The diaphragm is a partition of skeletal muscle and connective tissue that divides the chest cavity from the abdominal cavity in mammalian species. The breastbone and backbone serve as sites of diaphragm attachment as does a centralized aponeurotic tendon. Respiration is heavily dependent on the diaphragm, which is relaxed during exhalation and contracts during inhalation. When relaxed, the diaphragm is arched like a dome and is in close contact with the lungs and heart. In the contractile state, the partition moves downward, facilitating the expansion of the chest and reducing pressure inside of the cavity. In addition to its role in breathing, the diaphragm is involved in digestive processes and waste expulsion.

Since its proper functioning is critical for breathing, limitation of the movement of the diaphragm can be life threatening. The muscular partition may be adversely affected by hernia, paralysis, infection, abnormal development, or injury, among other problems. If the diaphragm is hit suddenly, it may spasm and make taking in air difficult for a short time. This occurrence is often described as having the wind knocked out of the body. For various reasons the diaphragm may experience repeated involuntary, a condition commonly known as hiccoughs or hiccups. Most cases of the hiccoughs cure themselves with time, but numerous home remedies are widely utilized to help speed up the process.

In the digital image above, a sample of rat diaphragm tissue is presented that was labeled with the fluorophore Oregon Green 488 conjugated to wheat germ agglutinin, a fluorescent lectin that selectively binds to sialic acid residues. Wheat germ agglutinin conjugates are often used as probes for the Golgi network in mammalian tissues and cells. The sample was also stained with Alexa Fluor 568 conjugated to phalloidin and Hoechst 33342, which target F-actin and DNA, respectively. 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.