Fig. 3.
129.Lmx1bV265D/+ mutants are resistant to angle abnormalities whereas B6.Lmx1bV265D/+ mutants are susceptible. (A) Representative images of the iridocorneal angle region (H&E-stained sagittal sections) in 3-month-old mice. WT mice of both B6 and 129 backgrounds have normal open-angle morphology. Narrow iris processes (IP), are known to occur intermittently around the angle of WT mice without obstructing aqueous humor drainage. CB, ciliary body; SC, Schlemm's canal; black asterisks, trabecular meshwork. In mutant eyes, abnormalities, including severe iridocorneal adhesions (arrows) as well as absent (white asterisks) or hypomorphic SC and TM, are locally present within individual eyes (middle row) with different locations within the same eyes having open angles of normal morphology (bottom row). Scale bars: 200 μm. (B) B6 mutants have high angle scores (see Materials and Methods), indicating largely closed or malformed angles. Strain 129 mutants have less severely affected, largely open angles. Higher angle scores indicate a more severely and more extensively affected angle around its circumference. A score of 96 represents a severely abnormal angle at all locations, whereas an angle with a score of 0 is completely normal and open at all locations. The strain 129 median grade of 31 indicates that angles were open at most locations around the eye. It is established that a small incidence of developmental abnormalities occurs in B6 WT mice (see main text). Boxplots show interquartile range and median line. Mann–Whitney U-test; *P<0.01 (129 vs B6 mutants, P=0.0023; 129 WT vs mutant, P=0.0055; B6 WT vs mutant, P=0.0033). We examined five eyes from the strain 129 WT group, six eyes from the strain 129 mutant and B6 WT groups, and seven eyes from the B6 mutant group.