Fig. 5. Physiological blepharoptosis in Egr3^-/- mice. Compared with wild-type mice (A), Egr3^-/- mice (A') have prominent blephoroptosis (drooping eyelids). (B) Whole-mount lacZ histochemistry of the inner eyelids from adult Egr3^+/+:DlZ⁺ mice showed dense sympathetic innervation to the superior and inferior tarsal muscles (black arrowheads) and Meibomian glands in the inner eyelids (columnar innervation, white arrowheads). (B') Sympathetic innervation was markedly decreased to the upper and lower eyelids (black arrowheads) and the Meibomian glands (white arrowheads) in Egr3^-/-:DlZ⁺mice. Compared with wild type (C), adult Egr3^-/- mice (C') developed corneal ulceration (arrow), most probably owing to impaired secretomotor function of the Meibomian glands. Scale bars: 0.5 mm. ^*nasal canthus.