The mRNA expression of MMP-2, MMP-9, TIMP-2, and TIMP-3 in the ovaries of normal and miniature pigs is shown in Fig. 1. The expression of MMP-9, which promotes follicle development by regulating FSH, was higher in normal pigs than in miniature pigs. On the other hand, the level of TIMP-3 mRNA (MMP-9 inhibiting factor) in the ovaries was higher for miniature pigs than for normal pigs. The expression of MMP-2 mRNA was more in the ovaries of miniature pigs, whereas that of TIMP-2 mRNA was higher in normal pigs.