アワビ精子先体反応における先体部膜系の変化

概要

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Focusing on the membrane events associated with the acroseme reaction, membrane fusion occurs between the plasma and outer acrosomal membranes, resulting in opening of the acrosomal apex to release the acrosomal contents. This is immediately followed by rapid extension of the inner acrosomal membrane into the acrosomal process membrane. These changes in the membrane structures were studied by freeze-fracture replica technique in connection with the distribution of intramembrane particles (IMPs) and of membrane sterols (FSCs). IMPs with an average diameter of 10nm are preferentially located on the P face of the plasma membrane in the acrosomal apex, including the trigger region. The initial change of the acrosome reaction is clearance of the IMPs from this apical region, while FSCs become to be densely distributed on the plasma and outer acrosomal membranes in the periphery of the acrosomal opening. As the acrosomal process elongates, IMPs which have been densely packed in a lattice-like pattern on the P face of the inner acrosomal membrane change to a loose lattice or a rhombic pattern with patches of particle-free areas. These IMP-free areas are found to be displaced by FSCs. Possible roles of the changes in the membrane composition concerning IMPs and FSCs during the acrosome reaction of abalone spermatozoa were discussed.
和洋女子大学の論文