Structure of the bursa of fabricius and immune response to Brucella abortus in the chicken after neonatal gonadectomy.

The structure of the bursa of Fabricius and the immune response to Brucella abortus in Prelux chickens were studied three and six months after neonatal gonadectomy. The different structural changes and immune response were revealed in male and female chickens. In six-months-old gonadectomized males an increased volume density of lymphoid follicles and follicular medulla was found. The follicular number and the follicular diameter were increased. In three- and six-months-old orchidectomized animals, the immune response exceeded that of the nonoperated males of the same age. In ovariectomized chickens, antibody levels were lower than (three months) or equivalent to (six months) to those of nonoperated females. Histoquantitative analysis showed that the volume density of lymphoid follicles and follicular cortex decreased. The follicular number and the mean follicular diameter also decreased. Our results demonstrate that sex steroids have an immunomodulatory role and influence the size and structure of the bursa.