[Histochemical studies of the peroxidase activity of the bursa of Fabricius of Gallus dom.; study of the enzymatic metabolism of that immunocompetent organ during its development].

By means of the technique proposed by De Robertis and Grasso (1946) for the histochemical localization of peroxidase activity, we have shown in the developing chicken Bursa of Fabricius positive cells from the 12th day onwards. They are localized in the mesenchymal network and increase during the development, reaching their top level in a period between the 18th-20th day before hatching and the 3rd day after hatching. After the first week these cells decrease and disappear during the second month. Peroxidase positive cells are tentatively identified as eosinophilic granulocytes (pseudoeosinophilic according to Romanoff); their variations should express fluctuations in the pattern of bursal granulocytopoiesis.