When sperm are released from the lower segment of the epididymis, they are packed very densely. Due to this fact, the gametes are unable to swim. Their movement instead involves the peristalsis of layers of muscle located within the vas deferens, the main duct that extends between the epididymis and the ejaculatory duct. Prior to reaching the ejaculatory duct, various fluids are added to the male gametes.

In order to localize a green fluorescent tag to filamentous actin in the sample of rat epididymis tissue presented in the digital image above, the specimen was labeled with Alexa Fluor 488 conjugated to phalloidin, a phallotoxin derived from the toxic death cap mushroom. Texas Red conjugated to the lectin wheat germ agglutinin, which selectively binds to N-acetylglucosamine and N-acetylneuraminic residues, was also applied to the tissue sample, as was the DNA probe Hoechst 33342. 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.