Fig. 1.

Hedgehog gene expression in the developing rat eye by RT-PCR. A, In P4 ocular tissues,Shh and Ihh mRNAs were not detected in lens or sclera. Shh was detected in the retina and a minute quantity was detected in the RPE. Ihh was detected in RPE, and a minute quantity was detected in the retina.B, Shh was first detected in the developing retina at E16 and was detected at all stages of development examined and in the adult. C, The amount ofShh expressed in the retina was quantified using serial dilutions (0.3, 3, 30 pg) of in vitro transcribed full-length Shh RNA mixed with 3 μg of P10 rat brain RNA before RT-PCR. In all experiments, actin RT-PCR reactions served as normalization controls. Shh and Ihh PCR reactions were amplified for 26 cycles, and actin PCR reactions were amplified for 15 cycles. Amplification products were not observed when reverse transcriptase was omitted from the reactions. D,Ihh was first detected in the eye at E13 and expressed in the RPE at E18 and in all subsequent stages examined, including the adult.