Fetal Research and Applications A Conference Summary (1994) / Chapter Skim
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Session II: Preembryo Research
Session II: Preembryo Research
Pages 15-25
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From page 15... ...
In experiments with a strain of mice, it was observed that the two classes of spermatozoa arising from meiosis were not equally successful in fertilizing eggs; one class fertilized 80 percent of the eggs. It was subsequently determined that this unexpected disparity results from differences in the way in which genetic information encoded in the ONA of one specific locus is transcribed in the two classes of spermatids.
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From page 16... ...
Governmental permission to conduct experiments with human fetal egg follicles has recently been granted in the United Kingdom, and experiments have been initiated to study ovarian growth and oocyte development. Permission has not yet been sought for fertilization of human fetal oocytes.
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From page 17... ...
Micromanipulation is a technology that employs very fine glass microtools attached to robot arms hooked to a microscope and moved by remote control (Figure 2~. In embryo studies in experimental animals, micromanipulation is used to extract cells or cell components for genetic analysis and diagnosis, to inject sperm into eggs, to transplant cell nuclei for genetic study, or to remove damaged tissue.
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From page 18... ...
(a~) The blastocyst is secured to the holding pipette close to the inner cell mass and held by gentle suction.
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From page 19... ...
One of these methods is called fluorescence in situ hybridization (FISH) in which complementary pieces of single-strand DNA with identified sequences are used to bind to single-strand DNA in the blastomere nucleus to identify specific sequences.
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From page 20... ...
This occurs at a time when, with techniques now available or being developed, answers to the major questions in reproductive biology are at our fingertips. OPEN DISCUSSION PERIOD All three presentations stimulated discussion concerning chromosomal abnormalities in fetuses and the dilemma of how research is to be pursued in this area if IVF embryos are kept solely for patients and oocyte fertilization is held in abeyance because of potential controversy.
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From page 21... ...
Regarding implantations of multiple embryos, a participant asked why, with the availability of cryopreservation for IVF embryos, this practice was still routine when it is well known that multiple births and their ensuing dangers (e.g., premature births, growth retardation, infant mortality, and personal burdens of triplets and quadruplets) are the common result.
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From page 22... ...
A participant involved in data collection in this area reported that given the differences in technical competence at IVF centers, microsurgical fertilization does not result in fetal malformation any more significantly than normal IVF. Preimplantation Genetic Analysis of Single Human Blastomeres MARK HUGHES Baylor College of Medicine, Houston, Texas Until recently, a couple who carries the gene for a genetic disease had three recourses: elect not to have children, adopt or use artificial insemination for recessive disorders, or terminate pregnancy if prenatal testing revealed the presence of disease in the unborn child.
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From page 23... ...
To date, hundreds of patients have inquired about preimplantation analysis at IVF centers all over the world. The molecular biological techniques involved in Reimplantation diagnosis require those doing the testing to have extensive training and experience.
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From page 24... ...
Because of limited access to human female gametes, studies are conducted mostly with laboratory animals, but human oocyte research will ultimately be needed to resolve these questions. Access to early human embryos is also critical for understanding fragile X syndrome, and possibly other diseases involving DNA repeats.
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From page 25... ...
An interesting comparison may emerge between IVF pregnancy rates of parents utilizing preimplantation genetic analysis, who have normal reproductive systems, and rates among the more common IVF parents who have reproductive difficulties. A persistent question concerning genetic analysis is confidentiality, for example, when an embryo is implanted that is known to be an unaffected carrier of genetic disease.
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