Mechanism of platelet liberation.

Megakaryocytes from 5 patients and 1 normal person were observed electronmicroscopically. In some pathologic states platelets seemed to be liberated without demarcation membrane system (DMS) and in a normal individual they seemed to be liberated independently of DMS. These findings suggest that DMS is not concerned with platelet liberation and that platelets are liberated through pseudopodia and bleb formation. In mature megakaryocytes vigorous amoeboid movement seems to exist and both pseudopodia and blebs may represent this movement. Structural similarity between surface connected system (SCS) of platelet and DMS of megakaryocyte suggests that the structure called DMS is transported as SCS into platelet.