To examine sperm morphology, prepare at least two smears after the semen has liquified (>30 minutes). The specimen should be thoroughly mixed before pipetting the aliquot onto the slide and then mixed again before preparing the second slide. If the sample is undiluted, the technique that is used is the same technique used to make a peripheral blood smear or bone marrow smear (wedge smear technique). The wedge smear technique is demonstrated using a blood sample in this video. It is important that the well-mixed semen sample is spread at a proper thickness on the slide to allow clear viewing of individual sperm; too many sperm per slide makes evaluation difficult. However, too few, makes it hard to find enough sperm for an adequate evaluation. The smears are then labeled, air-dried, fixed, and stained.
Some of the more commonly used stains include:
- Papanicolaou (PAP) stain
- Differential Quik Stain Kit (Modified Giemsa)
- Shorr stain
Details of these staining methods are available in the WHO 5th edition.