Summary
The in vitro effects of two anti-adhesive agents, designated as substances “86” and BLR-743, on the ultrastructure of rabbit blood platelets were examined. When compared with control platelet preparations, it was found that these agents, over a 10 min period, induced platelets to become spiny spheres. Vacuoles of the surface connected system inside platelets tended to enspherulate, also. No change in structure or location of form-maintaining structures such as microtubules were observed in treated platelets. Neither were changes observed in the structure or location of mitochondria. While the distribution within platelets of α-granules and vacuoles containing 5-hydroxytryptamine granules seemed to be little affected by treatement of platelets with these agents, 5-hydroxytryptamine granules were reduced in number and α-granules expressed variable degrees of electron density suggesting variable degrees of extraction of materials from these granules. It is concluded on the basis of the morphologic changes in platelets observed that the anti-adhesive agents have a primary action on the plasma membrane and other membrane bound structures of blood platelets.
