Nikon manufactures an object marker that screws into your objective receptacle on your microscope. This is a pretty cool tool for Cytologists and people who need to mark their specimens.
The object marker is used to identify specific areas on your slides.
The new object markers are self dotting, as opposed to the older style where you had to use the little wand and the foam inserts. This new object marker is much more efficient and easier to use. It can be refilled with ink from any of the major office supply stores like Staples or Office Depot.
Although, the object marker is made by Nikon, it fits most brands of scopes. (The Eclipse series requires an adapter). You can look at the following hyper link to see if the object marker is compatible with your microscope and obtain pricing information.