Cellular aspects of in vitro fertilization (ultrastructural and cytogenetic studies of human gametes and zygotes).
After the birth of Louise Brown in 1978 as a result of the successful development of in vitro fertilization (IVF) techniques by Edwards and Steptoe, the use of this procedure has become extremely widespread, both in technologically advanced societies and even in countries that do not meet the minimal sanitary standards. In good hands, IVF techniques provide results slightly lower than those allowed by nature, that is about 20% of pregnancies. In other cases, the procedure may become a nightware coupled to a swindle, and even endanger the life of the hopeful mother-to-be. Even in the better prepared centers, with the highest rates of success, IVF is still surrounded by a myriad of problems that must be solved to optimize its results and to reduce the risk of zygotic loss and of multiple pregnancies. On the other hand, IVF offers unimagined possibilities for research on fields of such interest as the reasons for the high incidence of nidation and/or developmental failures of human zygotes, the high percentage of infertile or sterile couples, pre-implantation diagnosis and gene therapy. These problems will only be solved if research in human cell aggregates (also called pre-embryos) is allowed. The potential medical, human and social benefits of such research is considerable, and could have diagnostic and therapeutical applications in a short period of time. There are many possible causes of infertility or sterility: genetic, cellular, immunological, hormonal, developmental, etc. This volume includes the results of ultrastructural and cytogenetic studies of human gametes and zygotes, and tries to shed some light on the origin of IVF failures. The use of a murine model for the study of the first zygotic division has also provided data on possible mechanisms resulting in abnormal zygotes, like hormonal unbalance or gamete aging. The morphological and genetic characteristics of the sperm in the father, and the age of the gamete, the hormonal balance, the genetic endowment of the oocyte, and the induction of superovulation in the mother seem to be important factors both when in vitro fertilization does not take place or when abnormal zygotes are produced.
D000177:Acrosome / Q000502:physiology; D000818:Animals; D002869:Chromosome Aberrations / Q000209:etiology; D025063:Chromosome Disorders; D002875:Chromosomes / Q000648:ultrastructure; D006224:Cricetinae; D005260:Female; D005307:Fertilization in Vitro / Q000009:adverse effects; D006801:Humans; D007248:Infertility, Male / Q000628:therapy; D008297:Male; D008647:Mesocricetus; D009865:Oocytes / Q000648:ultrastructure; D010063:Ovum / Q000648:ultrastructure; D011247:Pregnancy; D012306:Risk; D013084:Sperm-Ovum Interactions; D013094:Spermatozoa / Q000648:ultrastructure; D015053:Zygote / Q000648:ultrastructure