I read one article while searching for AO staining, sending you may be useful.

Aniline blue staining

A drop of semen (swim-up sample) was spread on the glass

slides and allowed to air- dry. All the smears were fixed in

3% buffered glutaraldehyde for 30 min. The slides were then stained with 5% aqueous Aniline Blue and mixed with

4% acetic acid (PH 3.5) for 7 min. Three classes of head

staining intensities were noted, namely unstained (gray/

white), partially stained, and entire sperm head stained dark

blue.

Dear Kanchana

I wonder if you mean for human spermatozoa or other animals. As a general guide, you may find something useful thorough attached papers,

Good luck