[Restoration and acceleration of the development of the capacity for antibody synthesis by the humoral factor of the thymus].

A fraction stimulating the antibody synthesis to sheep erythrocytes in administration during the neonatal period to mice and partially restoring the antibodygenesis in neonatally thymectomized rats was isolated from a calf thymus extract. Morpho-histochemical studies demonstrated a marked plasmocytic reaction in the spleen of neonatally thymectomized rats under the effect of the thymus extract fraction in response to immunization with sheep erythrocytes; however, there occurred no normalization of morphotopographic peculiarities of the splenic tissue, including the thymus-dependent regions. Administration of the extract was also not accompanied by any weight gain of the lymphoid organs, or increase in lymphocyte count in the peripheral blood and the count of splenic cells transforming into blasts under the effect of phytohemagglutinin.