Three basic sections of the epididymis are generally identified: the caput (head), corpus (body), and cauda (tail). The diameter of the epididymis increases as it proceeds from the caput to the cauda region. Internally the epididymis is lined with columnar epithelial cells and prominent microvilli. Inflammation of the structure, known as epididymitis, may occur if an infection of the bladder or urethra spreads. Symptoms of epididymitis often include testicular pain and swelling, fever, and painful urination or intercourse.

In the digital image above, a rat epididymis tissue section is presented that was labeled with the fluorophore Texas Red 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 488 conjugated to phalloidin and Hoechst 33342, which target filamentous actin and nuclear 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.