Cryopreservation and its problems

Psychological study of in vitro fertilization-embryo transfer participants' attitudes toward the destiny of their supernumerary embryos

OBJECTIVE

To study the motivations underlying IVF-ET participants' choice to donate or destroy their supernumerary embryos.

DESIGN

Couples' opinions are studied through a questionnaire and a psychological interview.

PARTICIPANTS

Two hundred couples about to undergo IVF-ET.

SETTING

The fertility unit of an academic hospital.

MAIN OUTCOME MEASURES

Couples' choice for supernumerary embryos' destiny; opinions on embryo status, on importance of genetic lineage in the filial bonding, on gamete donation, and on multiple pregnancy risk.

RESULTS

Donation is the most frequent choice but destruction is tolerated by almost all the couples (92%). Couples considering the embryo as a child choose destruction as frequently as donation but refuse experimentation on the embryo. Donation is highest among couples who stress education more than genetic lineage in parental bonding. This is confirmed by the choice of the couples requiring donor gametes. Couples express differing attitudes toward risks of twins and risks of triplets: twins are much more desired than triplets, which are frequently refused.

CONCLUSIONS

Couples' opinions on the respective importance of genetic lineage and education in defining parental bonding are more determinant in their decision to destroy or to donate their supernumerary embryos than their opinions on the in vitro embryo status, which only determines their attitude toward experimentation.

Cytogenetic, cellular, and developmental consequences of cryopreservation of immature and mature mouse and human oocytes

This study examined the effects of cryopreservation on cellular organization, chromosomal complement, and developmental potential of immature and mature mouse and human oocytes. Chromosomal analyses were performed by DNA fluorescence microscopy and karyotyping on the same metaphase II-stage oocytes before and after freezing. Cellular analyses involved electron microscopy, time-lapse video recording, and fluorescent-probe microscopy of cortical granules. The findings demonstrate that while profound cytoplasmic, nuclear, and nucleolar alterations occur in the immature oocyte during cryopreservation, an apparently normal nucleus and cytoplasm is re-established progressively after thawing and culture. The resulting oocytes mature at high frequency and for the mouse, are fertilizable and capable of normal preimplantation of embryogenesis. Cryopreservation of mature mouse and human oocytes is not accompanied by a significant increase in the frequency of aneuploidy. However, cryopreserved human oocytes, while fertilizable, arrest development during the early cleavage stages and display aberrant patterns of cytokinesis. The possible etiologies of developmental failure in the human embryo that may be related to oocyte cryopreservation, as well as the potential benefits of cryopreservation of the immature oocyte, are discussed with respect to clinical and commercial applications.