embryonic disk

embryonic disk

n.

1. A platelike mass of cells in the blastocyst from which a mammalian embryo develops. Also called embryonic shield.

2. See germinal disk.

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embryonic 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.

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disk

a circular or rounded flat plate. See also intervertebral disk.

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articular 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.

choked disk

papilledema.

embryonic disk

a flattish area in a cleaved ovum in which the first traces of the embryo are seen. Called also germinal disk.

disk explosion

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.

germinal disk

the embryo in a hen egg.

intra-articular disk

articular disk.

olfactory disk

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.

slipped disk

the popular name for prolapse of the nucleus of an intervertebral disk.

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embryonic

emanating from or pertaining to embryo. See also embryo.

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embryonic death

see early embryonic mortality (below).

embryonic disk

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.

embryonic period

see embryo.

embryonic regulation

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.

embryonic vesicle

see chorionic vesicle.