Fig. 5.

Appearance of pupils of the wild-type (A), M₂−/− (B), M₃−/− (C), and M₂−/−M₃−/− (D) mice. The pupils of the M₂−/−M₃−/− mice (D) are smaller than those of the M₃−/− mice (C). Full mydriasis was achieved in the M₂−/−M₃−/− mouse after instillation of atropine solution (E). The pupils of the M₂−/− mice (B) are indistinguishable from those of the wild-type mice (A). Scale bars, 1 mm. F,G, Pupil diameter (mean ± SEM;n = 4–30) of the mutant mice, measured in a bright room (∼1000 lux). The M₂−/−M₃−/− mice have smaller pupils than the M₃−/− mice in both sexes.