Assisted reproductive technologies: contracts, consents, and controversies.
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Embryo donation programs and policies in North America: survey results and implications for health and mental health professionals.
OBJECTIVE: To use survey results from Society of Assisted Reproductive Technology to describe program policies regarding embryo donation, report protocols used for the disposition of cryopreserved embryos, and discuss clarification of guidelines governing ethical and psychosocially informed embryo donation. METHOD(S): A 66-item questionnaire was sent to the 312 Society of Assisted Reproductive Technology programs, generating 108 responses. RESULT(S): Seventy-eight (72%) of 108 programs offer embryo donation. Forty (37%) have actually performed donation, with 246 cycles completed and 53 "take-home babies." Disposition agreements for donors address divorce (92%) and death (90%). Only 28% require that potential donors undergo psychologic evaluation. Ninety-five percent of programs do not compensate donors. Seventy-one percent require a complete medical and psychologic history and 10% require genetic karyotyping. Three percent limit the number of donations. Eligible recipients include married couples (100%), unmarried couples (61%), lesbian couples (55%), and single women (59%). Sixty-four percent of programs require psychologic screening. Storage limits range from 2-10 years. Forty-nine percent of programs have unclaimed embryos in storage. CONCLUSION(S): Embryo donation is more often contemplated than performed. Variability in program procedures and policies suggests that guidelines need to be clarified. The complexity of the psychosocial and ethical issues underscores the importance of a routine, comprehensive psychologic assessment.
Female↗
Resolving disputes over frozen embryos.
The relation between respect for family and reproductive choice and use of IVF technology is in dispute in recent legal cases on the disposition of frozen embryos. Couples in IVF programs should be encouraged to stipulate in advance binding instructions regarding the disposition of such embryos.
Beginning of Human Life↗
The validity of contracts to dispose of frozen embryos.
The widespread abandonment of frozen embryos by the gamete providers or intentional parents urgently demands a solution. Most centres react by requiring patients to enter a prior agreement governing the future disposition of their embryos in all foreseeable circumstances. These dispositional directives are inappropriate and self defeating in the event of contingencies in which the patients remain competent to execute an updated directive. Internal and external changes may invalidate the prior directive by altering the situation as represented by the couple at the initiation of treatment to such an extent that it no longer corresponds with the actual situation at the time of the execution of the disposition. The prior agreement should only be considered binding if the agreement among the partners on a specific option was a material condition for one of the partners to start treatment.
Advance Directives↗
The disposition of carbaryl in the hepatopancreas, haemolymph and embryos of the viviparous scorpion, Heterometrus fulvipes (Koch) during gestation.
1. The disposition of carbaryl in the hepatopancreas and haemolymph of maternal animals and embryos of H. fulvipes (scorpion) after administration of a single sublethal dose was studied by g.l.c. 2. High levels of carbaryl were observed in haemolymph at 10 min, and in hepatopancreas at 1 h after administration. About 90% of the residues in the hepatopancreas were eliminated by 24 h. 3. In embryos high levels were noticed 6 h after administration and only 60% of the accumulated carbaryl was eliminated by 24 h. Carbaryl residues were observed in embryos even 1 week after administration.
Animals↗
Donation of frozen embryos after in vitro fertilization is uncommon.
OBJECTIVE: To determine the availability of donated cryopreserved embryos. DESIGN: Retrospective review. SETTING: Community hospital-based IVF-ET program. PATIENTS: Eighty-three consecutive infertile couples who had 98 sets of embryos cryopreserved after IVF-ET and GIFT between January 1, 1989 and December 31, 1991. INTERVENTION(S): Cryopreservation of fertilized oocytes or cleaving embryos after IVF-ET and GIFT. MAIN OUTCOME MEASURE(S): Disposition of frozen embryos as of December 31, 1995. RESULT(S): Of 98 sets of frozen embryos, 71 (72.4%) were thawed for transfer into the infertile woman. At an average of 6 years since the treatment cycle, six sets of embryos (6.1%) remain in storage. Of 21 sets of embryos not thawed for autologous transfer, the majority (17.4%) were discarded, leaving only four clutches (4.1%) available for donation. CONCLUSION(S): Couples who did not use their frozen embryos after IVF-ET and GIFT were four times more likely to destroy them than to donate them.
Cryopreservation↗
Disposition of chemicals in the developing embryo and fetus.
The uptake of foreign compounds and their distribution in the embryo and fetus at different stages of gestation are reviewed. In particular studies performed by means of autoradiography are discussed. It is shown that a number of compounds may be almost completely blocked by the placental structures early in gestation, although they are foreign compounds. In late gestation often one or a few organs may accumulate a particular compound; this may be due to metabolism, affinity for tissue components, etc. In some cases the site of accumulation of tissue binding of a drug has correlated well with the teratogenic or carcinogenic effects.
Adrenal Glands↗
The legal status of the embryo in comparative perspective.
Almost all decisions with regard to allowing or forbidding research with and on the embryo as well as any other diagnostic invasion into the embryo depend on what kind and range of protection human life in this early stage of its development is or should be entitled to. This question is commonly referred to as that of the 'moral status' of the embryo or-with special regard to legal provisions and sanctions-as its 'legal status'. The answer to this fundamental question, however, is much debated and highly controversial, both nationally and internationally. Therefore professional and legal regulations range from the rather permissive (as in the new English Human Fertilization and Embryology Act of 1990) on the one hand to the total prohibition of embryo research or certain reproductive procedures on the other (as has recently been enacted by the German Embryo Protection Act of 1990). Thus, trying to reach consensus with regard to an embryo's legal/ethical right to protection is made all the more difficult because such an opinion is often, consciously or unconsciously, prejudiced by the desire to give researchers either more or less freedom of action, depending on one's point of view: Those who wish to see diagnostic or other experimental procedures with embryos facilitated, are inclined to deny their human quality from the very start. They base their arguments on the lack of individual personality in the preinidation phase of development, or simply on the fact that in many countries abortion is not illegal at that stage. Those who, on the contrary, find abortion as well as embryo research indefensible, believe their position well-founded by assuming that the embryo, from the time of fertilization, has the individuality and personality of a human being and thus is entitled to its own basic legal rights. Since to me neither of these extreme positions seems to be particularly cogent, I will try in this article to show the reasons for and consequences of adopting a middle course which neither leaves the embryo at free disposition nor bars any kind of diagnostic or other scientific invasion.
Abortion, Legal↗
[Drug effects on embryo and fetus. 2. Diaplacental transport of drugs].
Drugs administered in pregnancy have primarily as their target the mother, and the embryo or fetus is an unwanted recipient. Only in a few cases therapy of the growing child via the mother is intended. Thus the knowledge of the risk-benefit ratios of various drug regimens during pregnancy is a matter of utmost concern to each physician. Experimental and clinical data show that there is no direct relationship between the chemical structure, the pharmacological activity or the toxicity of a drug in the adult and its specific action on the embryo. Nevertheless, the considerations presently known to be involved in determining whether a drug will be teratogenic and toxic or not mainly depend upon the type of drug, duration of dosage, access to the conceptus, developmental embryonic stage at time of dosage, disposition within the fetus and individual susceptibility. We have attempted to summarize the present knowledge concerning drug disposition in the embryo and fetus. In addition, based upon the mathematical evaluation of some new experimental results the pharmacokinetics of diaplacental drug transfer is demonstrated.
Biotransformation↗
Pharmacokinetics of 2-methoxyethanol and 2-methoxyacetic acid in the pregnant mouse: a physiologically based mathematical model.
A physiologically based pharmacokinetic (PBPK) model was created to describe the disposition of 2-methoxyethanol (2-ME) and its teratogenic metabolite, 2-methoxyacetic acid (2-MAA), in the pregnant CD-1 mouse. The model's foundation is a mathematical description of the physiological changes that occur during gestation (O'Flaherty et al., Toxicol. Appl. Pharmacol. 112, 245-256, 1992). The PBPK model was developed and validated with data collected on Gestation Day (GD) 11. Absorption, distribution, and oxidation of 2-ME to 2-MAA and ethylene glycol (EG) were simulated. Flow-limited disposition of 2-ME in maternal tissues was described using in vitro-determined tissue partition coefficients (PCs). The maximum velocity (Vmax) of 2-ME oxidation to 2-MAA was calculated from literature-based in vitro data. Vmax for EG formation, and Michaelis constants for 2-MAA and EG pathways, were estimated from optimized simulations of plasma 2-ME and metabolite levels obtained after intravenous injection of 5-600 mg 2-ME.kg-1.2-MAA disposition and elimination in the dam were described by a nonphysiological one-compartment model, which was linked to the 2-ME model, based on the volume of distribution (0.510 liters.kg-1) and overall elimination rate constant (0.124 hr-1) calculated from iv 2-MAA plasma concentration-time courses. Transfer of 2-MAA between the placenta and conceptus was described as a diffusion-limited process to more accurately simulate the higher concentrations of 2-MAA determined in embryonic compartments compared with maternal plasma levels. Subsequent 2-MAA disposition within the embryo proper and surrounding fluid of the GD 11 conceptus was adequately described using embryo/blood (0.94) and extraembryonic fluid/blood (1.33) PCs. Extension of the PBPK model to oral and subcutaneous 2-ME administrations required optimization of first-order absorption rates; model simulations agreed closely with measured 2-ME/2-MAA levels. With refinements and further validation, the PBPK model of 2-ME/2-MAA disposition should prove helpful for extrapolation throughout gestation and between species.
Acetates↗
[Legal issues in relation to cryopreservation of human gametes and embryos].
The article discusses the legal status of human gametes and embryos produced by in vitro fertilization. The author concludes that sperm, ova and embryos are not part of the estate of the procreators. However, the originators of gametes and embryos are granted the full disposition on their germ cells and the embryos resulting thereof.
Child Custody↗
The technology, law, and ethics of in vitro fertilization, gamete donation, and surrogate motherhood.
This article examines some of the legal, ethical, and policy issues raised by the development and use of technologies for noncoital reproduction: gamete transfer and manipulation, in vitro fertilization, and zygote transfer and manipulation. After briefly describing these technologies, this article examines three closely related concerns raised by their introduction: (1) the effect of new technologies on the social understanding of parenthood and the legal regulation of the family; (2) the impact on women and children of a market in the material and services for producing children; and (3) the rights and interests involved in conflicts over the control and disposition of extrauterine embryos.
Embryo, Mammalian↗
The passage of Florida's Statute on Assisted Reproductive Technology.
Until 1993, there were no statutes in the United States covering gestational surrogacy contracts, disposition of stored embryos and gametes, parentage of children born from donated gametes and embryos, and the inheritance rights of cryopreserved embryos of deceased donors. In March 1993, the Florida Assisted Reproductive Technology Act was passed to address some of these issues and to minimize the expense and emotional cost of related courtroom proceedings. Authors of the bill believed that motherhood of a newborn in the eyes of the law should be determined by two factors: genetic inheritance and the original intent of the woman to become the parent of record. The bill included the assumption that, in the cases of children born of gestational surrogacy, the commissioning genetic parents would be the "natural parents" of the child. Some of the reasons for legislative success of the statute include: 1) clear need for statutory guidance in cases involving reproductive technology, 2) relevance of the issue to cost containment (ie, judicial costs) in an era of health care reform, 3) careful use of scientific terminology and the support of the medical community, 4) involvement of a skilled legislative team, 5) participation of physician specialists in the development of the bill (ie, practicing gynecologists in assisted reproductive technology programs), 6) participation of the State of Florida legislative staff, and 7) consultation with appropriate lobbying groups (eg, Florida Catholic Conference). The successful legislative process that was followed to achieve passage of this bill can serve as an example for other states to emulate.
Female↗
[Anatomic and morphological studies on the initiation of somatic embryos obtained from meristematic apexes of Musa sp.
The origin of somatic embryos obtained from meristematic apexes of the Musa (AAA) clone "Gran enano" was analyzed through histological and morphological studies during the various development phases of the process. The research point out that somatic embryos developed directly from perivascular parenchyma cells of the leaves. Histological sections of globular embryos showed a radial disposition to cell and the existence of an epidermal layer that surrounds the embryo completely. When citocinine (Z or BA) was added, some embryos remained in globular stage with mild signs of enlargement but with no later development of invagination. Other's embryos reached the invagination stage; and some reached the enlargement stage with active photosynthetic tissues. However there were no to generation of complete plant regardless of additional treatment, such as "osmotic shock" or the additions of GA3--At present do not have an explanations for this results. Therefore, additional experiment should be in early, intermediate and later stages of somatic embryogenesis, in order to understand the mechanisms underlying the lack of development of plants from somatics embryos.
Cloning, Organism↗
The disposition of early-generated neurons in the rat embryo predicts the pattern of major axonal tracts.
During embryogenesis, the fiber tracts grow in a highly stereotyped pattern. A very small number of predetermined paths, preceding the growth of fasciculi, are present in the young neural tube (10-12, 15). What is the origin of these substrate pathways defined by Katz et al. (16) as "... a set of similar guidance cues which are aligned in a continuous discrete pathway..."? Could the first neurons play a role in the guidance of early nerve fibers? Observations in the brain stem revealed the presence of two longitudinal columns of early-generated neurons. These longitudinal columns were associated with well-differentiated marginal zones, characterized by cell-free spaces and representing the prospective site of the medial longitudinal (mlf) and lateral longitudinal (llt) tracts. Nerve fibers were also traced in the brain stem of young embryos. Axons were seen to travel in the early mlf and llt, in close proximity to the regions of early-generated neuronal columns. The data suggest that the precocious neurons that are organized in a definite pattern could somehow be involved in the guidance of some longitudinal axonal tracts, either by directly promoting the formation of an adequate terrain in the marginal layer, or by inducing other cells to do so.
Animals↗
Disposition of homocysteine in rat hepatocytes and in nontransformed and malignant mouse embryo fibroblasts following exposure to inhibitors of S-adenosylhomocysteine catabolism.
S-Adenosylhomocysteine (AdoHcy) is catabolized to adenosine and homocysteine through the action of AdoHcy hydrolase, and this reaction is the only known source of L-homocysteine in vertebrates. The disposition of endogenously formed L-homocysteine was investigated in isolated rat hepatocytes and nontransformed and malignant C3H/10T1/2 mouse embryo fibroblasts exposed to 3-deazaaristeromycin or D-eritadenine, compounds which are potent inhibitors of AdoHcy hydrolase. Cells in suspension release large amounts of L-homocysteine into the extracellular medium whereas small amounts are retained within the intracellular compartment. The L-homocysteine egress is inhibited by 3-deazaaristeromycin or D-eritadenine in a manner which closely parallels the inhibitory effect on AdoHcy catabolism, suggesting that L-homocysteine egress may be coupled to its formation from AdoHcy. In liver cells, the accumulation of AdoHcy exceeded the inhibition of L-homocysteine egress, whereas in the fibroblasts inhibition of egress equalled the accumulation of AdoHcy. Inhibition of AdoHcy catabolism was associated with an increase in both free and protein bound L-homocysteine in liver cells, whereas depletion of intracellular L-homocysteine occurred in the mouse embryo fibroblasts under these conditions. These data suggest that some properties of nucleoside analogues may be related to their effects on L-homocysteine metabolism. Furthermore, L-homocysteine is exported into the extracellular medium in proportion to the formation from AdoHcy, and extracellular L-homocysteine may be a measure of the balance between L-homocysteine formation and utilization.
Adenine↗
Events governing organization of postmigratory neurons: studies on brain development in normal and reeler mice.
The purpose of the present work is to examine some of the mechanisms responsible for the early architectonic differentiation of the central nervous system, as well as for the abnormal development which occurs in certain hereditary malformations. In order to approach these questions, the embryonic development of the cerebral cortex, the cerebellum, the inferior olivary complex and the facial nerve nucleus has been studied in normal and reeler mutant mice, using morphological methods. The adult reeler phenotype is characterized not only by extreme laminar abnormalities of cell positioning in the telencephalic and cerebellar cortices, but also by relatively less extreme, though distinct abnormal architectonics in non-cortical structures such as the inferior olive and the facial nerve nucleus. Study of the embryonic development of these structures reveals that neurons are generated at the normal time and migrate along normal pathways. Moreover, the processes of directional axonal growth, differentiation of class specific features of neurons and glia, and synaptogenesis appear similar in both genotypes and are probably not directly affected by the reeler mutation. However, in all instances, the early architectonic organization achieved by reeler cortical, Purkinje, olivary or facial neurons at the end of their migration is consistently less regular than in normal embryos. In addition, these anomalies become amplified during the later developmental period. This evidence for the early appearance of abnormalities in reeler embryos indicates that the disposition of neurons at maturity cannot be exclusively regarded as secondary to the maturation of cells, neurites and connections, but is contingent upon a specific mechanism. One may infer that the presence of a normal allele at the reeler locus is necessary for the normal completion of this histogenetic step, which consequently is submitted to genetic control. Although the factor(s) responsible for the stable configuration of the early architectonics is unknown, various hypotheses are considered. Several lines of evidence are presented which argue against a major role being played by diffusible factors, mesodermal components and afferent fiber systems. Two mechanisms are considered particularly worth evaluating: (1) a diminution of relative adhesivity between neurons and radial glial fibers at the end of migration, and (2) a stabilization of neuronal configuration by selective recognition-adhesion among postmigratory neurons. The reeler gene could, directly or indirectly, affect these cell-cell interactions.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
Embryonal disposition of salicylate: in vivo-in vitro comparisons.
The distribution of salicylate to embryonal compartments for in situ and in vitro rat embryos under equivalent exposure conditions, and salicylate disposition in the in vivo mid-gestation embryo and late gestation fetus, were compared. Pregnant Sprague-Dawley CD rats were exposed to steady-state blood levels of salicylate by infusing 14C-salicylic acid iv for a 24 hour period from gestation day 11.5 to 12.5. Cultured Sprague-Dawley rat embryos (in medium consisting of 100% male rat serum) were exposed to the steady-state 14C-salicylate concentration achieved in maternal serum in vivo for the same 24 hour developmental period. At the end of the exposure period radioactivity in visceral yolk sac, extra-embryonic fluid and embryos, and in maternal tissues, was measured. The distribution of salicylate to embryonal tissues was statistically comparable in vivo and in vitro, although the embryos in vitro accumulated slightly (but not significantly) less of the chemical. There was considerable binding of salicylate by maternal serum and culture medium proteins: less than 20% of the chemical was free at the 40 micrograms/ml concentration used in this experiment. Consequently, the salicylate concentration in embryonal compartments appeared to be quite low when compared to the surrounding serum/medium, but was actually equal to or greater than the concentration of unbound salicylate in serum or culture medium. The proportion of free salicylate in serum increased at concentrations higher than 40 micrograms/ml, resulting in somewhat higher concentrations of salicylate in in vitro embryos and extraembryonic fluid (as compared to medium) when cultured in the presence of 200 or 400 micrograms/ml salicylate.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗