Platelet response.

Young (6-12 weeks; ▵) and old (33-46 weeks; ▴) wild-type C57/Bl6 mouse platelet responses to administration of 5-FU (150 mg/kg) were compared. Elevation of platelet counts in old C57/Bl6 mice was much greater than in young mice. Data were derived from serial observations in groups of mice in 5 independent experiments (a total of 23 young and 55 old C57/Bl6 mice). During the initial 25-day observation period, there were 5 to 15 young and 8 to 43 old C57/Bl6 mice.