Skeletal muscle contraction is instigated by signals from the nervous system and requires energy from adenosine triphosphate (ATP), which can be obtained from a number of bodily processes, such as glycolysis and oxidative phosphorylation. Most of the body’s skeletal muscles are arranged in pairs. This organization, in which each member of the pair pulls in the direction opposing the other member of the pair, allows the skeleton to be controlled with great precision. An example of paired skeletal muscles that function in this way are the biceps and triceps, which respectively flex and extend the forearm.

This widefield image of a rat skeletal muscle tissue section was produced by probing the specimen with Alexa Fluor 568, Oregon Green 488, and Hoechst 33342. The Alexa Fluor dye was conjugated to phalloidin, targeting the cytoskeletal F-actin network, and Oregon Green 488 was conjugated to WGA in order to localize a green fluorescent tag to the Golgi complex. The nuclear counterstain Hoechst 33342 was employed to visualize cell nuclei. Images were recorded in grayscale with a 12-bit digital camera coupled to a Nikon Eclipse 80i microscope equipped with bandpass emission fluorescence filter optical blocks. During the processing stage, individual image channels were pseudocolored with RGB values corresponding to each of the fluorophore emission spectral profiles.