Semen Stains

Nigrosin-Eosin (Hancock) Stain

There are a number of variations of the Nigrosin-Eosin stain. A commonly-used formulation is prepared as follows:

Dissolve in water:

• 5% w/v nigrosin
• 0.6% w/v eosin
• 3% w/v sodium citrate, dihydrate (to obtain physiologic osmolarity)

Adjust the pH of the stain to 7.0 by adding a few drops of 0.1 M NaH₂PO₄ or 0.1 M Na₂HPO₄ and filter through filter paper.