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1.
Iran is the only Muslim country that has legislation on embryo donation, adopted in 2003. With an estimated 10–15% of couples in the country that are infertile, there are not any legal or religious barriers that prohibit an infertile couple from taking advantage of Assisted Reproductive Technologies (ARTs). Although all forms of ARTs available in Iran have been legitimized by religious authorities, there is a lack of legislation in all ARTs except embryo donation. By highlighting ethical issues in embryo donation, the paper presents a critical review of the Act of Embryo Donation in Iran. The paper argues that the Act does not provide enough safeguards for the future child and assurance for the safety of the donated embryos. It also does not restrict embryo donation to surplus embryos from infertile couples and is silent about the number of embryos that could be donated by each couple as well as the number of recipients for donated embryos by a couple. The Act is also silent about the issues of genetic linkage (nasab) and heritage which are challenging issues, especially in a conservative Islamic society. As a result, the future child may not inherit from their birth parents, as it is not required by the Act, or from the genetically related parents under the anonymity policy. Finally there is no standard national protocol or guidelines to evaluate the safety of the donated embryos. The paper concludes that despite its benefits, the Act lacks clarity, and it is subject to misunderstanding and confusion.  相似文献   

2.
Deckers J 《Bioethics》2005,19(3):251-271
On 22 January 2001, the UK became the first country to approve of embryonic stem cell research by passing the Human Fertilisation (Research Purposes) Regulations 2001, which legislated new research purposes for which early embryos can be used, in addition to those approved by the Human Fertilisation and Embryology Act 1990. Legal advisory committees, most notably the Chief Medical Officer's Expert Group and the House of Lords' Select Committee, have offered various reasons, which can also be found in the ethics literature, to justify this change. Those examined here are the views that: 1. Early embryos lack relevant qualities (or 'the argument from lack of qualities') and 2. Early embryos only have a potentiality to become humans with moral status (or 'the argument from potentiality'). The validity of these arguments is questioned and a case is made for egalitarian speciesism. Embryos have moral status (used here in the restricted sense of the status possessed by all members of the class of beings which deserve the greatest moral significance in equal measure). They have more value than the value that should be assigned to non-human beings from the start of fertilisation. Current UK legislation on embryo research is immoral.  相似文献   

3.
The development of lizard embryos is typically initiated at fertilization and continues until birth or hatching. In contrast, embryonic development of some chameleons is arrested at the gastrula stage, and embryos remain at this stage for months after the eggs are laid. Our research tested the hypothesis that increased temperature, moisture, or both, are associated with the resumption of development by diapausing embryos of Chamaeleo calyptratus, the veiled chameleon. After 40 days of incubation at 25 degrees C in a relatively dry substrate, eggs were subjected to: 1) no change in temperature or moisture, 2) no change in temperature but change from a dry to a wet substrate, 3) change to a warmer temperature but no change in substrate moisture, or 4) an increase in both temperature and substrate moisture. Overall, embryos initiated development after 50-60 days to 80 or more days of incubation. Neither substrate moisture nor water uptake by eggs was related to the interval when development resumed. In contrast, development was initiated about 10 days earlier for eggs in the high temperature treatment compared to eggs in the low temperature treatment. Our results suggest that neither water availability nor water uptake by eggs affect the length of diapause but that an increase in ambient temperature initiates development of diapausing embryos of C. calyptratus.  相似文献   

4.
Recognition of unacceptable cruelty to animals in pasttimes such as bull-baiting, dates in Britain from the early 19th century. The Society for the Prevention of Cruelty to Animals was founded in 1824. Several bills to curb cruelty were discussed in Parliament, and the Cruel and Improper Treatment of Cattle Act was passed in 1822. Other Acts have followed over the years. Cruelty in the form of painful scientific experiments, including dissection of living, conscious animals, vivisection, was proscribed by the Cruelty to Animals Act 1876. That Act required anyone wishing to experiment with animals to obtain a licence from the Secretary of State. Conditions for issue of licences were strict and remain so to this day. The Act is still valid, and is enforced by the Home Office, with its medical and veterinary Inspectors. The Cruelty to Animals Act 1876 allows experiments on animals under strictly controlled conditions. Experiments must have the clear objective of improving the welfare of man and/or animals. Benefits from experiments carried out under the Act have been enormous, covering every aspect of diagnosis, treatment, and prophylaxis in human and veterinary medicine. Coincidentally, the welfare of laboratory animals has also been greatly improved. There has always been some opposition to the use of animals in biomedical research. The subject is emotive but, by and large, discussion has been rational and within the law. In recent years, however, the morality of using experimental animals has been examined more closely. The possibility of replacing them by alternative methods has been investigated. Where these alternatives are applicable, they are used and further research on them continues. The questioning of animal experiments has emphasized the need to look constantly at animal welfare to ensure humane treatment of all animals, especially those restricted in a laboratory or on a farm. Attention has been drawn in this work to our existing laws protecting animals, but new legislation is being demanded, not only by some lay welfare groups but also by scientists. Hence, it has become very important to discuss various ways of ensuring animal welfare, including by legislation, especially with those knowledgeable in laboratory animal science and animal experiments.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   

5.
Nitric oxide (NO), which is produced from l-arginine by three isoforms of NO synthase (NOS), has been implicated in reproductive functions. However, the specific role of NOS isoforms in gamete function and fertilization is not clear. Three types of NOS knockout mice were super ovulated and fertilized in vitro and in vivo. The sperm count and motility, in vivo and in vitro fertilization rate as indicated by two-cell embryos and blastocyst rate were examined. The sperm count and motility from all three knockout mice were not significantly different from that of the wild type. Inducible NOS (iNOS) knockout mice were found to have the largest number of two-cell embryos/mouse collected after fertilization in vivo (P<0.01), but the rate of blastocyst formation from two-cell embryos in vitro was similar for all three knockouts. The rate of in vitro fertilization using either iNOS-deficient sperm or oocytes, but not those deficient in the other two NOS isoforms, was significantly elevated when compared to that in the wild type (P<0.001). While all three types of NOS do not seem to play a significant role in pre-ejaculated sperm function, iNOS may play an inhibitory role in sperm and oocyte functions affecting the process of fertilization and early embryo development.  相似文献   

6.
Oocytes from most animals arrest twice during the meiotic cell cycle. The universally conserved prophase I arrest is released by a maturation hormone that allows progression to a second arrest point, typically metaphase I or II. This second arrest allows for short-term storage of fertilization-competent eggs and is released by signaling that occurs during fertilization. Nematodes are unique in that the maturation hormone is secreted by sperm rather than by the mother's somatic tissues. We have investigated the nature of the second arrest in matured but unfertilized Caenorhabditis elegans embryos using time-lapse imaging of GFP-tubulin or GFP-histone. Unfertilized embryos completed anaphase I but did not form polar bodies or assemble meiosis II spindles. Nevertheless, unfertilized embryos assembled female pronuclei at the same time as fertilized embryos. Analysis of embryos fertilized by sperm lacking the SPE-11 protein indicated that fertilization promotes meiotic cytokinesis through the SPE-11 protein but assembly of the meiosis II spindle is initiated through an SPE-11-independent pathway.  相似文献   

7.
In vitro fertilization and embryo transfer: a brief overview   总被引:2,自引:0,他引:2  
The in vitro fertilization process breaks down into three essential components: induction of ovulation, fertilization of the oocyte, and development of embryos that are transferred into the uterus. Problems may arise resulting in failure at any one of these junctions. In 1984, the World Congress on In Vitro Fertilization was held, looking at 9,641 laparoscopies yielding 1,101 clinical pregnancies, with an overall pregnancy rate of 11 percent--clearly indicating that in vitro fertilization/embryo transfer (IVF/ET) was an idea whose time had come. Ovulation induction is monitored by both the use of ultrasound and daily estradiol levels, ultrasound indicating the number of oocytes that will be available for capture, and estradiol indicating in an indirect way the quality of those oocytes. It is a major aim in each patient to obtain at least four embryos, since this optimizes success rates. Ovulation induction at Yale is carried out with a high-dose human menopausal gonadotropin (HMG)/human chorionic gonadotropin (HCG) regimen. This regimen has insured us a success rate of 17 percent clinical pregnancies per laparoscopy. In the future, modification will occur in the process with cryopreservation of oocytes and embryos, and gamete manipulation. The modifications will be effected primarily to increase pregnancy rates. Research will continue mainly to delineate better biochemical markers for oocyte quality, but also to further explain the mystery of implantation.  相似文献   

8.
In vitro techniques for production of bovine embryos including in vitro oocyte maturation (IVM), fertilization (IVF) and culture (IVC) are becoming increasingly employed for a variety of research purposes. However, decreased viability following cryopreservation by conventional methods has limited commercial applications of these technologies. A practical alternative to facilitate transport would be to arrest development by chilling without freezing. The present research was undertaken to evaluate chilling sensitivity of IVM-IVF embryos at different stages of development, and to determine possible beneficial effects of cysteamine treatment during IVM, previously shown to enhance embryo development in culture, on survival following chilling at different stages. Embryos produced by standard IVM-IVF-IVC methods were chilled to 0 degrees C for 30 min at 2-cell (30-34 h post-insemination, hpi), 8-cell (48-52 hpi) or blastocyst (166-170 hpi) stages. Viability after chilling was assessed by IVC with development to expanded blastocyst stage determined on days 7 and 8 post-insemination (pi) and hatching blastocyst stage determined on days 9 and 10 pi. Control embryos at the same stages were handled similarly, but without chilling, and development during culture similarly assessed. The effect of cysteamine supplementation (100 microM) of the IVM medium was determined for both chilled and non-chilled (control) embryos. Cysteamine supplementation during IVM had no significant effect on oocyte maturation or fertilization, but increased the proportions of oocytes developing to blastocyst stage by day 7 (13.7+/-0.9% versus 7.2+/-0.9%; P<0.05), total blastocysts (20.5+/-0.9% versus 15.3+/-1.3%; P<0.05), and hatching blastocysts (16.8+/-1.6% versus 12.0+/-1.5%; P<0.05). The greater survival in terms of hatching (78.6+/-7.0) following chilling of blastocysts produced by IVM-IVF of oocytes matured in media supplemented with cysteamine offers promise for applications requiring short-term storage to facilitate transport of in vitro produced bovine embryos.  相似文献   

9.
H Ishikawa  K Omoe  A Endo 《Teratology》1992,45(6):655-659
We previously showed that digit formation in mouse embryos from early morning mating seemed to progress faster than those from overnight mating. In this study, to confirm this phenomenon, we examine whether the embryos from normal (0 hr from ovulation to fertilization) and delayed matings (3, 6, or 9 hr from ovulation to fertilization) respond differently to some acute teratogens when they are treated at the same time point from mating. Five mg/kg of cytosine arabinoside (Ara-C) was given to pregnant mice intraperitoneally at 246, 249, or 252 hr (day of gestation (dg) 10) after mating. The patterns of Ara-C induced digit malformations in embryos from the delayed mating groups were those of more advanced stages, when compared with normal mating groups with the same time intervals from mating to Ara-C treatment. In other words, oocytes fertilized up to 9 hr after the presumed time of ovulation could grow similarly to those of normally fertilized oocytes. This catch-up phenomenon suggests that the ovulation clock should be used for the startpoint of the time scale of the growth and differentiation of embryos rather than fertilization clock.  相似文献   

10.
Under Chinese law, the juridical status of the embryo and the foetus is unclear, mainly because the existing legislation can be subject to diverse interpretations due to its ambiguous language. Lack of clarity with the law has led to different understandings amongst Chinese legal scholars. However, although there has been no consensus, there has been a clear tendency to deprive embryos and foetuses of legal status or personhood, thereby excluding them from entitlement to fundamental rights, an understanding reinforced by the Confucian view of the beginning of life. It is expected that in the near future the Chinese courts will face issues involving embryos and foetuses more often, such as disputes over in vitro embryos. The lack of legal precedent could result in contradictory resolutions, therefore, the law should clarify the legal status of embryos and foetuses and accord to prenatal life special respect and treatment.  相似文献   

11.
Infertility in many valuable cows could be overcome by transferring ovarian oocytes to host animals for fertilization. Oocytes were recovered from 134 cows stimulated with gonadotropin. Ovulations occurred as early as 12 hr after first observance of estrus and by 24 hr ovulations were present in 73% of the donors. With 2000 IU PMSG donors averaged 19.4 visible follicles from which oocytes were recovered 60% of the time. Large doses of gonadotropin produced more visible follicles (mean of 52.9) but a low recovery rate of oocytes (32%) and a lower incidence of maturation within the oocytes (20%). Fertilization depended on the condition of the oocytes and the ease of transfer to the oviducts of hosts. Using this technique to obtain large numbers of embryos necessitates treatments either to render immature oocytes fertile or to obtain large numbers of mature follicular oocytes.  相似文献   

12.
Human embryonic stem cells (hESC) are undifferentiated cells derived from an early embryo that can grow in vitro indefinitely, while retaining their capability to differentiate into specialized somatic cell types. Over the last decade there has been great interest in derivation and culture of these cells, as they can potentially provide a supply of readily available differentiated cells and tissues of all types to be used for therapeutic purposes in cell transplantation in humans, as well as for other medical uses such as drug discovery. The source of hESC lines is usually excess human embryos from in vitro fertilization treatments, although novel ways of producing hESCs have been suggested recently. The actual methods of hESC derivation have not changed greatly since the first report by Thomson et al. in 1998 . However, the main emphasis over the last several years has been in finding defined conditions for derivation and culture of hESCs, because to enable the clinical use of hESC for cell transplantation, the use of animal derived biological components is no longer acceptable. For basic research, the aim is to replace even human derived materials with completely defined systems. In this paper we describe methods utilized in our laboratory for hESC derivation and describe two studies conducted in an attempt to improve derivation efficiency and to enable research outcomes to be achieved using fewer embryos.  相似文献   

13.
Data on Aging     
Federal payment for hospitalization and partial medical care of certain citizens 65 and over is proposed in H.R. 4222. There are several important aspects of this proposed legislation which merit consideration, notably (1) How great is the actual need? and (2) Who would actually be covered by the proposed measure?1. The need for subsidized hospitalization and medical care is believed to be distinctly limited. A national study of the total life situation of those 65 and over (by Wiggins and Schoeck) showed that 90 per cent of the respondents reported no unmet medical needs of which they were aware. About 96 per cent reported no medical debts. This would leave presumably 4 per cent with such debts.2. The proposed legislation would cover those eligible for benefits under the Social Security Act and the Railroad Retirement Act, but not other elderly persons.The Wiggins-Schoeck Report has been bitterly assailed by supporters of H.R. 4222 as being nonrepresentative and incomplete. Its authors (in a recent letter to Science) point out that it is indeed representative of the older population currently designated in H.R. 4222, and that it intentionally omitted those segments which would not be covered by H.R. 4222. In other words the data on needs of elderly persons as uncovered by Wiggins and Schoeck is pertinent to the legislation at hand. For this reason it is believed that physicians will be interested in reading the reply of these authors to the criticisms of their survey.With the permission of Science and of the authors, it is reprinted herewith.  相似文献   

14.
The activity of a cytoplasmic factor (MPF), capable of inducing nuclear membrane breakdown (germinal vesicle breakdown) when injected into amphibian oocytes, has been studied during the course of early cleavage in amphibian embryos. Mature egg cytoplasm was found to contain high levels of this activity, but this was quickly lost after fertilization or artificial activation. MPF activity later reappeared in the egg cytoplasm and started to cycle with time. The peak of embryonic MPF activity during each cycle coincided with the time the embryonic nuclei were entering the G2-M transition, i.e., mitosis. However, in colchicine-arrested embryos, this activity remained at an elevated level and no longer oscillated. The timing of the appearance and disappearance of this activity appeared to be under the control of the cytoplasm because such behavior was still observed in enucleated eggs. Continued protein synthesis in the embryo was required for the reappearance, but not for the disappearance, of this activity. MPF, previously thought to be restricted to oocyte maturation, may play a more general role in controlling nuclear membrane breakdown during mitosis as well as meiosis.  相似文献   

15.
The present study investigated the effect of increased water temperature on sperm motility when activated in water, on egg water hardening, on the fertilization process and on embryonic development in brown trout, Salmo trutta. Brown trout gametes had a broad temperature optimum ranging from 3 to 15°C. In this temperature range the processes of egg water hardening and fertilization were unaffected. Motility duration was also not affected. The percentages of initial sperm motility and swimming velocity were lower at 9–15°C than at 3–7°C, while the percentage of locally motile spermatozoa was higher. Exposure of brown trout embryos to ≥11°C resulted in reduced percentages of hatched larvae and in increased percentages of malformed larvae. More advanced ontogenetic stages (stages ≥9 according to Ballard [1973]) showed higher tolerance to increased temperature than did less advanced stages (stages <9) when the percentage of eyed stage embryos was used as the evaluation end point. However, when the percentages of hatched larvae and normal shaped larvae were used as evaluation end points, no differences in thermotolerance could be found between the different otogenetic stages.  相似文献   

16.
研究喜马拉雅旱獭(Marmota himalayana)繁殖生物学特征,对阐明其种群数量变动,进行数量监测以及探索动物流行病学有着实践和理论意义。国内赵中石(1982)对天山旱獭(Marmota baibacina)有过研究,而喜马拉雅旱獭尚无报道。作者于1982-1984年对青海湖东北岸热水滩地区(下称研究区,该区于1960-1979年进行了持续地灭獭工作)进行了连续3年的调查,并与未经人群干扰的乌兰脑滩地区(下称对照区)作对比,研究了喜马拉雅旱獭繁殖生物学特征。  相似文献   

17.
LIF is twice transiently expressed in the mouse uterus, first at the time of ovulation and again just prior to implantation, and studies have demonstrated a beneficial influence of this cytokine on embryo development in several species. We have investigated the effect of LIF on gametes in vitro, on the hypothesis that the ovulatory peak of LIF can exert an influence on gametes present within the oviduct. We also investigated the effect of LIF on in vitro fertilization and embryo development, in oocytes from adult sheep and from prepubertal lambs that lack the preovulatory hormone surge and that are unable to sustain early embryonic development. A higher rate of pronuclear-stage embryos derived from both, adult and prepubertal female, was obtained when in vitro fertilization was performed in the presence of LIF, and there was an improved cleavage of parthenogenetic embryos when incubated with LIF immediately following activation. In contrast, LIF was found to have no influence on the viability of ram semen. In vitro fertilized two-cell stage embryos from adult sheep and prepubertal lambs, cultured in defined medium enriched with LIF, both reached the blastocyst stage at similar rates to control embryos. However, LIF exerted a positive influence on the quality of the blastocysts as revealed by significantly higher number of ICM cells and total number of cells. Together, these data demonstrate that LIF exerts a beneficial effect on sheep oocytes and embryos in vitro, but only at stages concomitant with steroid hormones surges.  相似文献   

18.
Goldfish Carassius auratus embryos were subjected to artificial ultraviolet‐B (UVB) radiation (280–320 nm) at various times during development to evaluate the effects on production of anatomically normal larvae. The UVB radiation used in these experiments included a higher proportion of shorter wavelengths compared to the natural spectrum. The development of embryos exposed to UVB for 2 or 4 h at 26 h post‐fertilization was severely impaired whereas similar exposures at 50 or 74 h post‐fertilization had no effect. A 2 h exposure to UVB commencing at 2 h post‐fertilization did not adversely affect embryonic development whereas a 4 h exposure to a lower dose did. At 50 h post‐fertilization, when embryos were normally resistant to UVB, denial of access to visible light and UVA before, during and after exposure to UVB caused impairment of development. Analysis of DNA fragment length after incubation with an endonuclease suggested that UVB damage at 50 h was caused by formation of pyrimidine dimers. This study demonstrated that the sensitivity of goldfish embryos to UVB varied during development and that resistance to UVB in later developmental stages included a photorepair mechanism.  相似文献   

19.
Tritrichomonas foetus, a world-wide distributed parasitic protozoan is a cause of infertility and abortion. There is no documented information on the susceptibility of bovine embryos to the parasite. To determine the effect of T. foetus on fertilization and embryonic development of preimplantation bovine embryos, we added approximately 10(4)/ml or 10(6)/ml T. foetus (Belfast strain) to sperm cells and oocytes prior to in vitro fertilization (IVF) or to presumptive zygotes 24 h post-fertilization. Light and scanning electron microscopy (SEM) revealed that exposure of oocytes or embryos at any stage of development to T. foetus caused rapid adhesion of the trichomonads to the embryonic intact zona pellucida (ZP) and to trophoblastic cells of hatched blastocysts. Treatment of contaminated embryos with 0.25% trypsin for 3 min did not render them free from T. foetus. Motile parasites were not observed after 18 h incubation in IVF medium, or after 72 h in synthetic oviductal fluid (SOF) embryo culture medium. The percentages of cleaved zygotes, blastocysts and hatched embryos resulting from culture of experimental and uninfected control groups of embryos were not different (P > 0.05). Tritrichomonas foetus was not detected in embryonic cells of ZP-intact or hatched embryos when examined by transmission electron microscopy (TEM). In conclusion, T. foetus has no detrimental effect on the fertilization and development of IVF embryos and the potential risk of transmission of trichomonosis is unlikely, due to the limited survival of the parasite in IVF culture conditions.  相似文献   

20.
M.P. Boland 《Theriogenology》1984,21(1):126-137
The oviducts of both oestrous and pseudopregnant rabbits can be used for the successful culture of mammalian embryos for short periods. This has alowed some selection to be made on the embryos as they are examined on at least two occasions before final transfer. Not only have pregnancy rates been normal, but in some instances they have been higher following a limited period (2–3 days) in the rabbit oviduct. It would appear that these higher pregnancy rates result from a more intensive selection of embryos at the time of transfer rather than from some substance acquired during storage in the oviduct. However, the system is not without disadvantages. There is some loss of embryos (15–30%) in the oviduct and all embryos recovered may not have developed at the normal rate.The rabbit oviduct has been used as a site of xenogenous fertilization. Initial reports indicate that success in that area is lower than when using large animals as the site of fertilization. With more widespread interest in the use of microsurgery in embryos, the rabbit oviduct has been used for the short term storage of agar cylinders and has been found to be unsuitable because of the high rate of degeneration of agar chips. However, the rabbit oviduct is still useful as an experimental tool in the manipulation of embryos from the domestic species.  相似文献   

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