The effects of stains and investigators on assessment of morphology of canine spermatozoa

Percentage and types of morphological abnormalities found in canine spermatozoa were evaluated by three investigators using three stains (Giemsa-Wright stain [Diff-Quik], eosin Y/nigrosin [Hancock], and eosin B/nigrosin [Society for Theriogenology morphology stain] with conventional light microscopy, compared to phase contrast microscopy on unstained samples. The percentage of spermatozoa with abnormal heads, midpieces, and tails varied by technique and by investigator. Average percentages of morphologically normal spermatozoa were significantly higher in samples stained with Diff-Quik and samples examined by phase contrast microscopy than in samples stained with Hancock or Society for Theriogenology morphology stains. No effect of investigator on the percentage of morphologically normal spermatozoa was assessed. Results suggest that staining or preparation technique may alter the morphology of canine spermatozoa artifactually.