Testosterone suppression of mesenchymal alkaline phosphatase activity and lympho-epithelial nodule formation in the bursa of Fabricius in the embryonic chick.

Abstract

AbstractThe relatively strong alkaline phosphatase activity of the subepithelial mesenchyme of the bursa during the period of lympho‐epithelial nodule formation (12–15 days of incubation) and the close association of vascular channels with surface epithelium at sites of nodule formation suggest the possible role of these factors in induction and/or development of these nodules.Experimental inhibition of nodular formation and development may be accomplished by the administration of testosterone prior to the onset of this process (e.g., 12th day of incubation). One‐tenth milliliter (2.5 mg) of testosterone propionate in sesame oil (Schering) was administered on the tenth, eleventh and twelfth days of incubation. Bursas from 136 experimental and 64 control embryos were removed on the thirteenth, fifteenth and eighteenth days of development, fixed in cold 80% ethanol and embedded in paraffin. Alkaline phosphatase activity was demonstrated by the Gomori's glycerophosphate procedure using incubation times of one‐half, two and four hours at 37°C.Testosterone administered on the twelfth day produced a moderate decrease in alkaline phosphatase activity and markedly reduced nodule formation and subsequent development. When administered on the eleventh day, however, alkaline phosphatase activity was greatly reduced and essentially complete inhibition of nodular formation was accomplished.The possible direct inhibitory effect of testosterone on alkaline phosphatase activity (and possibly other mesenchymal cell functions) and the resulting inhibition of lympho‐epithelial nodule formation during embryogenesis of the bursa of Fabricius is suggested.