1. 1 Definition of stem cells Stem cells are cellls found in most multi-cellular organisms, which have the ability to renew themselves and differentiate into a diverse range of specialized cell types 干细胞:具有自我更新能力、并可分化产生某种(或多种) 特化细胞的原始细胞。4 Stem cells are cells found in most multi-cellular organisms, which have the ability to renew themselves and differentiate into a diverse range of specialized cell types. 1. 1 Definition of stem cells 干细胞：具有自我更新能力、并可分化产生某种（或多种） 特化细胞的原始细胞