Effect of surgical bursectomy on the ellipsoid, ellipsoid-associated cells, and periellipsoid region of the chicken's spleen.

Abstract

Surgical bursectomy resulted in cellular depletion of the periellipsoid white pulp, confirming its bursa dependency. Also, in bursectomized birds, the ellipsoid could not be identified, although a small number of abnormal ellipsoid-associated cells (EAC) were observed in the periellipsoid region. The most characteristic finding was the degeneration of the EAC. Degeneration of EAC indicated that the intact bursa was mandatory for normal differentiation of cells of the periellipsoid white pulp into EAC. The promoting effect of the bursa might take place by a bursal hormone. The histological impairment of the EAC was followed by reduced carbon binding and migrating capabilities. Bursectomy resulted in a shift in bacterial phagocytosis in that many cells of the periellipsoid phagocytosed Salmonella. The reduced heterophil infiltration of the ellipsoid in bursectomized birds might be explained by the impaired granular content of the EAC. The impaired migration capability of the EAC might contribute to the low number of germinal centers in bursectomized birds.