An ink composition for marking a tissue specimen is provided. The ink composition has a general formula of 30.0 wt. % to 54.0 wt. % of an alkali soluble styrene； 0.3 wt. % to 1.7 wt. % ethyl hydroxyethyl cellulose； 8.0 wt. % to 35.0 wt. % colorant； 0.0 wt. % to 13.0 wt. % pigment； 23.0 wt. % to 47.0 wt. % deionized water； 0.35 wt. % to 1.65% defoamer and 0.1 wt. % to 1.1 wt. % preservative. The inks in accordance with the invention may have a peak transmission in the visible spectrum at a wavelength of from 322 nm to 716 nm or having a lineal UV-Vis spectrum with no visible peak transmission between 250 nm and 950 nm. When applied to a tissue specimen the ink compositions do not bleed onto adjacent tissue margins. When view under a microscope the color of the ink compositions can be distinguished from each other.
