Question

How are blood platelets formed?

Answer 1

Platelets are formed in the bone marrow by segmentation of the cytoplasm (the cell substance other than the nucleus) of cells known as megakaryocytes, the largest cells of the marrow. Within the marrow, the abundant granular cytoplasm of the megakaryocyte divides into many small segments that break off and are released as platelets into the circulating blood. After about 10 days in circulation, platelets are removed and destroyed.

Thus, blood platelets are not cells but are cellular fragments formed by cells called megakaryocytes.