@article{oai:ir.kagoshima-u.ac.jp:00008053, author = {WADA, Seiji K.}, journal = {鹿児島大学水産学部紀要=Memoirs of Faculty of Fisheries Kagoshima University}, month = {2016-10-28}, note = {1. Rock oyster, Grassostrea echinata, and three species of pearl oyster, Pinctada fucata, P. maxima and Pteria penguin, were used as materials. 2. The discharged eggs of C. echinat and P. fucata are at the first maturation prophase. The eggs of these species obtained from the excised gonads, though they are underripe when stocked in the ovaries, can be rendered fertilizable before the nucleus shows any signs of breaking down. 3. The oyster eggs are progressively improved in fertilizability while kept standing in sea water. A similar situation has been obtained in P. fucata eggs if they are exposed to ammoniacal sea water. The pearl oyster eggs which have undergone the nuclear breakdown in plain sea water are not always fertilizable., 4. The eggs of Pinctada maxima and Pteria penguin which are obtainable from the excised gonads become mature if they are kept standing in ammoniacal sea water but not in plain sea water. The eggs of these forms are not rendered fertilizable until the beginning of the nuclear breakdown. 5. Relationships between the cortex maturation and the nuclear breakdown have been discussed. It has been postulated that these two phenomena, though very probably they are started by some identical reaction(s), are not linked with a strict cause-and-effect relation, but that each is accomplished through a divergent way in the later part. This view seems to be able to explain the known facts on a much simpler assumption as compared with the classic notion which implies the cortex maturation is induced by some substances liberated from the nucleus.}, pages = {1--8}, title = {Fertilizability of Crassostrea and Pinctada Eggs as Related to Germinal Vesicle Breakdown}, volume = {10}, year = {} }