Fig. 1. Analysis of Fgf8a and Fgf8b in the isthmus by RT-PCR. (A) Part of the Fgf8b cDNA and amino acid sequence showing the difference between Fgf8a and Fgf8b. Fgf8a lacks the boxed region (Crossley and Martin, 1995; MacArthur et al., 1995a). The primer pair for RT-PCR are underlined, expected length of Fgf8a and Fgf8b being 202 and 235, respectively. (B) Quantitative RT-PCR. The number above each lane indicates the number of the cycles of PCR. Lane M is the DNA size marker of a 
x174/HincII digest. Analysis by NIH Image based on this figure indicated that amplification was logarithmic until cycle 40. RT-PCR analysis shows that Fgf8a and Fgf8b are localized in the isthmic region, Fgf8b being predominant. Other Fgf8 isoforms were not detected.
