The process of the ovary development and oogenesis in the cultured-pond Mugil cephalus

The biological character of ovary development and oogenesis in the artificial cultured grey mullet of outdoor pond was reported firstly. The analysis of ovary histological sections revealed that an ovary of thin line was seen in grey mullet after being cultured for three months, then, the oogonia of diplotene stage of the first meiotic prophase in ovary transformed into primary oocyte after being cultured for about five months. During this stage the germinal vesicle (nucleus) and cytoplasm increased in volume, but the nucleo-cytoplasmic ratio decreased from 3.5 : 1 to 2 : 1. The development of early oocytes in ovary stagnated until the third year of culture. At that time, the oocytes of adipose vesicle phase could be seen in the sections of ovary. The oocytes of vitellogenic phase occurred in the autumn of the third year . We have observed that under the artificial cultured condition of outdoor pond the ovary of grey mullet could not complete maturation and the oocytes only developed into the late stage of vitellogenesis, i. e, the cytoplasm of oocyte was full of yolk granules and germinal vesicle located at center without migration. These results will provide the important scientific basis for the artificial prepagation using cultured grey mullet. Finally, the biological character and physiological role of important cell organella in the oocytes of six phases in the process of oogenesis were discussed in the paper.