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Biomedical subjects

M Plachot

Publications and source records attributed to M Plachot.

At least 73 records · Page 4Linked to original sources
PubMed1990

Oocyte maturation, fertilization and embryonic growth in vitro.

As the oocyte develops into an embryo, cytological and metabolic events follow one another in an accurate and successive sequence. Meiosis resumes in the ovarian follicle, parallel to cytoplasmic and membrane maturation, from the onset of the ovulatory LH discharge. Only a fully mature oocyte will be recognized and penetrated by a fertilizing sperm, to ensure rapid and synchronous male and female pronuclear growth and early embryonic development. In vitro, the resumption meiosis is easily obtained once the oocyte is withdrawn from the inhibitory influence of the follicle. Cytoplasmic and membrane maturation may however be impaired, leading to fertilization failures or anomalies such as triploidy and even impaired embryo viability. Human in vitro fertilization is nowadays routinely carried out with a high success rate, but in vitro embryonic growth to the blastocyst is still unsatisfactory even with oocytes matured in the ovary, and major improvements are needed to reach optimal viability. Many studies have now been published on human oocyte maturation, fertilization and the growth of embryos in vitro. We give only a brief account of them, due to limited space, and have therefore included topics of most relevance to assisted conception as opposed to those more involved with academic research.

Embryo, Mammalian↗
PubMed1990

Treatment of hyperstimulation during in-vitro fertilization.

In 33 patients treated with a combination of an LHRH agonist (LHRH-A) and gonadotrophin in a long protocol, a biological hyperstimulation occurred (E2 greater than 2500 pg/ml on the day of HCG administration and 4722 +/- 1190 pg/ml the day after, with greater than 10 follicles greater than 12 mm on each ovary). The replacement of fresh embryos were deferred and LHRH-A was continued, and an endometrial biopsy was performed on the theoretical day of replacement (2 days after oocyte recovery). With this technique, we obtained a mean number of 17.9 +/- 7 oocytes, a fertilization rate of 49% and a replacement rate of 87% in a deferred cycles. The overall pregnancy rate of frozen-thawed embryos was 27% in the seven spontaneous cycles, 12 induced cycles and 10 artificial cycles. Only one severe hyperstimulation occurred and this case emphasizes that caution remains necessary even with this technique.

Embryo Transfer↗
PubMed1990

Pregnancies following ovum donation in gonadal dysgenesis.

Between February 1987 and February 1989, 13 women with primary ovarian failure due to gonadal dysgenesis were treated with embryo transfer following ovum donation in 22 cycles. Eight pregnancies were obtained (36.7% per transfer); four births of normal children, two spontaneous abortions and two other pregnancies currently ongoing (between 5 and 8 months). An association of percutaneous oestradiol, oestradiol valenate and intravaginal progesterone was used as hormone substitution and embryo transfer was only performed following assessment of the endometrium during a previous cycle. Apart from the day of embryo transfer, which was the same for all patients (the 2nd day after initiation of progesterone) various prognostic factors were analysed. These were the type of gonadal dysgenesis (45 XO, 46 XX or 46 XY), the number of embryos replaced, whether they had been frozen, whether the egg donor was anonymous and finally the influence of the hormone substitution protocol. Only the number of embryos replaced and the substitution protocol seemed to influence the implantation rate. The other parameters, and in particular the type of gonadal dysgenesis, seemed to have no effect on the results. The pregnancy rate per transfer was 30% for 45 XO (10 transfers), 25% for 46 XX (eight transfers) and 75% for 46 XY (four transfers).

Adult↗
PubMed1990

Ovarian stimulation using human menopausal gonadotrophins with or without LHRH analogues in a long protocol for in-vitro fertilization: a prospective randomized comparison.

In order to evaluate the exact role of GnRH agonists, we have undertaken a randomized prospective study comparing two groups of 90 normo-ovulatory patients, aged less than 38 years and with tubal infertility with no male factor. Luteinizing hormone releasing hormone analogue (DTRP6 administered in a long protocol, for at least 15 days) was associated with human menopausal gonadotrophin (HMG) induction in group I. In group II, stimulation was performed using HMG alone (three ampoules per day in general, from days 2 to 7 of the cycle). Apart from the well known results demonstrated in the literature of a reduced incidence of inadequate responses, an absence of premature luteinization and a greater number of oocytes per retrieval (8.8 +/- 4.9 versus 6.8 +/- 3.2, P less than 0.01 in group II), this study confirms the higher pregnancy rate (21.1 versus 12.2% per cycle and 24.7 versus 17.1% per oocyte retrieval, not significant) and underlines the higher plasma progesterone levels and lower E2/P ratio in group I from D - 1 to D + 5, which could explain a better maturation of the oocytes and the endometrium.

Adult↗
PubMed1990

[Ovarian stimulation for in vitro fertilization using LHRH agonists: comparison of plasma and intra-follicular hormone profiles using "short" and "long" protocols].

Plasmatic estradiol (E2), progesterone (P) and LH were measured during the follicular phase of 343 cycles induced for in vitro fertilization (IVF) using a LHRH agonist in a "long protocol" (Group I) and 76 cycles in a "short protocol" (Group II). Moreover measurements in the plasma and follicular fluid (FF) of E2, P, LH, Delta-4-androstenedione (A), Testosterone (T) and prolactin (PRL) were performed on the day of oocyte retrieval (DO) in 46 women of the group I (111 FF) and 27 of the group II (67 FF). In the group I, plasma LH always remains below 3 mUl/ml, whatever the type of agonist (Buserelin or DTRP6-LHRH) and the type of stimulation (HMG or FSH) are used. On the other hand in the group II, mean plasma LH and P levels from D-5 to D-2 and those of FF LH, T and A on DO are significantly higher than in the group I. These changes are associated with a significant decrease of retrieved oocytes (5.8 versus 7.8 p less than 0.0001), pregnancy rate (15% versus 30%, p less than 0.01) and ongoing pregnancy rate (10% versus 22%, per oocyte retrieval, p less than 0.01). They suggest that the pituitary desensitization could be unsatisfactory with the short protocol use of agonist.

Adult↗
PubMed1990

[Chromosome abnormalities of the fertilized human egg].

In vitro fertilization enabled the study of lethal (parthenogenesis) or sublethal (triploidy, monosomy and trisomy) chromosomal abnormalities in man. According to the literature, 23 to 71% of preimplantation embryos carry a chromosomal defect. Various factors, such as delayed fertilization, early embryo fragmentation or elevated maternal age (greater than 35 years) are related to an increase in the incidence of chromosomal aberrations. These data reinforce the debate on a preimplantation genetic diagnosis in order to select for transfer only viable and apparently normal embryos.

Blastocyst↗
PubMed1990

[Outcome beyond the 1st trimester of 305 pregnancies conceived by fertilization in vitro].

The obstetrical outcome of 305 pregnancies obtained by in vitro fertilization were reviewed: out of 275 pregnancies following fresh embryo transfers, 205 (74.5%) were single, 64 (23.3%) double and 6 (2.2%) triple). We observed increased frequencies of high blood pressure linked to older maternal age, bleeding in the late pregnancy and breech presentation, which could be associated to abnormal insertion of umbilical cord and/or placenta. Multiple pregnancies, especially the triple ones, are of the highest risk (intra-uterine growth retardation, low birth weight). Nevertheless the total fetal mortality remains low in our experience. Data about 22 pregnancies following cryopreserved embryo transfer, 5 after oocyte donation and 3 therapeutic abortions are also given.

Adult↗
PubMed1989

[Treatment of ovarian polycystic syndrome in vitro. Physiopathogenetic considerations].

More than 60% of patients with polycystic ovary disease (PCO) cannot conceive after repeated ovulation inductions with Clomifene citrate although there is ovulation or more frequently follicle luteinization. Because of hyperstimulation, therapy with hMG has been superseded by low doses of purified FSH with variable results according to authors. It has been even claimed that there was no benefit to replace hMG with FSH. However, on the basis of the PCO physico-pathology, namely LH hypersecretion and androgen hyperproduction, it would be rational to associate the desensitization of the pituitary with LH-RH agonist and the ovary stimulation with variable doses of hMG or purified FSH. In the series where such therapy associating LH-RH agonists with purified FSH was applied, the results concerning suppression of LH and androgen secretion, and the occurrence of pregnancy were interesting. However, the risk of hyperstimulation still occurred. Thus, the first part concerns the critical review of these results while, in the second part, our experience in in vitro fecundation will be reported.

Androgens↗
PubMed1989

Cytogenetic analysis and developmental capacity of normal and abnormal embryos after IVF.

Chromosome abnormalities represent the major cause of pre- and post-implantation embryo wastage. Indeed, 29% of embryos produced by in-vitro fertilization have an abnormal karyotype. Parthenogenesis (1.6% of the cases) and triploidy (6.4%) are the only abnormalities detectable 17 h after insemination. A total of 23% of activated oocytes with a single pronucleus (1 PN) and 18% of fertilized eggs with three pronuclei (three PN) remained uncleaved, compared with 4% for diploid eggs. The rate of cleavage for parthenogenes is not different from normal eggs. On the contrary, we observed that 29% of three PN-eggs reached the 5- to 8-cell stage 42 h after insemination when compared to 15% for diploids mainly due to a direct division of 56% of three PN-eggs in three cells. A model of development for triploid eggs is proposed, taking into account physiological and cytogenetic observations. The quality of embryos expressed in terms of morphology did not show any difference between embryos proceeding from parthenogenes or diploid eggs. On the contrary, the rate of fragmentation is decreased for triploid (3%) compared with diploid (13%) or activated (17%) embryos. Embryos resulting from one, two, three or four pronucleate ova display different developmental capacities during 5 days' culture in vitro.

Chromosome Aberrations↗
PubMed1989

Chromosome analysis of spontaneous abortions after IVF. A European survey.

A European survey was carried out in order to evaluate the incidence of chromosome anomalies in spontaneous abortions after IVF. Of the 34 abortuses analysed, 21 had a chromosome anomaly (62%), namely three with monosomy X,14 autosomal trisomies, one double trisomy, one triploidy, one tetraploidy and one translocation. These data show that IVF does not increase the incidence of chromosomal abortuses when compared with natural conceptions (60%).

Abortion, Spontaneous↗
PubMed1988

Programmed ovulation induction and oocyte retrieval for in vitro fertilization.

Forty-two patients underwent programmed ovulation induction for oocyte retrieval. They were treated in the preceding cycles with a progestagen, ethynodiol diacetate, at a dose of 2 mg twice daily. Two groups were defined based upon the stimulation protocol: Group A1 was stimulated with clomiphene citrate and human menopausal gonadotropin (hMG), and Group A2 with follicle-stimulating hormone (FSH) and hMG. They were compared to two randomized control groups of patients who received the same induction but were classically monitored. There was a high proportion of spontaneous ovulations in the programmed group (8/42) compared to the nonprogrammed group (0/42). There was a nonsignificant difference in the number of oocytes obtained or embryos replaced per cycle. Four pregnancies were obtained in the programmed group (24% per transfer), against 10 in the nonprogrammed patients (32% per transfer). The results of this method seem to be better using FSH for ovulation stimulation and a verification of the serum estradiol on the day of induction with human chorionic gonadotropin (hCG) and the following day (semiprogrammed method).

Adult↗
PubMed1988

Early morphological signs of embryonic genome expression in human preimplantation development as revealed by quantitative electron microscopy.

A quantitative electron microscopic analysis of human preimplantation embryos in conjunction with [3H]uridine labeling and light microscopic autoradiography revealed significant differences in the fractional volume of some cell organelles between the blastomeres of eight-cell embryos with fully activated extranucleolar and nucleolar transcription and those showing low extranucleolar and no nucleolar RNA synthesis, a pattern typical of four-cell human embryos. The latter type of blastomeres in eight-cell embryos did not show any significant quantitative cytological difference when compared to blastomeres of four-cell embryos. The phenotypical changes accompanying the overall enhancement of the embryonic transcriptional activity (increase in tubules/vesicles ratio and lysosomes, decrease in Golgi apparatus) were due to repartition of intracellular membranes amongst different types of organelles rather than to a noticeable change in the existing equilibrium between total membrane production and degradation.

Blastomeres↗
PubMed1988

Pregnancies after replacement of frozen-thawed embryos in a donation program.

Eighteen patients with primary (n = 8) or secondary (n = 10) ovarian failure were enrolled in a donation program. In 15 cases, the oocytes were donated anonymously; in 3 cases, they were donated by the sister of the recipient. All the recipients had cyclic steroid replacement therapy that included estrogens and progesterone administered by the transdermal and tranvaginal routes, respectively. The embryos obtained were cryopreserved and replaced with no attempt at synchronization between donor and recipient. Steroid hormonal patterns were within the range for the normal menstrual cycle and endometrial biopsies taken on day 21 or 22 of the treatment cycles were independently assessed as being representative of day 21 +/- 2. Four of 12 transfers were successful (31%): 1 patient aborted at 6 weeks, and the three others were delivered, one normally and two by cesarian sections. The authors' practice suggests the following: (1) steroid supplementation by transdermal and transvaginal routes is effective, (2) synchronization between donor and recipient is no longer required with the use of frozen-thawed embryos, and (3) the "temporal window" is large since all the replacements were done on day 14 of the cycle.

Administration, Intravaginal↗
PubMed1988

Cryopreservation of human embryos and oocytes.

The success rate of human embryo cryopreservation depends on technical and embryonic parameters. First of all, the cryoprotectant can affect embryo survival as we found by comparing two freeze-thaw procedures using propanediol (PROH) (1.5 mol) alone or with sucrose (0.1 mol). Embryo survival was significantly enhanced with sucrose (62 versus 32%). Embryo quality is another major parameter involved in the success of freezing; the rates of positive survival were found to be 67% for morphologically normal embryos versus 49% for embryos with fragments (P less than 0.001). The efficiency of embryo cryopreservation in an IVF programme could be estimated in 1986: a woman with extra embryos, stored after transfer of 3-4 fresh embryos (16% of all cycles), can expect a 22% pregnancy rate per transfer of fresh embryos and a 32% pregnancy rate per collection after transfer of the stored eggs. A comparative study of the cryopreservability of immature or mature oocytes was performed in humans. Human oocytes have a low survival rate (36%) whatever the cryopreservation protocol or the initial maturation stage. Immature human oocytes could survive freezing and thawing, mature and be fertilized in vitro, but with a very low efficiency.

Embryo Transfer↗
PubMed1988

Anonymous and non-anonymous oocyte donation preliminary results.

During the past year, we have developed an oocyte donation programme in 10 patients with complete absence of endogenous ovarian function (premature ovarian failure in seven cases, castration in two cases and Turner's syndrome in one case). In cases of anonymous donation, donors were volunteers devoid of any major genetical risk who were included in our IVF programme and who consented to donate one oocyte when at least seven oocytes were recovered, and two oocytes when at least 11 oocytes were recovered, to a recipient couple. As far as possible, morphological characteristics of both couples were paired. In cases of non-anonymous donation, donors were 'affective' donors, having at least one child. The resulting embryos after IVF of donated oocytes were either replaced directly in recipient women which required synchronization of the donor's and recipient's cycles, or cryopreserved and then thawed, usually at day 16 of recipient's artificial cycle, i.e. 2 days after introduction of the progestational compound. On the 10 patients entering this oocyte donation programme (20 cycles), 13 transfers were carried out resulting in four clinical pregnancies in three patients with premature ovarian failure and one with Turner's syndrome (20% pregnancy per cycle and 31% per transfer). Despite the small numbers, these good results prompted us to develop this protocol.

Adult↗
PubMed1988

Chromosome analysis of human oocytes and embryos: does delayed fertilization increase chromosome imbalance?

Thirty per cent of a sample of 120 unfertilized human oocytes carried chromosome abnormalities highly correlated with maternal age (38% in patients greater than 35, as compared with 24% in younger patients). Fertilized eggs, when observed 17 h after insemination, showed in 1.6% a single pronucleus suggesting parthenogenetic activation. In 92% of the cases two pronuclei were observed and the rate of chromosome anomalies depended on the morphological aspect of the embryos. Triploidy was also encountered in 6.4% of the eggs leading to an overall rate of chromosome aberrations reaching 29.2%. Delayed fertilization drastically increased the rate of chromosome anomalies (87%) as well as the rate of mosaicism: 30% versus 10.6% in timely fertilized eggs. The high rate of chromosome disorders in early life after in-vitro fertilization (IVF) raises the ethical question of the opportunity of carrying out a genetic control of normality in human embryos at the preimplantation stage.

Chromosome Aberrations↗