rouleaux formation

[rōō-lō]
n.
  1. A stacklike arrangement of red blood cells in blood or in diluted suspensions of blood in which their biconcave surfaces are next to each other.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.