Mountant-induced loss of Shorr-stained blue sperm tails.

It has been reported that Shorr staining provides additional morphological information on the motility of spermatozoa in semen, by distinguishing between red and blue flagella. With our routine methods (involving mounting slides) we were unable to confirm these observations. The presence of both red- and blue-coloured sperm tails in Shorr-stained semen smears was apparent, however, if slides were unmounted. Only a very weak association between blue flagellar staining and immotility was observed. Stating whether a mountant was used should be reported.