Platelets derived from Scl^–/Δ mice are functional. (A) Tail skin bleed time analysis of mice of the indicated Scl genotypes. Horizontal bars denote the mean. (B) Washed platelets derived from mice of the indicated Scl genotypes were stimulated with 0.5 U/mL thrombin (arrow) and aggregation monitored as described under “Materials and methods.” Scale bars show the magnitude of change in light transmission due to platelet shape change. This trace is taken from 1 experiment representative of 3 independent experiments.