As a one of unsaturated fatty acid, polyunsaturated fatty acids (PUFAs) have multiple actions: as precursor of prostaglandins (PGs), steroid hormone synthesis and energy production in animal reproduction. PUFAs, which include omega-3 (n-3) and omega-6 (n-6), are derived from the diet and changed by diet, species, breed and season. The plasma membrane of spermatozoa in mammals contain various PUFAs. These composition of PUFAs regulate the membrane fluidity and cause lipid peroxidation via generation of reactive oxygen species (ROS). Induced lipid peroxidation by ROS decreased viability and motility of spermatozoa, and it is reduced by addition of antioxidant and low concentration of PUFAs. Because oocytes of animal have a high lipid components, process of oocyte maturation and embryo development are influenced by PUFAs. In in vitro study, oocyte maturation, embryo development, intracellular cAMP and MAPK activity were increased by treatment of n-3 α-linolenic acid (ALA) during maturation, whereas n-6 linoleic acid (LA) negatively influenced. Also, inhibition of fatty acid metabolism in oocyte influenced blastocyst formation of cattle. PGs are synthesized from PUFAs and various PUFAs influence PGs via regulation of PG-endoperoxide synthase (PTGS). Steroid hormone synthesis from cholesterol is regulated by expression of steroid acute regulator (StAR) protein and mRNA. Exogenous n-3 and n-6 PUFAs altered sex hormone in animal through stimulate or inhibit StAR activity. Because PUFAs altered PG and steroid hormone synthesis, follicular development was influenced by PUFAs. This effect of unsaturated fatty acid could provide information for improvement of reproductive ability in animals.

INTRODUCTION
 UNSATURATED FATTY ACIDS ANDSPERMATOZOA
 UNSATURATED FATTY ACID AND OOCYTEAND EMBRYO DEVELOPMENT
 UNSATURATED FATTY ACIDS ANDREPRODUCTIVE EVENTS
  Prostaglandin Synthesis
  Steroid Synthesis
  Follicle Development
 CONCLUSION
 REFERENCES

• Yong Hwangbo(College of Animal Life Sciences, Kangwon National University)
• Hwa-Young Kim(College of Animal Life Sciences, Kangwon National University)
• Yu-Rim Lee(College of Animal Life Sciences, Kangwon National University)
• Seung Tae Lee(College of Animal Life Sciences, Kangwon National University)
• EunSong Lee(College of Veterinary Medicine, Kangwon National University)
• Hee-Tae Cheong(College of Veterinary Medicine, Kangwon National University)
• Boo-Keun Yang(College of Animal Life Sciences, Kangwon National University)
• Choon-Keun Park(College of Animal Life Sciences, Kangwon National University) Corresponding author