Red blood cells, T lymphocytes and activated platelets
Copyright 2009 Dennis Kunkel Microscopy, Inc.
Caption: Human blood - red blood cells, 3 T-lymphocytes and activated platelets. Human red blood cells are the most abundant type of cell in human blood, accounting for 40% of the blood volume. Each cubic millimeter of blood contains around five million of these tiny, flexible disc-shaped cells. The red color comes from the iron-containing protein hemoglobin, which picks up oxygen in the lungs and distributes it around the body. Because the cells have no nucleus and are subjected to constant physical action, they last only four months before being destroyed and broken down. T lymphocytes are involved in the specific immune response and are composed mainly of precursor T cells and B cells (pre-T cells and pre-B cells). Platelets are cell fragments in the blood that play an essential role in blood clotting and wound repair. Platelets can also activate certain immune responses. Magnification*: x800 Type: SEM
*(Magnifications are based on a 35mm slide image of 24mm in the narrow dimension.)