Vital Staining of Earthworm Ovary

To mount and stain earthworm ovary using Janus green stain.

Materials

• Well-grown earthworm
• Dissection set
• Janus green stain
• Clean glass slide
  

Procedure
The earthworm is a hermaphrodite. A pair of ovaries is situated in its thirteenth segment. They are pyriform, semi-transparent, hanging freely into the coelom, and attached by their broad ends to the septum of the twelfth and thirteenth segments. Each ovary is a white, compact mass made up of finger-like processes. Each ovary contains ova in a linear series. Each ovum is large, with a distinct nucleus and nucleolus.

Take a full-size earthworm and open it dorsally. Cut the intestine, invert it, and ventrally below the heart the ovaries are seen as white dots. Pick them up carefully, with the help of a forcep, and place them on the glass slides. Use 2 drops of Janus green stain. Leave it for 5 minutes and observe under the microscope.