Important Note

Tufts ended funding for its Open Courseware initiative in 2014. We are now planning to retire this site on June 30, 2018. Content will be available for Tufts contributors after that date. If you have any questions about this please write to

Tufts OpenCourseware
PREV : Thymus of the dog at low power NEXT : Cortex and medulla of the canine thymus
Author: Paul Kwan, Ph.D.
Thymus of the dog
Description:The cortex stains darker than the medulla because the former is mostly made up of densely packed lymphocytes. The cortex also appears to have little holes in the tissue. This 'mooth-eaten" appearance is due to the presence of macrophages sitting in a clear area among the tightly packed lymphocytes. Notice the blood vessels at thr junctions between the cortex and the medulla. PK2966-97. H&E Thymus. Immune system. Dog.