arrow and arrowhead - the only way to indicate two different cells? (Feb/13/2009 )

hi,

I have a picture of many cells stained with immunofluorescence method. I want to indicate two different cells on the picture by arrow and arrowhead....what other ways are there to indicate the two different cells?

I was thinking of having two arrows with different colors, but then I said to myself maybe the journals don't accept it that way.

You can use white and black arrow/arrowhead to label the two types of cells if both arrows stand out against the background. Arrow vs arrowhead of the same color is another choice.

I have seen one paper indicate with star (asterisk)