1) Membrane 2) Tissue layer 
The connective tissue that surrounds smaller vessels and capillaries. ... Eberth's perithelium, an incomplete layer of connective tissue cells encasing the blood capillaries. ... Origin: peri-+ G. Thele, nipple ... (05 Mar 2000) ... 
(per″e-the´le-әm) the connective tissue layer surrounding the capillaries and smaller vessels.
Type: Term Pronunciation: per′i-thē′lē-ŭm, -ă Definitions: 1. The connective tissue that surrounds smaller vessels and capillaries.
[n] - tissue layer around small blood vessels
noun tissue layer around small blood vessels