Studies On Fertilization Cytology Of Left-eyed Flounder (Paralichthys Olivaceus), Offspring Of Meitogynogenetic Left-eyed Flounder, Turbot (Psetta Maxima)

Series of processures of histological section are modified to establish a new programme to adapt to the characteristics of eggs of flounder. Cytological studies on fertilization of left-eyed flounder, offspring of meitogynogenetic left-eyed flounder, turbot has been made through the new programme of paraffin section. The chorion and micropyle of left-eyed flounder are observed by transmission electron microscope and scanning electronic microscope. The main results are shown as follows. The chorion of left-eyed flounder is very thin and has no distinct variation after fertilization. There is no cortical alveoli in the cortex of eggs. Only one male pronucleus is observed in one egg of flounder.The male and the female pronuclei contact with each other and form the nucleus of zygote, which divides into two daughter nuclei. It is sure that the pattern of the fertilization of flounder is monospermy. The whole processes of fertilization of flounder, such as sperm entering into egg, emergenc of the sperm aster, forming the male pronucleus, completing of the second polar-body and forming the female pronucleus, two pronuclei fusing and then dividing into two cells eventually are almost same as the processes of fetilization in the other teleost. The processes of fertilization and abilities of development of the offspring of meitogynogenetic flounder are the same as normal flounder. The speed of incubation which eggs of offspring of meitogynogenetic flounder are usually at is consistant with that of control flounder when eggs are incubated in the same temperature. The chorion of turbot has only one thin layer. There is no distinct change of chorion which is observed during fertilization. Unlike eggs of flounder, there are cortical alveoli in the cortex of eggs of turbot. The pattern of the fertilization of turbot is monospermy, which is similar with that of flounder. The processes of fertilization are generally belong to the type of other teleost, but incubation time turbot take is a little longer than that of flounde in the same temperature .