Wet Mount Evaluation of Sperm

The use of phase contrast and differential interference contrast (DIC) microscopy enhances the observation of structural detail within a cell. Phase-contrast microscopy is more widely available to veterinarians than DIC microscopy due to the higher cost of the DIC equipment. Wet mount preparation, as used in phase-contrast and DIC microscopy, causes less physical damage to spermatozoa. This chapter discusses the processes involved in the preparation of a wet mount. It also provides a description of DIC microscopy and phase-contrast microscopy. Sperm morphology should be evaluated under 400× magnification or higher. If the sample is too concentrated, spermatozoa will overlie each other, making evaluation of morphology difficult. The sample should be appropriately diluted to allow examination of individual spermatozoa.