Cortex of Canine Thymus

In the cortex of the thymus illions of lymphocytes are produced here each day and these are, by definition, T llymphocytes. The cortex appears darker in low power due to the tight packing of these small lymphocytes. Most of the lymphocytes here die by apoptosis and the dead cells / apoptotic bodies are removed by macrophages. Some lymphocytes migrate to the medulla and enter the circulation. In the cortex, the lymphocytes occur in clusters surrounded by epithelial reticular cells. This is a low power micrograph and not all of the features discussed can be seen easily. PK2966-14. H&E. Thymus, cortex. Immune System. Dog.