The method of the alternate culture and animal passage was introduced in the study of human glioma. For animal passage the hereditary asplenicathymic (lasat) mice were used as a carrier. Because the ...lasat mice have practically no cellular and only little humoral immunity, the rate of tumor take was expected to be raised, and successful results were obtained. Ultrastructural and immunohistochemical (GFA protein) studies were also done. The overgrowth of stromal elements in reculture of tumors in lasat mice was less vigorous than in athymic nude mice. After four passages through lasat mice, an established well differentiated cell nests, and this alternate culture and animal passage suggested to enhance the differentiation and growth capacity. After three passages through lasat mice, the tumor line, KNS-42-L, produced tumors also in athymic nude mice and their histological features were essentially the same as those in lasat mice, and hence the lasat mice could be saved.