TYPE-SPECIFIC CHANGES IN FIBER SIZE AND SATELLITE CELL ACTIVATION FOLLOWING MUSCLE DENERVATION IN 2 STRAINS OF TURKEY (MELEAGRIS-GALLOPAVO)

Morphological features and the chronology of muscle changes after dene rvation were studied over a 21 d period in 2 heavy (HW) and light-weig ht (LW) strains of 6-wk-old male turkeys. The atrophy of tibialis cran ialis, gastrocnemius lateralis and plantaris muscles was apparent at d 3 after denervation. By d 21 the weight of these muscles had reached 45-60 % of that of nondenervated contralateral muscle. Cellular lesion s, such as irregularities in mitochondrial distribution or coagulative necrosis with fragmentation and lysis associated with moderate infilt ration of inflammatory cells, were similar in both strains. Ten days a fter denervation, immunolabelling of a proliferating cell nuclear anti gen (PCNA) expressed during the G(1) and S phase of the cell cycle rev ealed satellite cell activation in denervated muscles. The number of s atellite cells activated at d 21 was markedly greater in the HW than L W strain. Morphometric analysis revealed that fast twitch (type II) fi bres were atrophied after denervation, whereas slow-twitch (type I) an d slow tonic (type III) fibres were hypertrophied from d 10. Hypertrop hy occurred more rapidly in the LW than HW strain.