[Restoration of antibody synthesis by means of thymus extract in neonatally thymectomized animals]

One of the fractions of the thymus extract of a calf obtained by the authors restored the synthesis of antibodies to sheep erythrocytes in neonatally thymectomized mice and rats. Fractions isolated anologously from the tonsils and the lymph nodes failed to influence the antibody genesis. The data obtained are in favor of the endocrine function of the thymus of significance in the establishment and regulation of the immunological reactivity.