We analysed the expression of members of the hh gene family in adult ocular tissues of newt, frog and mouse by RT-PCR method. Shh displayed restricted expression in the neural retina that was conserved in each species analyzed. X-bhh, X-chh and mouse Ihh were detected in the iris and in the retinal pigment epithelium, while mouse Dhh was detected additionally in the neural retina and faintly in the cornea. We also found that two types of ptc genes, potential hh targets and receptors, were expressed in these tissues, suggesting the presence of active hh signalling there.
Takabatake, T., Ogawa, M., Takahashi, T. C., Mizuno, M., Okamoto, M., & Takeshima, K. (1997). Hedgehog and patched gene expression in adult ocular tissues. FEBS Letters, 410(2–3), 485–489. https://doi.org/10.1016/S0014-5793(97)00645-5