Blood, 1953, Vol. 8, No. 7, pp. 587-597.
© 1953 American Society of Hematology, Inc.
Electron Microscopic Studies of the Action of Thrombin
on Blood Platelets
E. DE ROBERTIS M.D.1,
P. PASEYRO M.D.1, and
MAGDALENA REISSIG M.D.1
1 Instituto de Investigación de Ciencias Biológicas, Departamento de Ultraestructura Celular, Montevideo, Uruguay.
The action of thrombin on blood platelets has been studied under the electron
microscope. In control experiments with preparations treated with normal
plasma or Tyrode fluid, the normal structure of platelets in their different forms
of extension and flattening on the film has been observed.
Thrombin (Parke-Davis Co.) in concentrations of 25 and 50 units per ml. has
a lytic effect on platelets. The number of platelets affected by this treatment
increases in the period of 5 to 30 minutes.
Disintegration proceeds in the hyalomere from the periphery to the center
with the formation of long fibrillar processes constituted by microvesicles. These
processes resemble myelin figures. The granulomere turns into an amorphous
dense body which also undergoes lysis. The final residue of disintegration is
constituted by microvesicular material and dense amorphous bodies.
The purified bovine thrombin of Seegers has exactly the same action. The
lytic effect is observed with concentrations of thrombin as low as 2.5 units per
ml. The number of platelets undergoing disintegration increases proportionally
to the logarithm of the thrombin concentration. The probable role of thrombin
and the lysis of platelets in normal blood clotting is discussed.
Submitted on November 15, 1952
Accepted on February 16, 1953
