Final answer:
Around one-third, or 33%, of the platelet pool is stored in the spleen. This storage facilitates the body's clotting mechanism in response to blood vessel injury.
Step-by-step explanation:
Approximately one-third of the platelet pool is stored in the spleen. One-third expressed as a percentage is 33%. Therefore, the approximate percentage of platelets stored in the spleen is 33%. This correlates with platelets being part of the formed elements of the blood, which also includes erythrocytes and leukocytes. After circulating in the blood, a portion of platelets migrates to the spleen where they are stored until needed for clotting to limit blood loss.