Abstract
The incidence of thymic B cell lymphoid follicles was retrospectively studied in 62 male and 58 female healthy control beagle dogs (age 11.3 ± 4.8, range 6 to 23 months). The animals were selected from toxicological studies performed in the period 1990—2001 at the Organon labs. The animals had received vehicle treatment. Thorough microscopic examination of the thymus in hematoxylin & eosin (H&E)-stained sections resulted in an unexpectedly high overall incidence of 70% of medullary lymphoid follicles. Occasionally, these lymphoid follicles contained germinal centers. With the use of a T- and B cell marker (respectively CD3 and CD79
