Scanning electron microscopic observations of the surface of the initial lesion in experimental streptococcal endocarditis in the rabbit.

The surfaces of vegetations in the first 24 h after initiation of experimental streptococcal endocarditis in rabbits were examined systematically using the scanning electron microscope (SEM). Most of the observed fields were occupied by amorphous material but with the SEM very small features of interest could be identified. Erythrocytes were more frequent before 6 h and leukocytes were rarely seen. Bacteria were significantly more frequent at 10/15 min and at 20 h. It is suggested that bacteria lodge on the vegetation surface following inoculation and that after a lag phase colonies are formed within the vegetation which reach the surface again at about 20 h.