Establishment of Master Cell Stock and Working Cell Bankof MDCK Lines and Selection and Evaluation o

<正> Under the prerequisite that the incidence of cancer or tumor in negative-control nude mice inoculated subcutaneously with primary feline or canine kidney cell cultures purified in vitro at passage 3 was 0 (0/22) and 0 (0/10), respectively. The incidence of the progressively-growing malignant tumor(MT) in positive-control nude mice inoculated subcutaneously with Hela cell cultures of KB, X, or NM20/X strain was 10/ 10, 25/25 and 5/51, respectively. The results showed that the incidence of tumor in nude mice with di-and hy-perploid YB strain of MDCK cell during 17 - 23 passages, with hyper- and hypoploid KA strain of MDCK cell