Individual megakaryocytic colonies.

Photomicrographs from healthy volunteers (A, 30 ×; B, 480 ×); 2°T (C, 30 ×; D, 480 ×), and ET (E, 30 ×; F, 480 ×) patients. (G) A healthy megakaryocytic colony composed of 3 megakaryocytes (480 ×).