marginal sinus


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Related to marginal sinus: marginal sinuses

marginal sinus

Etymology: L, margo + sinus, hollow
a sinus that may encircle the placenta. Also called placental sinus.

marginal sinus

1. Considered together, the many dilated veins or venous "lakes" that collect blood in the intervillous space of the placenta; the marginal sinus drains into the uterine veins.
2. A dural sinus along the inside of the rim of the foramen magnum; it drains into the vertebral venous plexus.
3. A blood-filled sinus in the marginal zone of the spleen. In the passage from the red pulp to the white pulp, some arterial blood flows along (and percolates through) the endothelia-lined walls of the marginal sinus before entering the arterial capillary beds of the white pulp.
See also: sinus