Cytophotometric Characterization of Cortical and Medullary Lymphocytes in the Chicken Bursa and Thymus

We have evaluated by means of cytophotometric techniques the nuclear content in DNA, in total nucleic acids and in histone proteins and the nuclear volume of the thymic and bursal lymphocytes in adult chickens. We have also made the same determinations in the developing bursal follicles before and after hatching. The results indicate that cortical differ from medullary lymphocytes for all the parameters considered both in thymic lobules and bursal follicles. Furthermore these differences appear analogous in both the organs, independently from the fact that they produce precursors of T and B lymphocytes respectively. As concerns the developing bursal follicle, the lymphocytes show the characteristics of the adult medullary lymphocytes. At the hatching changes occur in the nuclear content of total nucleic acids and histones. This is probably related to the exposure to antigenic stimulation through the cloaca.