Figure 2.

Schematic representation of peroxisomal regulation during folliculogenesis. Folliculogenesis is initiated with primordial follicles, which develop into primary follicles, secondary follicles, tertiary follicles, and finally preovulatory follicles. Under an LH surge triggered by oestrogen positive feedback, ovulation occurs for fertilization. This consecutive and synchronized event is accompanied by peroxisomal regulation to maintain the ROS balance and ensure the β-oxidation reaction. The peroxisomal marker enzyme catalase and peroxisomal biogenesis factor are induced during follicular maturation, whereas SODs are downregulated. A suitable concentration of ROS during different stages of the follicular phase is fundamental for ensuring oocyte development and ovulation. In addition to antioxidation, the peroxisomal β-oxidative enzymes ABCD3 and MFP2 are induced during follicular maturation and provide sufficient ATP and nutrition for oocyte growth, the selection of dominant oocytes, and the degradation of excessive lipid toxicity to maintain the efficiency of fertilization. The up arrow means “upregulation” while the down arrow stands for “downregulation.”