Labeled [3H]thymidine incorporation into DNA in myoblasts derived from breast muscle of embryos (a) and chicks (b) subjected to TM at 39.5°C and 65% RH for 12 or 24 h/d (12H and 24H, respectively) from 180 to 408 of h incubation, and of control embryos/chicks incubated at 37.8°C and 56% RH until hatching. Different letters indicate significant differences (P ≤ 0.05) between treatments