Effect of steroids on thymus lymphoid development in vitro

Abstract

The effect of some steroids on the lymphoid differentiation of embryonic mouse thymus glands was studied. Most of the adrenal cortex hormones tested could inhibit lymphoid differentiation when applied in low concentrations to prelymphoid 13-day glands. The most effective was corticosterone. Careful washing of the affected glands allowed them to develop normally into lymphoid organs. The application of a high dose of corticosterone produced an effect not reversed. by thorough washing. Such permanently affected glands were restituted to lymphoid organs by fusion with 13 or 15-day embryonic mouse liver or with 15-day spleen. Lymphoid glands were much less sensitive to low concentrations of corticosterone than the prelymphoid glands. The same concentration of corticosterone was more toxic to more advanced fetal glands. The sex hormones tested were practically ineffective at comparatively high doses; very high concentrations were toxic however.Basophilic cells normally found in 12 and 13-day embryonic thymus glands disappeared after corticosterone treatment even in glands which were still potentially capable of lymphoid differentiation suggesting that these cells are not stem cells.