessels are absent, and only elongated cones are present. About 3 mm medial to the fovea is the optic disc, where axons of the ganglionic cells converge to form the optic nerve. The ciliary and iridial parts of the retina are forward prolongations of the pigmented layer and a layer of supporting columnar or epithelial cells over the ciliary body and the posterior surface of the iris, respectively.
Synonym(s): optomeninx
[Mediev. L. prob. fr. L. rete, a net]

pars iridica retinae

The portion of the retina on the posterior surface of the iris.
See also: pars


pl. partes [L.] a division or part.

pars ciliaris retinae
see ciliary body.
pars distalis
the major part of the anterior lobe of the pituitary gland, the adenohypophysis. It is separated from the neurohypophysis by the intraglandular cleft, the residual lumen of Rathke's pouch.
pars disseminata
the thin layer of the prostate that surrounds the urethra; as distinct from the body of the gland.
pars flaccida
the small, triangular portion of the tympanic membrane lying between the lateral process of the malleus and the margins of the tympanic incisure.
pars infundibularis
the neural stalk that connects the neurohypophysis with the hypothalamus.
pars intermedia
the part of the adenohypophysis consisting of a layer of cells contiguous with the neurohypophysis. The source of melanocyte-stimulating hormone.
pars iridica retinae
see iris1.
pars longa glandis
the long, cylindrical part of the dog glans; distinct from the bulbar part.
pars major uteri
the section of the bird's oviduct in which the egg is held while the shell is formed.
pars mastoidea
the mastoid portion of the temporal bone, being the irregular, posterior part.
pars nervosa
of the pituitary gland. See neurohypophysis.
pars optica retina
the large, posterior part of the retina which contains the nervous elements of rods, cones and optic nerve fibers.
pars petrosa
the petrous portion of the temporal bone, containing the inner ear.
pars pigmentosa
the pigmented part of the retina.
pars plana
the thin flat part of the ciliary body; the ciliary disk.
pars plicata
the folded part of the ciliary body.
pars pylorica
distal segment of the stomach or abomasum, curved behind the omasum.
pars pylorica ventriculi
the distal (aboral) third of the stomach.
pars squamosa
the flat, scalelike, anterior and superior portion of the temporal bone.
pars tensa
the drumlike part of the tympanic membrane.
pars tuberalis
a layer of cells surrounding the neural stalk of the pituitary gland and forming part of the adenohypophysis.
pars tympanica
the tympanic portion of the temporal bone, forming the anterior and inferior walls and part of the posterior wall of the external acoustic meatus.
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