Abnormal platelet morphology Abnormal dense tubular system 2013-11-29T09:35:44Z An anomaly of the intracellular membrane complexes known as the dense tubular system. UMLS:C4022881 The dense tubular system (DTS) functions to regulate platelet activation by sequestering or releasing calcium, similar to the sarcotubules of skeletal muscle. In resting platelets, the DTS exists as thin elongated membranes. Within 10 seconds of the addition of thrombin, platelets show a major ultrastructural change in their DTS: from the thin elongated form to a rounded vesicular form. HP:0012491