It was discovered in this experiment that 3 days after inoculation of the ascitic fluid from P_(388) leukemic mice, the positive percentages of AcP and ?-Gase of the lymphocytes within the TNC of the recipients were increased significantly, while the positive percentage of ANAE was decreased. All the positive percentages of the three enzymes of the thymocytes within the thymus were increased significantly, but no abnormal structural changes were seen in the thymus. No histological and cytochemical changes were found in the lymph nodes and the spleen. Nine days after inoculation, the leukemia cell infiltration, hemorrhage and cell degeneration occurred in all the thymus, lymph nodes and spleen of the mouse. The normal structures of the organs were destroyed. The positive percentages of the cytochemical reactions of the three enzymes in the lymphocytes were all increased significantly. At this stage, TNC was very difficult to be isolated from the thymus. The results indicate that thymus and TNC may have a close relationship with the development of this type of leukemia.

This paper reports some histochemical,scanning and transmission electron mic-roscopical features of thymic nurse cell(TNC)of human fetuses.The results showedthat TNCs were all negative for ANAE,AcP,AlP,ATPase,5'-Nase and PAS.TNCcontained various numbers of lymphocytes.Some intracytoplasmic lymphocytes werepositive for ANAE,AcP,AlP and ATPase.Their ANAE positive percentage deter-mined were 26.8%.However,ANAE positive percentage of extracytoplasmic lym-phocytes of TNC were 51.3%.Our data demonstrated that there was significant dif-ference between these two ANAE positive percentages,P