Physiological function of hyaluronan in mammalian oocyte maturation

Despite its structural simplicity, hyaluronan exhibits a broad spectrum of biological activities. Cumulus expansion observed during oocyte maturation in mammals is also induced by hyaluronan accumulation in cumulus−oocyte complexes. It has been demonstrated that this volumetric change in cumulus−oocyte complexes correlates with the progression of oocyte maturation. We have investigated the molecular mechanism of oocyte maturation in mammals, focusing on hyaluronan accumulation in cumulus−oocyte complexes during cumulus expansion. In this review, we describe the physiological function of hyaluronan, emphasizing the progression of oocyte maturation in mammals based on our previous findings.