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A M Junca

Publications and source records attributed to A M Junca.

At least 37 records · Page 2Linked to original sources
PubMed1988

[Timing of embryo transfer and success of pregnancy in the human].

The best moment for human embryo transfer has not yet been accurately determined. The human uterus is able to receive young embryos (2, 4 cell-stage and even pronucleated eggs), insure their growth and implantation at a rate that does not exceed, however, 15% for one transferred egg. At the present time in vitro culture to the blastocyst stage, which impairs human embryo viability, should be avoided. Contrary to classical IVF, it becomes possible to dissociate embryo and endometrial ages when transferring frozen-thawed eggs. Our study concerns 443 spontaneous, stimulated or artificial cycles, performed in patients with normal or without endogenous ovarian function (tabl. 1). There was trend towards enhanced pregnancy rates (17%) for synchronous as compared to one-day asynchronous transfers (9%) (tabl. 2). Similar data, widely stated in mammals, emphasize the necessity of a precise chronology of embryo transfer. Embryos only survive and get implanted when placed in a receptive uterus. The onset of the refractory period appears to be closely linked to the maternal steroid environment. Consequently, no pregnancies arose from transfer of donated embryos beyond 6 days of progestative supply in women deprived of endogenous ovarian function. In the same way, administration of progesterone 40 h before oocyte recovery seemed to advance the refractory phase. Indeed, a reduction in the pregnancy rate per transfer was observed in such circumstances without any obvious impairment of embryo viability (tabl. 4). The best pregnancy rate was obtained in synchronous transfers while a one-day disynchronization reduced this rate by half.

Animals↗
PubMed1988

[Failure of embryonic development].

Abnormal embryo development represents the major cause of implantation failures and accounts for the low rate of human fertility in vivo or in vitro. Chromosome abnormalities are widely involved in this process as 26% of oocytes, 8% of fertilizing spermatozoa and 29% of preimplantation embryos carry a chromosome aberration induced by meiotic (aneuploidy) or mitotic (mosaic) non disjunctions. Fertilization anomalies (possibly increased by in vitro procedures) were recorded: 1.6% of embryos resulted from parthenogenesis and 6.4% were polyploid (mainly polyspermic). A morphological, histological and ultrastructural study of embryos recovered after in vivo or in vitro fertilization showed some anomalies: multinucleated blastomeres, cytoplasmic fragments in the perivitelline space, vacuoles, associated or not with developmental impairement. Finally, a few embryos appeared to be free of abnormalities. The analysis of in vitro developmental capacities of normal or abnormal embryos showed great differences: parthenones exceptionally reached the blastocyst stage and therefore probably did not implant. The diploid embryos used in this study were (for ethical reasons) more or less fragmented and gave evidence of low developmental capacities, limited to the 3rd cleavage. Triploid embryos were able to further develop as some of them reached the early blastocyst stage; they represented the major cause of chromosomal 1st trimester abortions. It is interesting to note that 47% of tripronucleated ova divided directly into 3 and 6 cells (probably via a tripolar spindle) instead of 2 and 4 cells as classically described. Finally, tetraploid embryos expressed a precocious lethality as none developed beyond the 3rd cleavage. To conclude, many embryos carry genetic and/or cytological abnormalities which may be enhanced by superovulation treatments. The selection proceeds through all pre- and postimplantation steps, and as a matter of fact nor more than 0.6% newborns are abnormal.

Chromosome Aberrations↗
PubMed1988

[Chromosome analysis of ovocytes and human embryos collected after fertilization in vitro. A model of natural selection against aneuploidy].

Fertilization in-vitro offers the possibility of studying the karyotype of ovocytes obtained after superovulation, when they are not fertilized. Among 120 ovocytes, 30 p. cent presented a chromosomal anomaly. The same study was carried out on morphologically normal or abnormal embryos - and the percentage of chromosomal anomalies approximates here 27 p. cent. These studies offer a model of natural selection against chromosomal anomalies and confirm the limiting role of these anomalies in the success of FIV.

Aneuploidy↗
PubMed1987

Chromosome investigations in early life. II. Human preimplantation embryos.

Cytogenetic analysis of 68 human embryos at the 2- to 8-cell stage was performed according to Tarkowski's technique. Sixteen per cent of diploid embryos showed abnormalities, essentially diploid/haploid or triploid/haploid mosaicism. Considering the aspect of the embryos, 11% of healthy looking and 19% of fragmented embryos were chromosomally abnormal without, however, any statistical significance in this small series. Only 46.7% of the tripronucleate fertilized eggs showed a triploid chromosome complement. In 20% of the cases, however, diploid metaphases were found, and in the last 30% a triploid/diploid mosaicism. One per cent of the oocytes displayed a single pronucleus, and the resulting embryos contained haploid sets of chromosomes suggesting a parthogenetic activation. The overall rate of chromosome abnormalities, including 16% of abnormal diploid eggs, 6% of polyploid and 1% of haploid embryos, thus reaches 23% in this series.

Aneuploidy↗
PubMed1987

Human embryo cryopreservation, extrinsic and intrinsic parameters of success.

Freezing and thawing (F - T) was applied to 490 early human embryos using propanediol as cryoprotectant. The survival rate of embryos frozen with propanediol alone did not exceed 31% (26/83). The combination of propanediol and sucrose, however, significantly increased the percentage of surviving (248/407 = 61%) and intact (188/407 = 46%) embryos and seemed to enhance embryo viability as suggested by the implantation rate (14.5 versus 8%) without, however, any statistical significance. Embryo survival, but not viability, was correlated with morphological features, whereas neither the age of embryos (1, 2 or 3 days post-insemination) nor the segmentation stage (regular or intermediate) were involved in F - T ability. Thirty-eight F - T embryos implanted when replaced in utero, representing 8% of all F - T embryos and 14% of the F - T replaced embryos. The pregnancy rate per transfer reached 19% (35/185) and was identical to the pregnancy rate per transfer of fresh embryos (253/1149 = 22%). In oocyte donation, too, embryo freezing did not impair the pregnancy rate (25%). In spontaneous cycles, synchronous transfer gave better results than asynchronous transfers (20 versus 10%), but spontaneous cycles had no significant advantage (16% pregnancy/transfer) as compared to stimulated (26%) and artificial (27%) cycles.

Blastomeres↗
PubMed1987

From oocyte to embryo: a model, deduced from in vitro fertilization, for natural selection against chromosome abnormalities.

A cytogenetical analysis was performed on 151 unfertilized oocytes, 22 fertilized eggs at the pronuclear stage, and 108 cleaved embryos obtained in the course of in vitro fertilization (IVF). Thirty-two per cent of unfertilized oocytes were abnormal, carrying nullisomies or disomies, mainly of D and G chromosomes, and a structural anomaly (Gq-) in one case. Fertilized eggs showed frequent asynchronism in the development of pronuclei and only 2 out of 8 karyotyped pronuclei were normal. Cleaved embryos were classified according to the number of pronuclei observed 17 hours after insemination. One per cent displayed a single pronucleus, and haploid chromosome complements were found in the corresponding cleaved embryos which were considered to be parthenotes. The rate of chromosome abnormalities of diploid eggs depended on their morphological aspect. Healthy cleaved embryos carried 12.5% of anomalies while this rate reached 37% in fragmented embryos (p less than 0.05). Lastly, 6% of fertilized eggs displayed three pronuclei or more. Only 41% of the corresponding embryos were triploid. Diploidy or diploidtriploid mosaicism were often encountered. This leads to a 21% rate of abnormalities in the preimplantation embryos. Parental karyotyping and HLA typing were carried out in a series of eight couples with in vitro idiopathic infertility or recurrent embryo degeneration in vitro. No abnormality was noted. According to these results, a model of natural selection of normal conceptuses is proposed.

Aneuploidy↗
PubMed1986

Transvaginal sonographically controlled ovarian puncture for oocyte retrieval for in vitro fertilization.

Two hundred twenty-two patients took part in a trial of follicle puncture via the transvaginal route under sonographic control for the purpose of in vitro fertilization (IVF). Induction protocols were mainly human menopausal gonadotropin (hMG) + human chorionic gonadotropin (hCG) and clomiphene + hMC + hCG. In 79.7% oocyte aspiration could be achieved without difficulty via the transvaginal route. An average number of 4.7 oocytes per attempt was obtained; 10.7% evolutive pregnancies were obtained. No major incident was noted. This technique offers several crucial advantages: it reduces surgical risk, reduces the length of the patient's stay in hospital as well as the overall cost of the procedure, and it also makes possible puncture in some cases hitherto regarded as excluded.

Female↗
PubMed1986

Timing of in-vitro fertilization of cumulus-free and cumulus-enclosed human oocytes.

In humans, in contrast to other species, sperm capacitation requires a very short time, as in-vitro fertilization has been obtained after only 45 min of contact between oocytes and spermatozoa capacitated for 1 h. No fertilization occurred, whatever the duration of sperm capacitation, when gamete mixing did not exceed 30 min. On the contrary, 85% of cumulus-free mature oocytes exposed to sperm for 1-4 h were fertilized. The presence of the pre-ovulatory, fully-expanded or compact cumulus mass did not represent a physical barrier to sperm progression, as we observed no delay in fertilization when oocytes were enclosed in the cumulus. The use of a short insemination protocol (1-4 h instead of 17-20 h) did not reduce the fertilization rate of denuded or cumulus-enclosed oocytes and had no significant effect on the morphological appearance of the embryos or their cleavage rates.

Fertilization in Vitro↗
PubMed1986

Chromosome investigations in early life. I. Human oocytes recovered in an IVF programme.

Fifty-five oocytes recovered in an in-vitro fertilization (IVF) programme and remaining unfertilized when observed 42 h after insemination were prepared for chromosomal analysis. Sixteen oocytes displayed no polar body at the time of fixation and were supposed to be in metaphase I. In fact only two of them were in diakinesis, the others containing a diploid set of metaphase II chromosomes indicating that in 89% of the cases oocytes achieved meiosis without any extrusion of the first polar body. Thirty-nine oocytes in metaphase II were analysed. Nine were abnormal showing three D nullosomies, one G disomy, one double disomy for a 3 and a D chromosome, one deletion of the long arm of a G chromosome, one cell with extra chromosomes and/or chromosome breaks, one endoreduplication and one tetraploidy. The overall rate of abnormalities reached 22%. This high rate of chromosome anomalies can be explained by the nature of this population of fertilization failure, the frequently advanced maternal age and the use of superovulation treatments.

Chromosome Aberrations↗
PubMed1985

Sequential use of clomiphene citrate, human menopausal gonadotropin, and human chorionic gonadotropin in human in vitro fertilization. I. Follicular growth and oocyte suitability.

Sequential treatment with clomiphene citrate, human menopausal gonadotropin, and human chorionic gonadotropin was successfully applied to 149 women in the framework of an in vitro fertilization and embryo transfer program and led to the birth of normal children. An average of 3.5 follicles was promoted at each cycle. Oocyte maturity was evaluated at recovery either histologically or with respect to cumulus-oocyte complexes (COC) and correlated to oocyte fertilizability. Three types of COC are described according to cell dissociation and mucification. The most expanded cumulus mass (type I) was highly fertilizable, compared with granular and poorly dissociated cumulus complexes (types II and III, respectively). No improvement in the type II and III oocyte fertilizability was obtained when type I follicular fluid was added to the incubation medium. Moreover, incubation of type III oocytes in medium containing type III follicular fluid seemed to decrease their fertilizability.

Adult↗
PubMed1985

[Characteristics of pregnancies obtained by in vitro fertilization].

193 patients had 212 cycles induced for in vitro fertilisation between May 1983 and May 1984. 20 pregnancies of which 10 are still in progress were obtained with 6 spontaneous abortions. There were 2 so-called biochemical pregnancies and 3 extra-uterine pregnancies. The figure of 17% pregnancies where embryos were replaced totals less than 10% if one considers those pregnancies that really carry on. The number of extra-uterine pregnancies is disturbing. Finally, 2 multiple pregnancies continued, one of them being a quadruple pregnancy. The authors have made a special study to see the parameters of the conditions under which the pregnancies were obtained and the prognosis for such pregnancies.

Abortion, Spontaneous↗
PubMed1984

Acrosome reaction of human sperm used for in vitro fertilization.

The acrosomal reaction of human spermatozoa was assessed, according to a triple-stain technique, at the end of a 17-hour capacitation period in the search for a predictive test of sperm efficiency in an in vitro fertilization program. A 400% increase in the acrosomal reaction rate of the living spermatozoa was observed (4.2% +/- 3.2% before incubation versus 16% +/- 11% after incubation). No correlation could be evidenced between the abilities for spermatozoa to react and to fertilize mature human oocytes in vitro, whatever the initial semen quality. The acrosome reaction rate was not enhanced by the presence of the cumulus oocyte complex, by the selection of motile spermatozoa, or by the increase in albumin concentration of the culture medium.

Acrosome↗
PubMed1982

[Evaluation of the fertility of human sperm by interspecies (man-hamster) in vitro fertilization].

An "in vitro" fertilization test employing zona-free hamster eggs was used to analyse human spermatozoal fertilizing ability. Sperms from 28 men (group 1) whose wives were candidates for "in vitro" fertilization and embryo transfer, and from 5 men belonging to infertile couples (group 2), were evaluated for their ability to penetrate and decondense in zona-free hamster ova. All men had spermiograms in the normal range. A total of 529 eggs were inseminated with spermatozoa from group 1 and the fertilization rate was found to range from 8% to 100% with an average of 57.5%. Of the 130 ova tested with sperm from group 2 individuals, only one showed any evidence of penetration. The fertilization rate and the degree of polyspermy failed to show a significant correlation with sperm concentration in the ejaculate or motility. This cross-species system is a useful additional test to the classic spermiogram and may have a potential value as a diagnostic tool in evaluating human spermatozoal fertilizing capacity, avoiding the ethical and logistical problems associated with fertilization of human eggs "in vitro".

Animals↗
PubMedDate not supplied

Evaluation of human sperm fertility by interspecific (human spermatozoa-hamster oocytes) in vitro fertilization.

The fertilizing capacity of 1) Males with unproven fertility to be admitted to an IVF/RE programme; 2) Probably infertile subjects and of 3) Males with idiopathic infertility, has been evaluated using the humster (HUMan-hamSTER) test. Sixty-seven percent of normal sperms from the IVF-Re couples were capable of fertilizing hamster oocytes, with an average fertilization rate of 52%. In one of the suspect male infertility group sperms were able to fertilize hamster oocytes and in the idiopathic infertility group forty-eight percent of sperms fertilize, but the average fertilization rate is clearly lower. It is surprising that 26% of normal sperms have a negative humster test and fertilize the human oocytes at the same rates (86%) as those having a positive humster test. It means that if statistically and over large populations this test undoubtedly gives good results, when the individual cases are taken into consideration this test does not provide final proof of the patient's infertility. Nevertheless the authors stress that the test may provide a new criterion for determining sperm quality and in the future it might become a complementary examination of the spermogram and postcoital test and supply fundamental data on the mechanism of fertilization (capacitation, acrosome reaction, spermatozoa-oocyte fusion and pronuclei formation).

Animals↗
PubMedDate not supplied

[Oocyte maturity and quality: value of intracytoplasmic sperm injection. Fertility of microinjected oocytes after in vitro maturation].

Many studies in IVF practice, have tried to assess the maturity and quality of oocytes prior to insemination and relate it to IVF efficiency and to the pattern of ovarian stimulation. They were based on the indirect evaluation of the aspect of the cumulus-corona-cell complex (CCC) which was rapidly shown to be poorly correlated to the oocyte nuclear and cytoplasmic maturity in stimulated cycles. For sperm microinjection procedures, oocytes need to be peeled off from any follicular cell through hyaluronidase action in order to gain an easy access to the zona pellucida and the ooplasm. If therefore becomes possible to precisely known at recovery the nuclear status of the oocyte cohort as well as the rate of degenerative gametes. Immature oocytes can be further matured in vitro. Moreover, the ICSI procedure (intracytoplasmic sperm injection) allows a direct assessment of the cytoplasmic maturation, whatever the maturity of the ZP and its receptors and of the plasma membrane. On a preliminary evaluation of 70 ICSI cycles performed in our collaborative group from september to november 1994 and leading to a 24 % pregnancy rate per oocyte pick-up we focused on the true maturation of the oocyte cohort, its outcome and correlation with ICSI efficiency and stimulation protocol. On the 760 oocytes, 13.9% were atretic, 9% at the germinal vesicle stage (GV), 3.4% in metaphase 1 and 73.7% in metaphase 2 at recovery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗