Fig. 18. The mouse cornea suggests that 5% to 10% of the cells in the cellular corneal stroma are actually one of three types of bone marrow-derived immune cells. The anterior one-third of the cellular corneal stroma contains professional (MHC-positive) dendritic antigen-presenting cells in periphery of the cornea, whereas nonprofessional (MHC-negative) dendritic cells are present in both the periphery and center of the anterior cornea. The posterior-most regions of the cellular corneal stroma appear to contain macrophages in the periphery and center of the cornea. (From Hamrah P, et al. The corneal stroma is endowed with a significant number of resident dendritic cells. Invest Ophthalmol Vis Sci 44:581, 2003.)