Thymic cell from fetal mice at 17th-18th days and new born mice at age of 1.3.5.7.9.11.13.15.and 17 days cultured with KC-2000 only containing IL-2 are all capa- ble of proliferation.

• 胎鼠第17天和18天及生后第1、3、5、7、9、11、13、、15、、17天的鼠胸腺细胞,在不加胎牛血清,只加 IL-2的 KC_(2000)培养液中均能生长增殖,而且发育全过程中出现了两个增殖高峰;