A comparative study on surface morphology of sperm and mature egg in three species flatfish.

The surface morphological structures of sperm and mature egg of three species flatfish Japanese flounder Paralichthys olivaceus,turbot Scophthalmus maximus L,and Verasper moseri were studied by scanning electron microscopy.Comparing results demonstrated that there are four obvious differences in sperm surface structures among three species flatfish,including the location of nucleus anterior pit,the shape of sperm head,the number of mitochondria in midpiece and length of the flagellum.But in the surface morphology of mature egg of three species flatfish,it is similar essentially among Japanese flounder and turbot,excepting stripe stars flounder.Four structure characteristics of the shell membrane are observed in V.moseri,they are a rough outer surface,various microspores in size,diameter as well as the most thick shell membrane(3.87±0.24) μm which is twice thicker than Japanses flounder and turbot and spiral pipe layer in micropyle only for 4-6 layers about half of Japanses Flounder and turbot.It was concluded that the difference was obvious in the surface morphology of sperm and mature egg between three species of Flatfish,and stripe stars flounder as genetic distance of the farthest Pleuronectidae fish,have significant level.