^ IPL 
Sections of a transgenic mouse retina expressing Pgalactosidase under control of a bovine rho- 
dopsin promoter. A: The jSgalactosidase substrate X-gal stains only the photoreceptors. B: Hema- 
toxylin and eosin staining shows the cell layers. 
From Zack, D.f., Bennett, f., Wang, Y., Davenport, C, Klaunberg, B., Gearhart,]., and Nathans, 
J. 1991. Neuron 6:187-199. 
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