Normal iridocorneal angles in strains with high and low IOP. The iridocorneal angle that contains the aqueous humor drainage structures (Schlemm's canal (SC) and trabecular meshwork (TM) had a normal morphology in strains CBA/CaJ (A, high IOP), BALB/cJ (B, low IOP) and all other strains. Pigment filled macrophages that resemble human clump cells were often located in the angle of CBA/CaJ mice but were never sufficient to block drainage. We have observed similar quantities of these cells at this location in other strains with lower IOP. The angle recess between the cornea (C) and iris root (I) was open and not occluded. Aqueous humor passes through this recess before entering the drainage structures. Original Magnification 630X.