Preliminary findings in germinal vesicle transplantation of immature human oocytes.
Transplanting a germinal vesicle (GV) from an aged woman's oocyte into a younger ooplasm has been proposed as a possible way to reduce the incidence of oocyte aneuploidy which is considered to be responsible for age-related infertility. In this study, we have assessed the efficiency of each step involved in nuclear transplantation-specifically cell survival, nuclear-cytoplasmic reconstitution, and the capacity of the reconstituted oocytes for in-vitro maturation. In addition, we have evaluated the fertilizability and karyotypic status of the manipulated oocytes by intracytoplasmic sperm injection (ICSI) and fluorescent in-situ hybridization technique respectively. Nuclear transplantation was accomplished with an overall efficiency of 73%. Due to the limited availability of materials, most nuclear transplantation procedures were performed between sibling oocytes. The maturation rate of 62% following reconstitution was comparable with that of control oocytes, as was the incidence of aneuploidy among the reconstituted oocytes. The ICSI results of the reconstituted oocytes yielded a survival rate of 77%, a fertilization rate of 52%, and a satisfactory early embryonic cleavage. Furthermore, in a limited number of observations where the nucleus of an aged oocyte was transferred into a younger ooplasm, there was an appropriate chromosomal segregation. These findings demonstrate that human oocytes reconstituted with GV nuclei are able to undergo maturation, fertilization, and early embryo cleavage, and maintain a normal ploidy. Although in-vitro maturation seems to be a limiting step, this technique would allow us to investigate further the nuclear-ooplasmic relationship during meiotic maturation.
The Center for Reproductive Medicine and Infertility, Weill Medical College of Cornell University, New York, USA.
T
T
Takeuchi
J
J
Gong
L L
LL
Veeck
Z
Z
Rosenwaks
G D
GD
Palermo
D000328:Adult; D002470:Cell Survival; D002478:Cells, Cultured; D022082:Cellular Structures / Q000637:transplantation*; D003582:Cytogenetics / Q000379:methods; D004622:Embryo, Mammalian / Q000502:physiology; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D007621:Karyotyping; D008297:Male; D008423:Maternal Age; D009865:Oocytes / Q000166:cytology* / Q000502:physiology*; D020554:Sperm Injections, Intracytoplasmic