Table 1.

Population doubling times of the Walvax-2 cells with and without being subjected to freezing

Passage number	Without being subjected to freezing	Reconstituted from the frozen state
	Population doubling time(h)	Cell origin	Population doubling time(h)
P 10	18–20	PCB,P6	18–20
P 20	29–31	MCB, P14	30–32
P25	30–32	WCB, P20	30–32
P32	38–40	The 28th passage from the WCB	39–41
P43	39–41	The 38th passage from the WCB	40–42
P55	55–60	The 48th passage from the WCB	57–62