Why Are Red Muscle Fibers Red?
Why Are Red Muscle Fibers Red? This color difference is caused by a red pigment, myoglobin, in the sarcoplasm (cytoplasm) of muscle fibers. Hemoglobin, the pigment of red blood cells, brings oxygen to capillaries on the muscle fiber surface. From here, the transport of oxygen to the interior of the fiber is facilitated by myoglobin.