[1] Univ London, Dept Vet Basic Sci, Struct & Mot Lab, Royal Vet Coll, Hatfield AL9 9TA, Herts, England
[2] Univ Hull, Ctr Med Engn & Technol, Kingston Upon Hull HU6 7RX, N Humberside, England
[3] Univ Hull, Hull York Med Sch, Funct Morphol & Evolut Unit, Kingston Upon Hull HU6 7RX, N Humberside, England
[4] Univ York, Hull York Med Sch, Funct Morphol & Evolut Unit, York YO10 5DD, N Yorkshire, England