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Y Menezo

Publications and source records attributed to Y Menezo.

At least 37 records · Page 2Linked to original sources
PubMed1994

[Assisted hatching and micro-fertilization].

Erbium-YAG laser has been applied for micromanipulation in human beings. In a first series of attempts it was used in the fertilization process for subzonal insemination (SUZI): laser assisted micromanipulation achieved significant higher fertilization rates (34.8%) when compared to mechanical SUZI (16.1%), and for partial zona dissection (PZD): in this case laser did not improve the results (laser 14.8% vs mechanical 14%). Erbium-YAG laser was used to assist hatching. In the mouse it significantly improved the hatching rate (80% vs 29.3%) 110 hours post hCG. This technique was applied in two different centres to patients with previous IVF failures. The implantation rate per embryo (14.4% laser assisted hatching vs 6% control group) and the pregnancy rate per transfer (40% vs 16.2%) were improved.

Animals↗
PubMed1993

Assessment of polyploidy in human morulae and blastocysts using co-culture and fluorescent in-situ hybridization.

Fluorescence in-situ hybridization with DNA probes for X, Y and no. 18 chromosomes was used to analyse human morulae (n = 13) and blastocysts (n = 41), obtained after co-culture on Vero cells. On the basis of the number of hybridization signals, the proportion of embryos with more than five polyploid cells was 30.8% for morulae and 29.3% for blastocysts. These values are similar to those for mixoploidy (mosaicism of diploid and polyploid cells) observed in blastocysts of animal species. The results were confirmed by scanning electron microscopy, which showed a wide variation in the size of blastocyst nuclei, and by classical cytogenetic analysis. Mixoploidy seems to be a normal feature in preimplantation embryos and to occur very early in human embryo development. This lays open to doubt the preimplantation diagnosis of genetic errors at these stages, since results obtained from single cell analysis may not be representative of the whole embryo.

Animals↗
PubMed1993

Effects of glucose and fructose on fertilization, cleavage, and viability of mouse embryos in vitro.

In this study we examined the role of glucose, and the use of fructose as a replacement, in embryo culture medium. Three embryo culture media were used: a routine embryo culture medium (M16), M16 without glucose (M16-G) and M16-G supplemented with fructose (M16F-G). Their effect on fertilization, rate of cleavage, and embryo viability were examined in both an outbred (OF1) and an inbred (C57Bl) mouse strain. Of the three media, only M16 was found to support fertilization. In vitro-fertilized embryos from OF1 oocytes and C57Bl oocytes and OF1 sperm were placed in the different media at the early 2-cell stage. In 65% of OF1 embryos cultured in M16, development was blocked at the 2-cell stage, whereas in M16-G and M16F-G embryos, only 22% and 32%, respectively, were blocked. M16F-G medium also produced morulae and blastocysts with higher cell numbers than M16-G. In vitro-fertilized C57Bl 2-cell embryos cultured in M16 displayed retarded cleavage to the 4-cell stage compared to embryos cultured in M16-G and M16F-G. In contrast, the morulae and blastocyst cell numbers were significantly lower in M16-G compared to M16 and M16F-G. The viability of morulae and blastocysts obtained from OF1 and C57Bl embryos cultured in M16-G and M16F-G was lower compared to control C57Bl morulae and blastocysts cultured in M16. The results show that although morphologically normal embryos could be obtained in M16-G and M16F-G, inherent anomalies existed that limited viability.

Animals↗
PubMed1993

[Cocultures: diagnostic and therapeutic value].

Results of french multiple collaborative studies are reported to evaluate the possible benefits of coculture in human IVF program. Prospective randomized study of IVF with transfer on day two versus IVF with transfer on day 6 shows that coculture does not improve overall results but leads to a reduction of triple or quadruple pregnancies. When applied to patients with more than 4 failures of embryo transfers on day 2, delayed transfer of blastocyst results in a high rate of clinical pregnancy (39%). Transfers of frozen-thawed blastocysts result in 17.8% ongoing pregnancies. Coculture is also a powerful tool for understanding early embryo development: when fertilization arises from sperm with poor characteristics or from frozen sperm of donor, embryo development appears to be altered: in these situations, rate of normally developing embryo is reduced and early embryo development becomes independent of fertilization rate.

Adult↗
PubMed1992

Coculture of embryos on Vero cells and transfer of blastocysts in humans.

Preliminary results are presented concerning the first clinical application of cocultures of human embryos. In the experimental group, the embryos were cultured and transferred on day 5 post-insemination. Blastocyst formation was not dependent upon the stimulation regimen. Long term or ultrashort stimulation of the ovaries after gonadotrophin releasing hormone analogue gave 55-60% blastocyst formation. Serum was not necessary to obtain blastocysts. When the embryos were cocultured, we observed an increase in the implantation rates per embryo in the pregnant patients. However, a real increase in the pregnancy rate per transfer was observed in a population of patients who had had repeated failures of embryo transfer. This observation is discussed as possibly bypassing an effect of uterine motility, but the overall beneficial effect has to be assessed in a double blind randomized study. It is probable that improvements will not be observed for all the indications for in vitro fertilization.

Animals↗
PubMed1992

In-vitro co-culture of early stage caprine embryos with oviduct and uterine epithelial cells.

Early stage caprine embryos were incubated with goat oviduct and uterine cells to evaluate whether these cells could be used as a somatic cell culture system to enhance development through the developmental block at the 8- to 16-cell stage during in-vitro culture. Following gonadotrophin treatment and natural mating, 2- to 4-cell embryos were surgically recovered from donor females for in-vitro culture studies. In Experiment 1, embryos were equally and randomly allotted to culture treatments of either culture medium plus caprine oviduct cells or culture medium alone. In both treatment groups, embryos were incubated in Medium-199 with 10% fetal bovine serum, 0.25% lactalbumin and 1% antibiotic-antimycotic at 37 degrees C in a humidified atmosphere of 5% CO2 in air. In Experiment 2, similar embryos were cultured in the same medium with either caprine oviduct cells, caprine uterine cells or sequentially incubated with oviduct cells and then uterine cells during a corresponding incubation interval. The culture conditions in Experiment 2 were the same as in Experiment 1. Following 72 h in culture, (Experiment 1), significantly more embryos developed through the in-vitro developmental block into blastocysts and hatched blastocysts when cultured with oviduct cells compared with no embryos developing through the in-vitro block when incubated with medium alone. In Experiment 2, caprine embryos co-cultured with oviduct cells alone resulted in more embryos developing into blastocysts and hatched blastocysts compared with those co-cultured with uterine cells alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Coculture of in vitro fertilized bovine embryos with oviductal epithelial cells originating from different stages of the estrous cycle.

Bovine embryos derived from in vitro fertilization procedures were cocultured in vitro with oviductal cells obtained from heifers between d 4 and 6 or d 14 and 16 of the estrous cycle. In addition, proteins secreted by oviductal cells isolated between d 4 and 6 or d 14 and 16 of the cycle were monitored. Embryos (2- to 4-cell) were incubated in Tissue Culture Medium-199 with 10% fetal bovine serum with or without oviductal cells at 39 degrees C for 10 d following in vitro insemination. There were more morulae, blastocysts, and hatched blastocysts following coculture with oviductal cells than with culture in medium alone. However, no differences were noted in embryo development following coculture with oviductal cells obtained between d 4 and 6 or d 14 and 16 of the estrous cycle. Also, no differences were detected in the amount of [35S]methionine-labeled proteins secreted by oviductal cells isolated from different days of the estrous cycle. These results indicate that oviductal epithelial cells isolated from early and late luteal phases of the estrous cycle will effectively support early embryonic development following prolonged in vitro culture.

Animals↗
PubMed1991

Movement characteristics and hyperactivation of human sperm on different epithelial cell monolayers.

Studies of sperm movement characteristics concern mainly sperm swimming between two glass surfaces (as in the Makler chamber). Using automated videomicrography, (CellSoft, Cryo Resources, New York, USA), we have analysed the movements of human sperm swimming on monolayers of different origins: monkey kidney (Vero) cells, bovine oviduct cells, and human endometrial cells. About 10(5) sperm were deposited upon preparations consisting of monocellular layers adhering to a coverglass, and placed in a deep slide-coverglass system. Experiments were first performed at room temperature then at 37 degrees C. At room temperature, motion characteristics on Vero cell layers (six samples) were not different from those measured in either the conditioned or corresponding non-conditioned media, except for the amplitude of lateral head displacement (ALH) which was significantly lower. Comparison of the three different cell monolayers showed no difference between them for the corresponding motion parameters. The data were dramatically different at 37 degrees C: sperm swimming on cell monolayers of genital origin (oviduct or endometrium) exhibited high rates of hyperactivation (HA: 36.7% and 38.6% respectively), which was significantly more than on either Vero cells (10.9%) or in a control medium (12.6%). Moreover, HA rates were significantly higher on genital cell monolayers than in the corresponding conditioned medium. Hyperactivated sperm exhibited lasting 'star-spin' trajectories rather than 'transitional phases'. It is concluded that passage of sperm on either oviduct or endometrial epithelial cell monolayers can induce sperm hyperactivation and improve their fertilizing capacity.

Animals↗
PubMed1989

Regulation of S-adenosyl methionine synthesis in the mouse embryo.

In early embryos, methylation is involved in "gamete imprinting" and inactivation of artificially introduced foreign genes. We studied the biosynthesis of the universal methylation cofactor: S-Adenosyl methionine (SAM). In the mouse, SAM conversion from methionine is limited by saturation of the methionine endogenous pool. SAM is present at a practically unchanged level from the unfertilized oocyte to early morula. SAM synthesis is increased at the time of compaction. In blastocysts, although methionine uptake is increased, the conversion rate from methionine is lowered. We observed no differences between C57 Black and Swiss albino random bred strains. In few experiments with human unfertilized oocytes and spared embryos, we observed higher methionine incorporation, and higher conversion to SAM. Next, the effect of two methylation inhibitors was tested, on early mouse embryonic development, at the one-cell and the two-cell stage. We found that ethionine is very toxic, even at the lowest tested concentration of 25 microM. Homocysteine is more potent at the one-cell stage than at the 2-cell stage, and it only partially blocks blastocyst formation from the 2-cell stage even at a concentration of 500 microM. It clearly acts as a methylation inhibitor; it lowers the SAM pool and the methylation index, SAH/SAM ratio (SAH: S-Adenosyl Homocysteine). We also found that homocysteine is an unexpected competitor for methionine influx and efflux.

Animals↗
PubMed1989

Culture of epithelial cells derived from the oviduct of different species.

This study proposes a procedure for the isolation and culture of oviduct epithelial cells of several species. In-vitro culture on such a feeder seems to allow full embryonic development and viability. The inner linings of Fallopian tubes from mouse, rabbit, cow and human were trypsinized and the epithelial cells were enriched with Percoll gradient. Isolated cells, obtained in high yield with good viability, were maintained in monolayer culture in B2-Menezo medium supplemented with serum, which also supports early embryonic development in vitro. The plated primary cultures reached confluence within 8 days, producing a monolayer of cohesive polygonal cells. Associated with this large epithelial cell population, ciliated cells as well as polykaryotic cells and few fibroblastic nests were observed. After the first sub-culture, the ciliated cells disappeared and the epithelial cell monolayer grew rapidly to confluence within 3 days and displayed contact inhibition. No epithelial cell growth could be obtained in culture in the absence of serum. The addition of oestrogens had no effect on any of the cultured oviductal epithelial cells. A spontaneous alteration was observed in morphology and growth after several passages, the number of which depends mainly upon the species.

Animals↗
PubMed1988

Viability and freezing ability of rabbit embryos collected in the vagina after prostaglandin treatment.

Morulae were collected from rabbit vaginas after prostaglandin treatment 65h post coitum. The optimum embryo recovery was obtained when the flushings started around 12h after the prostaglandin injection. The mean embryo collection was around 10 embryos per animal. These embryos had the same viability as those collected by the classical technique of uterine flushing (around 80%). The freezing ability of these embryos was also similar to that observed for uterus-collected embryos. Embryos not ejected after the treatment can develop in vivo and give birth to living progeny. The results obtained suggest that this technique can be used for egg transfer in rabbit genetic improvement programs.

Animals↗
PubMed1987

Enkephalin production by the corpus luteum.

In search of Early pregnancy factors, on the base of Kentsin, the sole molecule embryo-specific, we detected the presence of Enkephalin in the Mouse ovary, in Bovine and Human corpus luteum. In the Mouse the Met-Enkephalin release by the ovary seems to be stimulated by the oviduct in presence of the embryo. In vitro Met enkephalin release by Bovine Corpus luteum is about 0.5 to 1. pMole/mg of fresh tissue/24 Hours. This release is not increased in presence of trophoblastic tissue. The content of the fresh tissue is between 0.7 and 1.9 picomoles par gram of Human tissue, and 0.9 picomoles for Bovine tissue. We determine the presence of Leu-Enkephalin and Met-Enkephalin Arg-Gly-Leu. The ratios observed confirm a ProEnkephalin A expression in the Ovary. The roles of these opioid peptides is discussed in term of ovum transport, Granulosa cell physiology and Early pregnancy factors.

Animals↗
PubMed1987

Catecholamines within the rabbit oviduct at fertilization time.

Dopamine, norepinephrine and epinephrine levels of rabbit oviductal fluids were measured in order to establish whether the ampullary segment contained higher concentrations correlating with the sperm hyperactivity observed in the ampulla of different mammals. In this study, we found no statistically significant differences between flushings from the ampulla or the isthmus at oestrus, ovulation or 72 h post-coitum (p.c.). However, after correcting for the volume secreted, the concentrations of catecholamines are always lower in the ampulla than in the isthmus. In all cases the levels of biogenic amines were highest at oestrus then fell at ovulation. Individual variation of these levels at the time of ovulation was observed only in the ampulla, probably due to some contribution from follicular fluid. During the early luteal phase (72 h p.c.) the catecholamine levels again increase slightly, especially in the isthmus. We conclude that whiplash motility cannot be explained by a higher level of catecholamines in the ampulla.

Animals↗
PubMed1987

[Production of enkephalins by the human and bovine corpus luteum].

In search of early pregnancy factors, we detected by radioimmunoassay the presence of enkephalin in bovine and human corpus luteum. In vitro met-enkephalin release by bovine corpus luteum is about 0.5 to 1 pmole/mg of fresh tissue/24 hrs. The content of the fresh tissue is between 0.7 and 1.9 pmoles per gram of human tissue, and 0.9 pmoles for bovine tissue. Furthermore, we determined the presence of leu-enkephalin and met-enkephalin Arg-Gly-Leu to. The ratios observed confirm a pro-enkephalin A expression in the ovary. Opiates or opioid-like peptides are present in the female genitalia at the time of early embryo development. The roles of these opioid peptides is discussed in term of ovum transport, granulosa cell physiology and early pregnancy factors.

Animals↗
PubMed1987

[Fertilization in vitro. Perspectives for improving the technics].

Techniques of embryo cultures at an early stage, in spite of all the progress in that field, still present a major problem from the viability standpoint. The egg interrupts its segmentation, or, if it develops with an apparently normal chronology, the viability after transfer in vivo is very poor. Since a few years, trials in co-culture have been attempted. Culture on fibroblastic sheets gave disappointing results. As far as we are concerned, we have followed two different approaches: culture within the oviduct explanted in vitro and co-culture in the presence of embryonic tissue. The two types of co-culture give promising results, but it seems that the future lies in cultures on tubal epithelial cells. It will be necessary to obtain cellular lineage of these epithelia and to define culture media corresponding to the needs of the embryo as well as of these cells, since the embryo is an autonomous system, extremely sensitive to media alterations.

Animals↗
PubMed1986

Peptides bound to albumin.

Preparations of albumin (placenta or serum) do bind peptides. Dissociation of these peptides from the albumin core can occur partially in water but is much more efficient in the presence of amino acids and salts, in complex culture media for example. Contrary to common belief, we observed that arginine vasopressin (AVP) can bind to serum albumin, at least in commercial powder form.

Albumins↗