RED BLOOD CELL, SEM. RED BLOOD CELL SEM This highly enlarged scanning electron micrograph (SEM) depicted a closer look at the details exhibited by of number of red blood cells found enmeshed in a fibrinous matrix on the luminal surface of an indwelling vascular catheter, Magnified 11397x. In this instance, the indwelling catheter was a tube that was left in place creating a patent portal directly into a blood vessel. Note the biconcave cytomorphologic shape of each erythrocyte, which increa