Abstract

Generally it is accepted that the plasma cell is transformed from small sensitized lymphocytes when they are met with antigen(Gowans, Roberts, however Fagraeus alleged that the plasma cells are derived from primitive reticular cell. The authors confirmed light and electron-microscopically the formation of plasma cells from reticular cell in the rat thymus after whole body irradiation and cortisone-ACTH-DOCA administration, adrenalectomy which were not immunologic procedures. For this account, we present the aging influence on the transformation of reticular cell into plasma cell. Methods and Materials Albino rats, the age of 1 month, 4 months and 8 months were used. Cortisone acetate (Upjohn) was injected 5mg intramuscularily everyday for 7 days and the rats were sacrificed 24 hours after last injection. The adrenalectomized rats were divided into 2 groups namely; first week group and 3rd week group after adrenalectomy. The thymus from normal rats or the rats received the above mentioned treatment were histologically (methylgreen pyronin and hematoxylin-eosin) and electron-microscopically observed. The results (1) It was confirmed electron-microscopically that the plasma cells were not so many but constant cell element in the thymus from all three different age groups and their distribution is confirmed in both subcapsular region or medulla. (2) A series of transformation from reticular cell into the plasma cell were observed among the newly formed pyroninophilic cells from cortisone treated rats, and the appearance was extremely distinct in the thymus of 1 month or 4 months old rats. (3) After adrenalectomy, prominent proliferation of plasma cell series occured in the rat thymus; the marked increase of mature plasma cell in the thymus from the rats of 1 month or 4 months 3 week after adrenalectomy and from the rats age of 8 months first week or 3rd week after adrenalectomy, however proliferation of transitional form of plasma cell in the thymus from the rats age of 1 month or 4 months first week after adrenalectomy. (4) The mode of plasma cell proliferation after cortisone treatment was almost same in the rats thymus from the both following groups; the one group is the rats treated with cortisone only and the other is the rats received adrenalectomy and cortisone injection.