The behavior of bursal lymphoid follicle-associated cells after treatment with testosterone

Administration of androgens produces damage in lymphoid tissue and in the bursa of Fabricius. After IM administration of 5 mg of testosterone propionate (TP) beginning at hatching and continued during the following 4 days, a significant reduction in the bursal weights is observed. Histologically, an increase in the connective tissue is observed and cystic formations are also found. In all cysts examined, there is continuity of the cystic lumen with the free surface. The follicle-associated epithelial (FAE) cells are on the bottom of the pseudocysts and form a separation between the pseudocystic cavity and the lymphoid tissue which is still further inwards. These cells do not lose their esterase activity, even though they are often flattened. Furthermore, they disappear in the pseudocysts deprived of lymphoid tissue. A new hypothesis is advanced that the FAE cells originate from the mesenchyme with differentiation in the histiocytic line.