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a circular or rounded flat plate; often spelled disc in names of anatomic structures.
articular disk a pad of fibrocartilage or dense fibrous tissue present in some synovial joints.
Bowman's disk one of the flat plates making up a striated muscle fiber.
choked disk papilledema.
ciliary disk pars plana.
embryonic disk (germ disk) (germinal disk) a flattened round bilaminar plate of cells in the blastocyst of a mammal, where the first traces of the embryo are seen; called also embryonic or germinal area.
herniated disk see herniated disk.
intervertebral disk the layer of fibrocartilage between the bodies of adjoining vertebrae; see also herniated disk.
intra-articular d's articular disk.
Merkel's d's small cup-shaped tactile receptors in the skin that are particularly sensitive to continuous pressure.
optic disk the intraocular part of the optic nerve formed by fibers converging from the retina and appearing as a pink to white disk in the retina; there are no sensory receptors in the region and hence no response to stimuli. Called also blind spot.
ruptured disk herniated disk.
slipped disk popular term for herniated disk.
1. A platelike mass of cells in the blastocyst from which a mammalian embryo develops. Also called embryonic shield.
2. See germinal disk.
the thickened plate from which the embryo develops in the second week of pregnancy. Scattered cells from the border of the disk migrate to the space between the trophoblast and yolk sac and become the embryonic mesoderm. The disk develops from the ectoderm and endoderm. Also called embryonic area, gastrodisk, germ disk, germinal area.
a circular or rounded flat plate. See also intervertebral disk.
a pad of fibrocartilage or dense fibrous tissue present in some synovial joints. As specialized intra-articular structures they differ from articular plates in that they have nerve and blood supplies.
a flattish area in a cleaved ovum in which the first traces of the embryo are seen. Called also germinal disk.
the lesion produced by a sudden extrusion of non-degenerate nucleus pulposus from intervertebral disks into the cervical vertebral canal as a result of trauma.
the embryo in a hen egg.
these develop on the ventrolateral aspects of the head early in fetal development. They deepen, are surrounded by the developing nasal processes, then break through into the oral cavity and become the nasal cavities.
the popular name for prolapse of the nucleus of an intervertebral disk.
emanating from or pertaining to embryo. See also embryo.
see early embryonic mortality (below).
larger cells of the mammalian blastocyst which develop into the embryo.
early embryonic mortality
death of the embryo, i.e. before it becomes a fetus; a principal cause of temporary infertility in farm livestock. Amongst causes are errors in timing of insemination, chromosomal defects, asynchronous development of the endometrium.
ability of embryonic tissues to recognize changes in their size and location and to make the necessary adjustments to form the disk-shaped assembly of appropriate structures.
embryonic stem cell
stem cell of fetal origin.
see chorionic vesicle.