Table 1: The life spans of 2BS cells in CPDs, based on the actual number of cells harvested and seeded.
Time of transfer to special medium
Average PDs per week
Pine pollen (1 mg/L)
Pine pollen (2 mg/L)
Note. Cells were grown from PD30 in DMEM supplemented with pine pollen at 1 mg/L and 2 mg/L, respectively. The cultured cells were split in ratios of 1 : 2 or 1 : 4 when the confluence of the culture was reached 70–80%. CPDs (cumulative population doublings) were calculated as log2 (), where and were defined as the density of cells at the time of harvesting and seeding, respectively. The last culture was defined as the subculture that could not be confluent in 3 weeks. Data were obtained from three independent experiments (, versus I).