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M Dhont

Publications and source records attributed to M Dhont.

At least 73 records · Page 4Linked to original sources
PubMed1998

Chromatin decondensation, pronucleus formation, metaphase entry and chromosome complements of human spermatozoa after intracytoplasmic sperm injection into hamster oocytes.

Obtaining karyotypes from human spermatozoa after microinjection into Syrian golden hamster oocytes is difficult and the hitherto reported results are unsatisfactory. This may be related to the injection and culture technique or to the high susceptibility of the hamster oocytes to undergo parthenogenetic activation or both. Therefore, we investigated the hamster oocyte-human sperm microinjection model using the following two approaches: (i) application of contemporary techniques for injection (touching the sperm tail) and culture (hamster embryo culture medium, HECM-3, 10% CO2) and (ii) omission of Ca2+ from the injection medium. Thus, in the first series of experiments, 252 hamster oocytes were injected with human spermatozoa. Among the 219 (87%) oocytes that survived the injection procedure, the mean percentages of male pronucleus formation [two pronuclei (2PN), two polar bodies (PB)], mitotic metaphase entry and sperm chromosome spreads were 41.4, 27.8 and 18.2% respectively. Analysis of the oocytes which failed to develop the male pronucleus following injection revealed that most of them had developed only the hamster female PN while the sperm nuclei were either intact or swollen (partially decondensed), indicating that failure of oocyte activation was not the likely reason for the failure of male PN formation in these oocytes. In the next series of experiments, sibling oocytes were alternately injected with spermatozoa suspended either in the regular (1.9 mM Ca2+) or Ca2+-free injection medium (experiment set 2, n=278). A significant improvement was noted in the mean percentages of oocytes with 2PN, 2PB, metaphase entry and sperm chromosome spreads in the Ca2+-free group versus the regular group (2PN, 2PB: 51 versus 36.6%, metaphase entry: 36.3 versus 26.9% and sperm chromosome spreads: 28 versus 20.4%; all P < 0.04). Thus, parthenogenetic activation appears to be one of the contributing factors for the failure of male PN formation after heterospecific hamster ICSI. From these experiments it can be concluded that application of the advanced injection and culture techniques and omission of Ca2+ from the injection medium are promising for the routine application of the hamster oocyte microinjection for karyotyping of human spermatozoa with poor fertilizing capacity.

Animals↗
PubMed1998

In-vitro maturation of human germinal vesicle stage oocytes: role of cumulus cells and epidermal growth factor in the culture medium.

In-vitro maturation (IVM) of oocytes is a promising technique to reduce the costs and avert the side-effects of gonadotrophin stimulation for in-vitro fertilization (IVF). The pregnancy rates from oocytes matured in vitro are much lower than those of in-vivo stimulation cycles indicating that optimization of IVM remains a challenge. Therefore, we investigated the effect of supplementation of the medium with gonadotrophins, oestradiol and epidermal growth factor (EGF) and the effect of retaining or removing the cumulus cells on nuclear and cytoplasmic maturation of immature oocytes. Human germinal vesicle (GV) oocytes obtained after gonadotrophin stimulation for intracytoplasmic sperm injection (ICSI) were cultured in a complex defined medium either supplemented with gonadotrophins, oestradiol and physiological concentrations of EGF (2 ng/ml) or gonadotrophins and oestradiol alone. The cumulus cells were either removed or kept intact. In GV stage oocytes cultured without cumulus (group I) significantly more oocytes reached the metaphase II (MII) stage at 30 h in media supplemented with EGF (64.3 versus 33.9%, P < 0.003). For oocytes cultured with intact cumulus (group II), more oocytes reached MII at 30 h than in group I, but there was no difference in medium with or without EGF supplementation (81.8 and 79.8% respectively). Cytoplasmic maturation of MII oocytes was judged from their capability to activate and fertilize after ICSI. In group I, the rates of activation and normal fertilization were similar. However, in group II, significantly more oocytes underwent normal fertilization in the EGF-supplemented than the unsupplemented group (71.7 versus 45.6%, P < 0.05). The cleavage rates of the fertilized oocytes were similar in the sibling oocyte subgroups cultured with or without EGF supplementation, but the overall cleavage rates were higher in cumulus-intact compared to cumulus-denuded oocytes (88.9 versus 47.8%, P < 0.001). Thus, supplementation of the maturation medium with EGF and maintenance of the cumulus during culture improve the nuclear and cytoplasmic maturation of human oocytes in vitro.

Adult↗
PubMed1998

Fertilization, pregnancy and embryo implantation rates after ICSI with fresh or frozen-thawed testicular spermatozoa.

This study aimed to determine whether fertilization and implantation rates after intracytoplasmic sperm injection (ICSI) with fresh or frozen-thawed testicular spermatozoa were comparable. Between 1 January 1996 and 31 December 1996, 65 ICSI cycles with testicular spermatozoa and 35 cycles with frozen-thawed testicular spermatozoa were carried out. In 50 out of 65 ICSI cycles, testicular spermatozoa could be retrieved and in 34 out of 35 cycles carried out with frozen-thawed testicular spermatozoa, motile spermatozoa could be recovered. The fertilization rate after ICSI with frozen-thawed testicular spermatozoa was significantly lower (71.1%; P < or = 0.008) than with fresh testicular spermatozoa (79.3%). The pregnancy rate was similar for both groups (38.2 and 26.5 %). The implantation rate per transferred embryo, however, was significantly lower in the frozen-thawed rather than in the fresh testicular sperm group (9.1 versus 24.6%; P = 0.001). The live birth rate per transferred embryo was also higher in the group in which fresh testicular spermatozoa were used (18.8 versus 7.9% P = 0.043). This retrospective study shows that is possible to achieve a high fertilization rate after ICSI with both fresh and frozen-thawed testicular spermatozoa but implantation and live birth rates per transferred embryo, however, are significantly lower after ICSI with frozen-thawed than with fresh testicular spermatozoa.

Cryopreservation↗
PubMed1997

Fertilization and pregnancy after assisted oocyte activation and intracytoplasmic sperm injection in a case of round-headed sperm associated with deficient oocyte activation capacity.

OBJECTIVE: To investigate a method of assisted activation of human oocytes for the treatment of infertility resulting from globozoospermia associated with deficient oocyte activation capacity. DESIGN: The mouse oocyte activation test was used to analyze the oocyte activation capacity of the sperm cells of a patient with globozoospermia. Fresh donor human oocytes were used for determining the most appropriate procedure for oocyte activation. SETTING: Infertility Center, University Hospital of Ghent. PATIENT(S): A couple with infertility resulting from globozoospermia. INTERVENTION(S): Intracytoplasmic sperm injection, assisted oocyte activation, and embryo transfer. MAIN OUTCOME MEASURE(S): Oocyte activation and fertilization rates, implantation, and pregnancy. RESULT(S): Deficiency in oocyte activation capacity was found in the sperm of a patient with globozoospermia. This deficiency was proven by the mouse oocyte activation test and was confirmed further by lack of activation of human oocytes after simple sperm injection. Only human oocytes that were injected with sperm and subjected to calcium chloride and ionophore treatment underwent activation. Transfer of embryos obtained by this procedure of assisted oocyte activation resulted in an ongoing pregnancy. CONCLUSION(S): Assisted oocyte activation of human oocytes is useful when globozoospermia is associated with absence of oocyte activation capacity in the sperm. These cases can be identified by the mouse oocyte activation test.

Adult↗
PubMed1997

Perinatal outcome of pregnancies after assisted reproduction: a case-control study.

PURPOSE: A matched case-control study of all pregnancies obtained after either IVF or ICSI was conducted to investigate the perinatal outcome. METHODS: Three hundred eleven singleton and 115 twin pregnancies obtained after assisted reproduction were studied. Controls were selected from a regional register and were matched for maternal age, parity, singleton or twin pregnancy, and date of delivery. RESULTS: No significant difference was observed for gestational age at delivery, birth weight, incidence of congenital anomalies, and incidence of perinatal mortality between ART (singleton and twin) pregnancies and spontaneous controls. ART twin pregnancies showed a higher incidence of preterm deliveries than control pregnancies (52 vs 42%; P < 0.05) and needed more neonatal intensive care (47 vs 26%; P < 0.05). CONCLUSIONS: From this case-control study it is concluded that the perinatal outcome of ART singleton pregnancies is not different from that in matched controls. ART twin pregnancies showed a higher incidence of preterm deliveries than control pregnancies and needed more neonatal intensive care.

Adult↗
PubMed1997

Vaginoplasty by inverted perineal and labia minora flaps-a retrospective study.

Absence of the vagina occurs most frequently in the Rokitansky-Küster-Mayer (RKM) syndrome. Since Küster has reviewed the literature in 1910 many techniques have been described to create a neovagina. We describe a technique in which both a part of the labia minora and of the perineal skin are used as flaps to cover the neovagina and report on the long-term outcome in a series of 16 patients with RKM syndrome treated with this technique. No intra-operative or immediate postoperative complications were recorded. The average depth of the neovagina was 8 cm, at the end of the operation and 1 year later. After 3 months the neovagina was completely lined with vaginal epithelium. In six out of 16 patients scar formation and polypoid formation was observed at the apex of the neovagina. This could be successfully handled by excision and coagulation in all six cases. Ten patients reported a satisfactory sexual life. The technique is simple and easy to perform. The anatomical result and sexual gratification was outstanding in two-thirds of the patients. We conclude that flaps derived from the genital region offer the most physiological tissue for construction of a neovagina.

Journal Article↗
PubMed1997

The GyneFix implant systems for interval, postabortal and postpartum contraception: a significant advance in long-term reversible contraception. International Study Group on Intrauterine Drug Delivery.

Intrauterine contraception has a number of important advantages over other forms of contraception and remains, therefore, an important method of birth control. However, side-effects and other drawbacks have reduced its overall acceptance. Also misconceptions and lack of updated scientific knowledge among the potential users and providers are major obstacles to the widespread use of intrauterine contraception. Ideally, an intrauterine device (IUD) should prevent pregnancy effectively, be well tolerated, not become displaced or expelled over time, cause a minimum of side-effects, be long-lasting, have a strictly local effect, and be easy to insert and remove. A group at the University of Ghent, Belgium, the International Study Group on Intrauterine Drug Delivery, has developed, since 1985, a totally new concept in order to improve current intrauterine contraceptive efficacy and enhance tolerance, by creating a harmonious relationship between the uterine cavity and the contraceptive 'foreign body'. The new concept (GyneFix) consists of a non-biodegradable suture thread made of surgical 00 monofilament polypropylene on which six copper tubes are threaded, providing a total surface area of 330 mm2. The upper and lower tubes are crimped onto the thread to keep the tubes in place. The upper extremity of the thread is provided with a knot which serves as an anchor. The knot is implanted in the myometrium of the uterine fundus with a specially designed insertion instrument, thereby permanently securing the device in the uterine cavity. Since the initial clinical investigations, over 10,000 woman years of experience and up to 10 years' follow-up in international multicenter, non-comparative and comparative clinical trials have been collected. The clinical material also included a large number of nulligravid and nulliparous women. Due to the design characteristics of the GyneFix and its anchoring in the uterine fundus, an optimal tolerance and almost complete absence of expulsion were obtained. The constant release of copper ions in the upper part of the uterine cavity results in the high effectiveness of the anchored device. The effectiveness is higher than in the high-load conventional copper IUDs which have a risk of becoming displaced, partially or totally expelled in 10% or more (nulliparous women), resulting in a significant number of accidental pregnancies. The absence of frame and, as a consequence, its flexibility, explain the low incidence of side-effects and the very low incidence of complications, such as pelvic inflammatory disease and ectopic pregnancies. This new concept could be a major step forward in the acceptance of intrauterine contraception worldwide and increase its popularity. This article reviews the experience with the new concept for interval, postabortal and postpartum contraception.

Abortion, Induced↗
PubMed1997

Prospective randomized study comparing human serum albumin with fetal cord serum as protein supplement in culture medium for in-vitro fertilization.

The use of human serum albumin (HSA) instead of fetal cord serum (FCoS) as protein supplement highly simplifies the preparation of culture medium for human in-vitro fertilization (IVF) but whether they are equivalent in sustaining embryo development is still controversial. We performed a prospective randomized study of patients undergoing IVF or intracytoplasmic sperm injection (ICSI) where embryos were cultured in Earle's balanced salt solution containing either 8% (v/v) FCoS or 0.4% (w/v) HSA as protein source. Fertilization rates, morphological embryonic quality and pregnancy rates were compared. A total of 2189 oocytes from 210 cycles were cultured in medium supplemented with HSA in patient group 1 and 2109 oocytes from 203 cycles in medium supplemented with FCoS in patient group 2. The fertilization rate, defined as the presence of two nuclei, for microinjected oocytes was similar in both patient groups (77.4 and 76.7%, respectively). The fertilization rate for inseminated oocyte-cumulus complexes was significantly higher in the HSA group than in the FCoS group (62.9 versus 53.8%, P < 0.025). The embryonic quality was significantly better after culture in medium supplemented with HSA than with FCoS (13.7 versus 9.9% morphologically excellent embryos, P < 0.001). Implantation rates per transferred embryo were not significantly different (22.5 versus 18.2%), but there was a significantly higher pregnancy rate per embryo transfer in the HSA group (45.7 versus 35.9%, P < 0.05, respectively). Non-evolutive pregnancy rates were significantly different (27.4 and 16.7%). Our data demonstrate that the use of human serum albumin as a protein supplement for culture medium in human IVF programmes is associated with improved embryonic quality and significantly higher pregnancy rates. For this reason as well as the additional benefits of being virus-free and being purified, HSA is preferable to FCoS for the preparation of culture media in human IVF.

Adult↗
PubMed1997

Sperm-associated oocyte-activating factor is released from the spermatozoon within 30 minutes after injection as a result of the sperm-oocyte interaction.

We have previously shown that sperm plasma membrane damage makes the sperm plasma membrane permeable and the sperm nucleus accessible for low molecular weight molecules such as eosin and dithiothreitol. In the present study, we investigated whether this damage is associated with a passive release of the sperm-associated oocyte activating factor (SAOAF) from the spermatozoon and, if so, its time sequence. In a first study, human oocytes remaining unfertilized after conventional in-vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) and freshly ovulated mouse oocytes were injected with a whole spermatozoon or a sperm head respectively. They were randomly allocated to one of three groups: oocytes in group 1 were injected with a spermatozoon immobilized or sperm head detached immediately prior to the injection; oocytes in group 2 were injected with a spermatozoon immobilized or sperm head detached 2-4 h before injection; oocytes in group 3 were injected with a spermatozoon or sperm head that had been subjected to heat treatment. The activation rate of oocytes injected with a spermatozoon or sperm head was the same for groups 1 and 2, and significantly higher than in group 3 (P < 0.001). In a second series of experiments, human oocytes remaining unfertilized after IVF or ICSI were injected with a sperm head that was subsequently removed from the ooplasm 20-30 min after injection. The activation rates were compared to that of oocytes injected with heat-treated spermatozoa which subsequently were removed from the ooplasm. We found that the removal of the spermatozoon 30 min after injection did not prevent oocyte activation. Our data indicate that the initial damage to the sperm plasma membrane induced at immobilization, although essential for the onset of sperm nuclear swelling after ICSI, does not by itself lead to the release of SAOAF from the spermatozoon. We postulate, however, that SAOAF is released during the sperm nuclear swelling phase, which is induced by the so-called sperm nucleus decondensing factor (SNDF) of the oocyte.

Animals↗
PubMed1997

Determination of the parent of origin in nine cases of prenatally detected chromosome aberrations found after intracytoplasmic sperm injection.

Prenatal cytogenetic analysis of 71 fetuses conceived by intracytoplasmic sperm injection (ICSI) resulted in the detection of nine (12.7%) chromosome aberrations including two cases of 47,XXY, four cases involving a 45,X cell line and three autosomal trisomies. Molecular analysis of the parental origin of the deleted or supernumerary chromosome was performed by using polymorphic microsatellite markers. Six cases involving a sex chromosome abnormality were found to be of paternal origin while the two trisomic cases that could be analysed were of maternal origin. Two cases involved the same infertile couple who had two consecutive ICSI pregnancies terminated because of a chromosome abnormality. The replaced embryos in both cases originated from a single batch of ICSI fertilized oocytes of which part was used to initiate the first pregnancy and part was cryopreserved and used to initiate the second pregnancy.

Chromosome Aberrations↗
PubMed1997

Triple colour fluorescent in-situ hybridization for chromosomes X,Y and 1 on spare human embryos.

The potential for implantation of human embryos obtained by in-vitro fertilization is presumably determined to a large extent by their chromosomal constitution but cytogenetic analysis of preimplantation embryos has been hampered by a number of practical and technical problems. With the advent of fluorescent in-situ hybridization (FISH) a practical method for numerical chromosomal analysis has become available. A limited amount of data has been obtained with FISH on human embryos using probes binding to chromosomes X, Y, 16, 18 and 13/21 combined or for chromosomes X and Y or 1 and 17. It was our purpose to extend these data by the combined analysis of chromosomes X, Y and 1 in spare human embryos. A short fluorescent in-situ hybridization procedure involving the simultaneous use of three deoxyribonucleic acid probes detected with red, green, and a mixture of red and green was used to determine chromosomal abnormalities in 116 spare embryos with a poor morphological score and/or displaying one or more multinucleated blastomeres. The majority of the embryos was obtained by intracytoplasmic sperm injection. Less than half of the embryos (n = 54) were diploid and only 39 of them were uniformly XY11 or XX11; two embryos showed a non-disjunction and 13 embryos were aneuploid. Of the remainder, 22 were mosaic, nine were either haploid, triploid or tetraploid and 12 embryos were classified as chaotic. The latter pattern was particularly frequent in multinucleated blastomeres. Our data are comparable with those obtained with FISH using other chromosomal probes and confirm that the majority of preimplantation embryos carry a numerical chromosomal defect. Aneuploidy for chromosome 1 does not appear to be more common in preimplantation embryos than is reported for other chromosomes. Although the high incidence of chromosomal anomalies is presumably biased by the fact that only embryos with a poor morphological score were analysed, it nevertheless indicates that natural selection is the foremost reason for the low implantation rates of human preimplantation embryos in in-vitro fertilization (IVF) programmes.

Chromosome Aberrations↗
PubMed1997

Two cases of Robertsonian translocations in oligozoospermic males and their consequences for pregnancies induced by intracytoplasmic sperm injection.

Two case histories are presented documenting structural chromosome abnormalities in infertile males. The abnormalities were detected only after application of intracytoplasmic sperm injection (ICSI) was repeatedly unsuccessful or resulted in an abnormal pregnancy. A mosaic Robertsonian translocation 45,XY,der(13;13)(q10; q10)/46,XY,t(13;13)(p10;p10), der(13p;13p) incompatible with normal offspring was found in a male with extreme oligozoospermia after three subsequent ICSI treatments were unsuccessful and one had resulted in a spontaneous abortion. A second case involved a Robertsonian translocation 45,XY,der(13;14)(q10;q10) which was detected in a male with extreme oligozoospermia after ultrasound abnormalities were found in an ICSI-induced twin pregnancy. Amniocentesis showed an unbalanced 46,XY,+13,der(13;14)(q10;q10) karyotype in one twin and a Robertsonian 45,XX,der(13;14)(q10;q10) karyotype in the other twin. Chromosome analysis of males with abnormal sperm characteristics is advised prior to ICSI.

Adult↗
PubMed1997

Transport-in-vitro fertilization/intracellular sperm injection: a prospective randomized study.

We performed a prospective randomized clinical trial to investigate whether long distance oocyte transport prior to an intracytoplasmic sperm injection (ICSI) procedure influences fertilization rates, embryo quality and/or embryo implantation rates. After informed consent, 100 infertile couples booked for ICSI treatment were randomized into two groups. In group 1 (n = 50), patients were stimulated and monitored in Rotterdam (The Netherlands), and oocyte retrieval, ICSI procedure and embryo transfer took place in Gent (Belgium). In group 2 (n = 50), patients were stimulated, monitored and punctured in Rotterdam and the oocytes were transported in their follicular fluid in an isothermic transport box to Gent, where the ICSI procedure and the embryo transfer took place. In both groups the stimulation and monitoring regimen, puncture technique, laboratory conditions and transfer policy were identical. In both groups, the number of fertilized oocytes (7.13 +/- 0.65 versus 5.53 +/- 0.60, P = 0.08), the number of transferred embryos (2.36 +/- 0.09 versus 2.40 +/- 0.11, P = 0.87) and the embryo implantation rate [20/113 (17.7%) versus 19/103 (18.4%), P = 0.89] was similar. In group 1, the number of retrieved oocytes was higher (10.83 +/- 0.95 versus 8.44 +/- 0.93, P = 0.05). The total score of the embryos obtained (18.90 +/- 1.73 versus 12.64 +/- 1.26, P = 0.01), the number of good quality embryos (4.63 +/- 0.49 versus 2.98 +/- 0.38, P = 0.02), the mean score of the transferred embryos (3.32 +/- 0.11 versus 2.94 +/- 0.13, P = 0.05) and the number of embryos available for cryopreservation (2.70 +/- 0.45 versus 1.48 +/- 0.38, P = 0.03) were significantly higher in group 1. Therefore, long distance transport of oocytes prior to ICSI does not affect oocyte fertilization and embryo implantation rates, although a negative effect on embryo quality cannot be excluded.

Adult↗
PubMed1997

Disintegration of chromosomes in dead sperm cells as revealed by injection into mouse oocytes.

Intracytoplasmic sperm injection of immotile (dead) ejaculated human spermatozoa has been carried out by several centres for the treatment of infertility caused by severe asthenozoospermia (necrozoospermia). No healthy pregnancies have been reported as yet, suggesting irreversible damage to sperm DNA, centrioles and/or other important structures. We investigated this hypothesis by injection of immotile human spermatozoa obtained from several male infertility patients into mouse oocytes and analysis of the oocyte activation rate and sperm chromosome integrity. Motile spermatozoa of the same sample were used as a control. The proportion of living spermatozoa among the immotile was also assessed in each sample and was related to the results of the mouse oocyte injection test. The oocyte activation rate after injection of immotile human spermatozoa into mouse oocytes was the same or only slightly lower than after injection with initially motile spermatozoa (87-100% versus 100% respectively). The rate of normal sperm chromosome spreads correlated significantly (r = 0.90, P < 0.05) with the proportion of living immotile spermatozoa in a given sample. It varied from 4 to 48% for samples containing respectively 8 and 40% of living spermatozoa. Most of the mouse oocytes injected and activated with immotile human spermatozoa were arrested during a prolonged period of time at the interphase of the first cell cycle (from 22 to 60%). Others underwent a delayed nuclear envelope breakdown but showed signs of abnormal structure of both male and female or only the male pronuclear chromosomes. Our data demonstrate an irreversible damage of chromosomes in dead ejaculated human spermatozoa and provide an experimental basis for recommending the use of testicular or epididymal spermatozoa for treatment of male infertility due to necrozoospermia.

Animals↗
PubMed1996

Factors affecting the role of the spindle during early response of mouse oocytes to ethanol stimulation.

Winston et al. ([1995] J. Cell Sci., 108:143-151) have shown recently that short (6 min) exposure of spindle intact oocytes from Swiss mice to 8% ethanol induced activation of most oocytes, while disruption of the spindles in these oocytes by nocodazole, before and during ethanol exposure, completely inhibited oocyte activation. We compared the activation rates (ARs) of nocodazole-treated and intact oocytes recovered from SJL and B6D2 F1 hybrid mice under the same experimental conditions. The difference between the ARs of nocodazole-treated and intact SLJ oocytes was about the same as reported for Swiss oocytes (2% vs. 82%, respectively). In contrast, this difference was minor for B6D2 oocytes (87% vs. 100%, respectively). Moreover, 41% of these oocytes underwent activation when the spindle was absent, not only before and during, but also 2 h after ethanol exposure. Shortened exposure (2 min) of B6D2 oocytes to ethanol, however, increased the difference in the ARs of nocodazole-treated and intact oocytes (18% vs. 67%, respectively). We conclude that at least two parameters affect the necessity of the presence of the spindle during ethanol exposure for the activation of mouse oocytes. They are the genotype of the oocytes and the duration of exposure to ethanol. Under one set of these parameters the presence of the spindle is absolutely necessary, while under the other the appearance of the spindle a few hours after ethanol exposure is sufficient to allow the activation of some oocytes.

Animals↗
PubMed1996

Changes of intracellular free calcium during intracytoplasmic sperm injection.

The present experiments were undertaken to investigate whether the procedure of intracytoplasmic sperm injection (ICSI) is associated with changes in the intracellular free calcium concentration ([Ca2+]i). [Ca2+]i was measured, using the calcium-sensitive dye fura-2, during and after impalement of mouse oocytes with an ICSI pipette and injection of a small amount of medium alone or of medium containing a normal human spermatozoon. Forty-five oocytes were injected with medium. Two different responses were observed: 20 of these cells showed a large increase of [Ca2+]i upon impalement; the other 25 cells did not show any change of [Ca2+]i, neither in the acute period nor in a late period 4 hr after impalement. All the cells that responded with an increase of [Ca2+]i subsequently lysed within the first 30 min following impalement, while all the cells with no [Ca2+]i change remained intact. This observation suggests that only traumatic impalement is associated with an increase of [Ca2+]i. Thirty-one oocytes were successfully, i.e., without subsequent cell lysis, injected with a normal mouse or human spermatozoon. In none of these cells could any acute or late change of [Ca2+]i be observed. The experiments illustrate that successful performance of the ICSI procedure, i.e., ICSI not followed by cell lysis, is not associated with changes of [Ca2+]i in mouse oocytes. This suggests that the ICSI technique, by itself, does not help in activating the oocyte via manipulation-induced changes of [Ca2+]i.

Animals↗