The choroid consists mainly of a dense capillaryplexus, and of small arteries and veins carrying blood to and returning it from this plexus.
On its external surface is a thin membrane, the suprachoroid lamina, composed of delicate non-vascular lamellae—each lamella consisting of a network of fine elastic fibers among which are branched pigment cells.
During embryological development, it is derived from the neural crest.
The spaces between the lamellæ are lined by endothelium, and open freely into the , which, in its turn, communicates with the periscleral space by the perforations in the sclera through which the vessels and nerves are transmitted.
This article incorporates text in the public domain from page 1010 of the 20th edition of Gray's Anatomy (1918)
