Why do red blood cells look paler in the central part of the cell when viewed under the microscope?
Red blood cells are thicker on the edges and thinner in the
center, consequently they look paler in the center when viewed
under a microscope. This somewhat odd cross-sectional shape is
beneficial to the cells and allows them to deform more easily to
pass through capillaries that have a narrower diameter than the
un-deformed red blood cell so that the cell can move through the
capillary delivering its load of oxygen and picking up the waste
CO2 from the cells along the capillary.