Regeneration Patterns of Lymphoid Follicles in the Rabbit Spleen after Sublethal X-irradiation

Abstract

Although much information has been obtained recently with regard to various follicular activities (Thorbecke et al., 1964, Hanna, 1965, Nossal et al., 1965) and to cell kinetics of small lymphocytes (Everet et al., 1964), including follicular lymphocytes (Fliedner et al., 1964), an integrated picture of lymphoid follicle histophysiology is still lacking. In the experiments to be reported in this study, follicular regeneration after sublethal X-irradiation was studied in rabbit spleen, to determine some of the basic mechanisms that may be operative in the structural dynamics of splenic lymphoid follicles. Three types of experimental conditions have been used: 1. sublethal total body irradiation (450 R) of normal rabbits, i.e. in which germinal center activity of splenic follicles is negligible, 2. similar irradiation of rabbits in which germinal center activity of splenic follicles had been induced by intravenous administration of paratyphoid B (H) vaccine, 3. local irradiation of the spleen (750 R) in otherwise shielded rabbits. Antibody responses were recorded in some groups of animals but will not be considered in detail here.