Definition: In this task, we ask you to elaborate the sentence without changing its general meaning. You can do so by explaining further the input sentence, using more precise wording, adding qualifiers and auxiliary information etc.
Input: Endothelium is a layer of cells that line the walls of the circulatory system which carries blood around the body .
Output:
Endothelium refers to cells that line the interior surface of blood vessels and lymphatic vessels , forming an interface between circulating blood or lymph in the lumen and the rest of the vessel wall .