Alternative splicing of the bovine FN1 gene. (A) Schematic diagram of the domain structure of FN1, consisting of three repeating units, types I (red), II (green) and III (blue). Splicing can occur at two different type III repeats (EIIIB and EIIIA, dark blue) or at several locations within the IIICS region (yellow). (B) Positions of the primers for detection of the EIIIB splice variant. (C) Positions of the primers for detection of the EIIIA splice variant. (D) Positions of the primers for detection of the IIICS- and IIICS full length splice variant. Primers surrounding the alternative spliced regions (marked in red) enable the distinction between the long and short splice isoforms. The primers marked in green were used for specific amplification of the full-length isoforms and the boundary spanning primers, marked in yellow, were used for specific amplification of the short isoforms.