Fine structure of the gametes and spermiogenesis in Spiophanes uschakowi (Annelida: Spionidae) from the Sea of Japan, with comments on fertilization biology in broadcast-spawning spionids
Keywords: پاکت تخم مرغ; Oocyte; Egg envelope; Cortical alveoli; Sperm; Acrosome formation; Fertilization mechanism; Ultrastructure; Polychaete;