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| home : pages : what's new in medicine vol. 4 : donor egg banks now a possibility ... : | |||||
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DONOR EGG BANKS NOW A POSSIBILITYDr.Eleonora Porcu, Director of Infertility and I.V F. Center at the University of Bologna in Italy, achieved the first success using frozen oocytes with the birth of a baby girl on February 16, 1997. Since then, seven additional pregnancies have been achieved .The Italian team first used frozen oocytes and ICSI almost by accident, according to Dr. Porcu's account of the case in Fertility and Sterility Journal 1997; 68 :724-726 . A 28 year old woman with a ten year history of tubal infertility had undergone egg retrieval in preparation for in vitro fertilization, but her husband could not produce the semen sample. Dr. Porcu decided to freeze the woman's eggs, and four months later they were thawed and micro injected with sperm. After a normal pregnancy, the woman delivered a healthy girl at 38 weeks gestation. The Italian researchers say that the team had recently achieved a world first birth resulting from micro injection of the frozen sperm and frozen egg at the end of October. Dr Porcu attributes her teams success to three factors. Since earlier research showed that cryo preservation can damage oocytes, the Bologna clinician tinkered with the concentration of cryo protectant used during the freezing procedure. The Italian team always uses ICSI because it overcomes frozen eggs' sluggish fertilization rate, according to Dr. Porcu. Freezing can damage the cytoplasmic membrane and zona pellucida (the membrane that surrounds the egg). This can prevent sperm from fertilizing the egg, and using ICSI, we have the same rate of fertilization as with fresh oocytes . In addition, the Bologna team uses Estradiol and Progesterone to prepare the lining inside the uterus for implantation. When you retrieve oocytes after gonadotrophin stimulation, you can reach high hormone levels . Dr. Porcu explained this can derange the endometrium so it's not ready for implantation. If you wait another cycle, and prepare endometrium (lining inside the uterus) with estrogen and progesterone, (like in the case of adopted oocytes), you will have more chance for implantation. Oocytes can be kept in liquid nitrogen for a year or longer. Immature eggs can survive over twice that of mature eggs, according to Dr.Tucker, of the Biology Association in Atlanta . In his experience the survival rate was over 60%. Freezing immature eggs involves less potential damage to chromosomes. In mature eggs there is more chance of damage during the freeze/ thaw, according to Dr. Tucker. You actually can freeze all ovarian tissue or any immature egg harvested . There are some womenwho might want to take advantage when they are younger to bank their eggs for the future . Freezing eggs will allow clinicians to develop donor egg banks . --> return to menu / back ... (click) --> return to top of the page (click) |
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