<p>So named as they were initially found in the [[Bursa of Fabricius - Anatomy & Physiology|Bursa of Fabricius]]. They produce antibodies (Ig’s) and are associated with humoral immunity. They represent 20-30% of circulating lymphocytes. | <p>So named as they were initially found in the [[Bursa of Fabricius - Anatomy & Physiology|Bursa of Fabricius]]. They produce antibodies (Ig’s) and are associated with humoral immunity. They represent 20-30% of circulating lymphocytes. |