In situ hybridization for NP1, NP2, and NPR mRNAs in the retinal ganglion cell and inner nuclear layers of the retina. Transverse sections of rat eyes were hybridized with digoxigenin-labeled antisense cRNA probes to NP1 (A), NP2 (B), or NPR (C). D, Hematoxylin and eosin-stained section to reveal cell bodies and retinal layers. E, Sections were also incubated with NP1, NP2, and NPR sense probes. A representative section, with lack of specific signal, is shown here for the NP1 sense probe. F, Low-power image of NP1 mRNA localization, showing lack of a gradient for NP1 expression.