Ultrastructural studies of platelets of von Willebrand and normal swine.

Platelets from normal pigs and pigs with von Willebrand's disease were studied by ultrastructural and scanning electron microscopy. The majority of resting platelets were discoid or abortive-dendritic in gross morphology with an average size of 2.6 micrometer. The number of alpha-granules per platelet section was varied; however, a highly significant positive association was found between platelet size and the number of alpha-granules. These studies characterize porcine platelets more definitively and clearly establish the similarities between platelets from normal and those from von Willebrand pigs.