번식생리 및 내분비 : 돼지 난포란의 성숙과 수정과정에서의 Cortical Granules 의 분포와 기능

Recent advances with in vitro maturation and in vitro fertilization have contributed to increase the availability of mammalian embryos for the production of clone or transgenic animal. In livestock animals, however, the incidence of polyspermy during in vitro fertilization is much higher than in vivo fertilization. It has been observed that cortical granule reaction, which is a major factor for the block to polyspermy, is take place abnormally in the in vitro matured and fertilized livestock animals. Cortical granules are membrane-bound organelles and are situated at the oocyte cortex. Following sperm penetration, cortical granules extrude their contents into the perivitelline space. Cortical granule contents released into the perivitelline space are thought to be responsible for block to polyspermy at the vitelline membraneand the zona pellucida. Cortical granule contents of these material are probably glycosylated materials, but the exact function is not known. In immatured oocytes, cortical granules are dispersed through the cytoplasm of oocytes and moved next to the plasma membrane during maturation. Recent studies showed that microfilaments, one of the major cytoskeletons, have responsibility for the centrifugal movement of cortical granules during maturation. It was also suggested that in the pig the abnormal cortical reaction in vitro fertilization maybe related to the factors) from oviductal fluid. In this review paper, we addressed the distribution and the role of cortical granules during maturation and fertilization in mammalian oocytes.