Disparity of fibre size and density between PCS piglets and their normal litter mates. ST, LD and G muscles were removed from 4 sets of 2-day-old splayleg male piglets, each comprised an affected and a normal litter mate. Muscles were immunostained for dystroglycan, myosin heavy chain (MYH) slow and MYH fast. For each muscle sample, 6 microscopic fields were randomly selected for morphometric analysis. (A) Typical muscle fields of normal and PCS (ST muscles) immunostained for dystroglycan. PCS fibres were clearly smaller than those in the normal counterpart. (B) Fibre cross-sectional area was determined in PCS and normal muscles. PCS piglets showed smaller fibre size and higher fibre density in all three muscles. Differences between pair-wise combinations of the least square means were tested for significance (*p < 0.05). Asterisks indicated statistical significance between normal and PCS muscle. The error bars indicate standard error.