Figure 4. Time course changes in the expression of EGF-like ligandgenes, Areg, Ereg and Btc at 0, 48 and 56 h after PMSG treatment and2, 4 and 8 h after hCG treatment. Data were expressed relative tomRNA expression in the ovaries before PMSG (=1.0). Different letters(a and b) indicate significant changes in the expression of each gene(p<0.05). Closed bar indicates at 56 h after PMSG injection withouthCG. n=5 in each group .