Cell adhesion molecules on the oocyte and preimplantation human embryo

The presence of cell adhesion molecules on human oocytes, earlyembryos, and pre-hatched blastocysts was examined by indirectimmunofluorescence and compared to the distribution found onfirst trimester villous placenta with the same antibodies. Sixintegrin subunits (3, V, ß1, ß3, ß4,ß5) were observed consistently throughout preimplantationdevelopment. Evidence was also obtained for the presence ofintegrin subunits 2, 4, L, ß2, and ß7 ona small number of oocytes. A more restricted developmental analysisof E-cadherin, ICAM-1, NCAM, and VCAM-1 demonstrated that thesecell adhesion molecules are also present on oocytes and earlyembryos. L-selectin was detected on oocytes but was not foundon 8-cell embryos. The oocyte and early blastomeres have complexsurfaces in which the integrin and CAM families are represented. cadherin/cell adhesion molecules/human embryo/immunofluorescence/oocyte     

Fertilization and early embryology: Polypeptide profiles of human oocytes and preimplantation embryos

The polypeptides that direct fertilization and early developmentuntil activation of the embryonic genome occurs, at the 4–8cell stage in the human, are exclusively maternal in origin,and are either synthesized during oogenesis or translated laterfrom maternal mRNA. Using sodium dodecyl sulphate—polyacrylamidegel electrophoresis and silver stain, we have visualized andcompared the polypeptides present in different populations ofhuman oocytes and cleavage stage embryos obtained after superovulationand insemination in vitro. Two polypeptide patterns were resolved,differing in the region of mol. wt 69 kDa. The distributionof these patterns showed no correlation with the ability ofindividual oocytes to achieve fertilization and develop normallyto the 8-cell stage.     

Supraphysiological estradiol levels do not affect oocyte and embryo quality in oocyte donation cycles.

BACKGROUND: The study aim was to determine whether supraphysiological estradiol (E(2)) levels reduce oocyte/embryo quality in oocyte donation cycles. METHODS: A retrospective analysis of 330 consecutive fresh oocyte donation cycles was performed in an assisted reproductive treatment programme between January 1996 and December 2000. Throughout the study period, oocyte donors and recipients followed a standard synchronization regimen that did not vary. A serum E(2) level (peak E(2)) was obtained from all oocyte donors on the morning of HCG administration. Peak E(2) values were grouped by 33rd percentile (group I, <1500 pg/ml; group II, 1500-3000 pg/ml; and group III, >3000 pg/ml). All embryo transfers were performed on day 3 after oocyte recovery. RESULTS: Comparisons between groups revealed no significant differences in the quality of oocytes retrieved, and in fertilization rates. Higher peak E(2) levels were directly correlated with a greater number of oocytes retrieved, embryos available for transfer and cryopreservation, and higher average embryo quality scores (P < 0.005). Compared with group I, group III had significantly higher embryo implantation rates (P < 0.05). CONCLUSIONS: Sustained supraphysiological E(2) levels do not adversely affect the quality of developing oocytes and embryos. On the contrary, elevated E(2) levels are associated with a larger number of oocytes and embryos and high-grade embryos for transfer/cryopreservation and, consequently, improved implantation rates.     

HMG is as good as recombinant human FSH in terms of oocyte and embryo quality: a prospective randomized trial

Previous studies have demonstrated that the use of recombinant human follicle stimulating hormone (rhFSH) for ovarian stimulation may be associated with a better outcome than human menopausal gonadotrophin (HMG), probably due to the absence of LH, higher FSH bioactivity and better quality of oocytes and embryos when rhFSH is used. Very few studies have examined the effects of different gonadotrophins on oocyte and embryo quality. In this prospective study, 40 women undergoing ovarian stimulation for intracytoplasmic sperm injection were randomized to receive a standard protocol of either HMG or rhFSH in down-regulated cycles. Prior to microinjection, each denuded oocyte was videotaped to assess nuclear maturity, morphology of zona pellucida, oocyte and polar body and the zona thickness, and diameters of oocyte and ooplasma. Fertilization and subsequent embryo development of each oocyte were followed. The embryologists were blind to the type of gonadotrophin each patient had received for stimulation. No significant differences were found between the two groups with regard to the demographic data, the ovarian responses and pregnancy/implantation rates. The percentage of metaphase II oocytes in the HMG and rhFSH groups were similar (86.9 versus 87.4% respectively). All other parameters assessing oocyte and embryo quality were also comparable between the two groups.     

Immunolocalization of the cellular adhesion molecules, intercellular adhesion molecule-1 (ICAM-1) and platelet endothelial cell adhesion molecule (PECAM), in human edometrium throughout the menstrual cycle

In the present study the presence and distribution of cellularadhesion molecules involved in leukocyte binding were investigatedin human endometrium. Endometrial biopsies (n = 45) were collectedfrom women at all stages of normal menstrual cycles. Consecutivecryostat sections of endometrium were immunostained with monoclonalantibodies to intercellular adhesion molecule-1 (ICAM-1) andplatelet endothelial cell adhesion molecule (PECAM) and haematoxylinand eosin. Primary antibody binding was visualized using a streptavidin–biotinsystem. Strong staining for PECAM was observed in endothelialcells of all vessel types and in focal areas of stroma includingsingle cells, small clusters and larger aggregates of cells.At menstruation, however, almost the entire stroma stained forPECAM which was temporally related to a massive influx of leukocytes.ICAM-1 staining, which was consistently less intense than PECAMstaining, was detected in vascular endothelial cells duringthe cycle, reaching a peak at menstruation. Unlike PECAM, ICAM-1staining did not occur consistently across all vessel types.Stromal staining for ICAM-1 was rare except at menstruation,when almost the entire stroma showed positive staining for ICAM-1.No glandular or luminal epithelial staining was detected foreither PECAM or ICAM-1. This study demonstrates that PECAM andICAM-1 are expressed on endothelial cells of veins, arteriolesand capillaries, and stromal cells within human endometrium.     

Fertilization and early embryology: CD44 is expressed throughout pre-implantation human embryo development

The cell surface glycoprotein CD44 has been demonstrated ina variety of cell types in embryonic and adult tissues. We haveestablished that CD44 is present on human oocytes, cumulus cells,early embryos and pre-hatched blastocysts by indirect immunofluorescence.We have also shown that CD44 is present on 8–11 week placentalstroma cells, but not on the trophoblast. These findings demonstratethat CD44 is present throughout preimplantation development,and that down-regulation occurs on the embryonic surface afterimplantation.     

The effect of propofol anaesthesia on oocyte fertilization and early embryo quality

Propofol, frequently used for i.v. induction of anaesthesia in assisted reproduction procedures, has been suspected of damaging oocytes. Concentrations of propofol have recently been shown to increase in follicular fluid during oocyte retrieval. Our study was designed to assess whether exposure to increasing concentrations of propofol has a measurable effect on in-vitro fertilization, cleavage and embryo development. A cohort of 130 women underwent i.v. anaesthesia using propofol and fentanyl. Time of anaesthesia from i. v. injection of propofol was measured, as were the doses of the two drugs. In 32 women expected to have more than 15 oocytes retrieved, first, middle and last oocytes were cultured separately. The mean time from i.v. injection to first follicle aspiration was 200 s. The mean time for the aspiration of each additional oocyte was 17.6 s. In 10 out of 11 cases where follicular fluid concentrations of propofol were measured, there was an increase from the first to the last follicle, but no difference was found in the ratio of mature to immature oocytes. Nor were any differences found in fertilization, cleavage and embryo cell number. In so far as in-vitro development reflects embryo quality, we conclude that the time elapsed between retrieval of the first and last oocyte does not affect oocyte quality.     

The concentration of inhibin B in follicular fluid: relation to oocyte maturation and embryo development

BACKGROUND: The objective of the present study was to investigate the correlation between inhibin B and estradiol levels in follicular fluid (FF) with the quality of subsequent embryo development from in-vitro fertilized oocytes aspirated from the same follicle. METHODS: A total of 156 infertile women undergoing controlled ovarian stimulation for IVF and embryo transfer was recruited to the present study. Prospectively, 233 FF samples and matched mature oocytes were studied. Concentrations of inhibin B and estradiol were determined by enzyme-linked immunosorbent assay (ELISA) and immunofluorometric assay (IFMA) respectively. RESULTS: Inhibin B levels in FF were significantly correlated with embryo scores on days 2 and 3 (48 and 72 h after oocyte retrieval). In contrast, both inhibin B and estradiol levels in FF were inversely related to age. Furthermore, FF inhibin B levels were inversely associated with serum FSH levels on day 3 of the menstrual cycle, which was believed to reflect the ovarian reserve. CONCLUSION: Inhibin B in FF may serve as an effective marker of follicular development and a useful predictor of quality of embryo. In addition, quality of oocyte is age-related and declines as age increases.     

Preiinplantation diagnosis: Ultrasound derived indices of follicular blood flow before HCG administration and the prediction of oocyte recovery and preimplantation embryo quality

The principal aim of the study was to relate ultrasound-derivedindices of blood flow in individual follicles on the day of,but before, the administration of human chorionic gonadotrophin(HCG) to the subsequent recovery of oocytes and the productionof preimplantation embryos. Data were obtained from 21 women(aged 29–43 years) with bilateral tubal occlusion, whowere undergoing treatment by in-vitro fertilization (FVF) andembryo transfer. Transvaginal ultrasonography with colour Dopplerimaging and pulsed Doppler spectral analysis were used to measurefollicular volume and derive indices of blood flow. The end-pointsfor each follicle were the volume, peak systolic velocity (PSV),pulsatility index (PI), and the recovery or non-recovery ofan oocyte, the subsequent production or non-production of apreimplantation embryo and the morphological grade of each embryo.A total of 94 follicles were studied; 74 oocytes were recovered(79%) and 40 embryos (33 grade I or II) were produced. Therewere four clinical pregnancies (pregnancy rate 25.0% per transfer,19.0% per patient). There was a significant correlation betweenwhether or not follicular blood flow was detected and whetheror not an oocyte was recovered (P <0.05, x² test). The valuesfor volume and PI were not clinically useful. The PSV (cm/s,mean ± SD) was higher in follicles that were associatedwith the production of an embryo (12.7 ± 5.9) comparedwith those that were not (8.5 ± 5.0; P <0.05, Student'st-est). The probability of producing a grade I or grade II embryowas 75% if the PSV was 10 cm/s. The corresponding value was40% if the PSV was <10 cm/s and 24% if blood flow was notdetected (i.e. PSV <3 cm/s). There was a significant increase(P <0.05, Student's t-test) in the PSV before aspirationin those follicles associated with the subsequent productionof an embryo. We conclude that the value for PSV, before theadministration of HCG, can be used to identify follicles witha high probability of producing an oocyte and a high grade preimplantationembryo. The information may also be used to time the administrationof HCG to achieve the optimum number and quality of embryosfor patient management.     

Immunology: Distribution of cell adhesion molecules on CD56++, CD3-, CD16- large granular lymphocytes and endothelial cells in first-trimester human decidua

Human decidua exhibits a unique infiltrate of large granularlymphocytes (LGL) with a natural killer (NK) cell phenotype(CD56++, CD16–, CD3–). The mechanisms underlyingthe binding of circulating LGL to vascular endothelium in thedecidua and their migration into the decidual stroma were investigatedimmunohistochemically in first-trimester decidua with antibodiesagainst endothelial adhesion molecules and their counter-receptorson leukocytes. Decidual and peripheral blood LGL were also investigatedby flow cytometry. In the immunohistochemical investigations,moderate to large numbers of lymphoid cells in the decidua werefound to express the ₄ and _L integrin subunits, platelet endothelialcell adhesion molecule (PECAM) and intercellular adhesion molecule-1(ICAM-1). PECAM and ICAM-1 were found on the endothelium oflarge numbers of decidual blood vessels of all types. Vascularcell adhesion molecule (VCAM), however, was found on the endotheliumof only small to moderate numbers of arterioles and venulesand a few capillaries, the latter being the main site of migrationof leukocytes into the stroma. Weak staining for endothelialleukocyte adhesion molecule (ELAM) was seen only in a moderatenumber of blood vessels. Flow cytometry revealed expressionof the _L integrin subunit by 72 ± 10% and 97 ±3% of decidual and peripheral blood CD56+ LGL, respectively,of the 4 integrin subunit by 85 ± 7% and 90 ±5%, of PECAM by 40 ± 12% and 30 ± 15%, and ofICAM-1 by 22 ± 10% and 1 ± 1%. These findingssuggest that interaction between the integrin _2L and ICAM-1is the more important mechanism of binding to endothelium inthe migration of CD56+ LGL out of the peripheral blood intothe decidua.     

Laser-assisted ICSI: a novel approach to obtain higher oocyte survival and embryo quality rates

BACKGROUND: Degeneration of oocytes occurs even when maximum care is exercised during ICSI, especially when the oolemma is very fragile and/or the zona pellucida is resistant. In order to be able to minimize the risk of degeneration associated with microinjection this study applied a new method: a microhole on the zona pellucida of the oocyte was drilled by laser beam just prior to ICSI to permit the penetration of the microneedle without any trauma. METHODS: A total of 32 patients (32 cycles) who had one or more previously failed ICSI cycles with a high degeneration rate of oocytes (>20%) were included in the study. Oocytes of the same patients were randomly divided into the study group [laser-assisted ICSI (LA-ICSI)] and the control group [conventional ICSI (C-ICSI)]. The outcomes of the cycles were compared and analysed. RESULTS: After LA-ICSI compared with C-ICSI, survival rates of oocytes were 99.6 and 84% (P < 0.0001), fertilization rates were 76.6 and 68.6% (not significant) and embryo development rates ( vertical line 6 cells on day 3) were 76.5 and 57.3% (P = 0.0024) respectively. CONCLUSIONS: Creating a microhole on the zona pellucida of the oocyte by laser beam prior to ICSI provides a less traumatic penetration of the injection needle into the ooplasm and results in lower degeneration and higher embryo development rates than C-ICSI in patients with fragile oocytes.     

Effects of in vitro oocyte maturation and embryo culture on the expression of glucose transporters, glucose metabolism and insulin signaling genes in rhesus monkey oocytes and preimplantation embryos

Glucose plays a fundamental role during oogenesis and embryogenesis, satisfying the metabolic demands of oocytes and embryos, providing for stored energy reserves in the form of glycogen and supporting nucleotide biosynthesis via the pentose phosphate pathway. Glucose also contributes to the production of amino acids, glycosylated proteins and extracellular components. A detailed understanding of the molecular mechanisms that mediate and regulate glucose uptake and metabolism at different stages of oogenesis and preimplantation embryogenesis could greatly benefit the development of improved methods for in vitro oocyte maturation and in vitro embryo production. Although these processes have been examined in a variety of rodent and agricultural species, detailed information has not yet been described for non-human primates. In this study, we examined the expression of the genes encoding glucose transporters, glucose metabolism enzymes and potential regulators of glucose metabolism in rhesus monkey oocytes and embryos. The data reveal stage-specific regulation of expression of specific types of glucose transporters, stage-specific changes in expression of genes related to different pathways of glucose metabolism and temporal changes in the expression of mRNAs related to insulin signaling. Additionally, the data reveal significant differences in expression of some of these genes in cultured embryos as compared with flushed embryos and between oocytes and embryos obtained following different hormonal stimulation and oocyte maturation protocols.     

The radiosensitivity of the human oocyte

BACKGROUND: We determined the best model available for natural follicle decline in healthy women and used this to calculate the radiosensitivity of the human oocyte. METHODS: Ovarian failure was diagnosed in six patients with a median age of 13.2 years (range 12.5-16.0) who were treated with total body irradiation (14.4 Gy) at 11.5 years of age (4.9-15.1). We previously estimated the dose of radiation required to destroy 50% of the oocytes (LD(50)) to be <4 Gy. This estimate is an oversimplification, because decay represents an instantaneous rate of temporal change based upon the remaining population pool, expressed as a differential equation: dy/dx = -y[0.0595 + 3716/(11780 + y)], with initial value y(0) = 701 200. RESULTS: Solving the differential equation, we have estimated the number of follicles left after irradiation given as sol(51 - s + r), where r equals age at treatment, s equals age at diagnosis of ovarian failure, and 51 years is the average age of menopause. The surviving fraction of oocytes as a percentage is 100 times this value divided by sol(r). The mean surviving fraction for the six cases is 0.66%. We obtain a function, g(z), which decreases in value from 100% at zero dosage to mean value at dosage z = 14.4 Gy. We have g(z) = 10(mx+c), where c = log(10)100 = 2, and m = [log(10)(0.66) - c]/14.4. Solving g(z) = 50 gives an LD(50) of 1.99. CONCLUSIONS: Based on new data and a revised mathematical model of natural oocyte decline, we have determined the surviving fraction of oocytes following irradiation and estimate the LD(50) of the human oocyte to be <2 Gy.     

Infertility: Beta-1 integrin cell adhesion molecules in the endometrium of fertile and infertile women

In order to investigate whether the endometrium of women withunexplained infertility differs immunologically from the endometriumof normal fertile women, a panel of six monoclonal antibodieswas used to characterize the presence of the ₁-integrins orvery-late-activation antigens (VLA) in the different endometrialcompartments. Precisely timed endometrial biopsies at 4, 7,10 and 13 days following the luteinizing hormone surge wereobtained from 24 normal fertile women (group I) and 24 womensuffering from unexplained infertility (group II). Frozen sectionswere labelled using an avidin-biotin peroxidase technique. VLA-1,VLA-2 and VLA-3 were present in glandular epithelium, stromalcells and vessels of both groups. VLA-4 was detected in groupI but was absent from glandular and surface epithelium of groupII. VLA-5 was not present in any of the specimens. VLA-6 wasidentified primarily in the basement membrane of vessels, glandularand surface epithelium in both patient groups. This study indicatesthat most ₁-integrins are present in endometrium throughoutthe luteal phase of the menstrual cycle. The differences observedbetween the two groups may contribute to unexplained infertility.     

Expression pattern of integrin adhesion molecules in endometriosis and human endometrium

Integrins are cell adhesion molecules that undergo cell-specific dynamic changes during the normal menstrual cycle in the human endometrium. Here, using immunohistochemistry, we have investigated the expression pattern of the integrins alphav, alpha2beta1, alpha3beta1, alpha3, alpha6, beta1, beta2 and beta3 in the human ectopic endometrium of 30 patients and in nine cases in the corresponding eutopic endometrium. The biopsies were obtained during the early or late follicular phase (25 cases), during the corpus luteum phase (four cases) and in one case after 6 months' treatment with a gonadotrophin releasing hormone (GnRH) agonist. The integrin expression was independent of the ovarian steroid situation at the time of biopsy. The integrin alpha6 was expressed in all endometriotic and endometrium samples. The integrin alpha3 was absent in all endometrium tissues of patients with endometriosis. However, the corresponding endometriotic lesions re-expressed this adhesion molecule in 15 cases. No change in integrin beta3 expression pattern could be demonstrated in either endometriotic lesions or endometrium samples, regardless of the menstrual cycle phase. A correlation between serum oestradiol and progesterone concentrations and the expression of the investigated integrins was not observed, thus indicating that these two hormones play a minor role in the regulation of the cell adhesion molecules examined. Our investigation suggests that endometriosis is a dedifferentiated disease as it expressed different integrins in comparison with the eutopic endometrium, and independently of the hormonal situation. The ability of endometriotic tissues to express integrins may explain the high recurrence rates in patients with endometriosis, as these samples retain their adhesion potency after retrograde menstruation and are thus able to establish cell-cell and cell-matrix interactions with the surrounding peritoneum.     

Human embryo cryopreservation, extrinsic and intrinsic parameters of success

Freezing and thawing (F-T) was applied to 490 early human embryosusing propanediol as cryoprotectant. The survival rate of embryosfrozen with propanediol alone did not exceed 31% (26/83). Thecombination of propanediol and sucrose, however, significantlyincreased the percentage of surviving (248/407 = 61%) and intact(188/407 = 46%) embryos and seemed to enhance embryo viabilityas suggested by the implantation rate (14.5 versus 8%) without,however, any statistical significance. Embryo survival, butnot viability, was correlated with morphological features, whereasneither the age of embryos (1, 2 or 3 days post-insemination)nor the segmentation stage (regular or intermediate) were involvedin F—T ability. Thirty-eight F—T embryos implantedwhen replaced in uterro, representing 8% of all F—T embryosand 14% of the F—T replaced embryos. The pregnancy rateper transfer reached 19% (35/185) and was identical to the pregnancyrate per transfer of fresh embryos (253/1149 = 22%). In oocytedonation, too, embryo freezing did not impair the pregnancyrate (25%). In spontaneous cycles, synchronous transfer gavebetter results than asynchronous transfers (20 versus 10%),but spontaneous cycles had no significant advantage (16% pregnaocy/transfer)as compared to stimulated (26%) and artificial (27%) cycles.     

Oocyte and embryo quality after coasting: the experience from oocyte donation

BACKGROUND: Oocyte donation provides us with an opportunity to study the clinical outcome of oocytes, retrieved from women undergoing coasting, in recipients in whom endometrial receptivity is unaltered by the coasting procedure. Thus, our aim was to describe oocyte donation outcome in donors undergoing coasting, the oocyte and embryo quality obtained from these cycles, and to determine the influence of coasting duration in the cycle outcome. METHODS: Matched-paired analysis included 15 oocyte donors with high response to ovarian stimulation and submitted to coasting and 15 oocyte donors with normal response to ovarian stimulation and not undergoing coasting. There were 38 oocyte recipients who shared oocytes from the donors under coasting and 37 from donors not undergoing coasting. RESULTS: Both groups of donors were comparable in terms of days and dose of ovarian stimulation, oocytes retrieved, metaphase II oocytes obtained, and in the appearance of ovarian hyperstimulation syndrome. Both groups of oocyte recipients were comparable in male-associated factor, pregnancy and implantation rates, as well as in embryo quality. Recipients from donors with coasting for >4 days had significantly lower implantation and pregnancy rates. CONCLUSIONS: the outcome of oocyte donation from donors undergoing coasting is not impaired, as good implantation and pregnancy rates are achieved. Embryo quality, according to our current standards, does not seem to be compromised by coasting itself. However, if coasting in oocyte donors is prolonged for >4 days there is a significant decrease in both implantation and pregnancy rates.     

Associations between ultrasound indices of follicular blood flow, oocyte recovery and preimplantation embryo quality

The aim of this study was to elucidate possible relationshipsbetween ultrasound indices of follicular blood flow, oocyterecovery and the subsequent production and morphological qualityof preimplantation embryos. A total of 27 women with bilateraltubal occlusion, undergoing treatment for infertility by in-vitrofertilization and embryo transfer, contributed data from 29cycles. Transvaginal ultrasono-graphy with colour Doppler imagingand pulsed Doppler spectral analysis was used to obtain indicesof blood flow for each follicle immediately before it was aspirated.The main outcome measures for each follicle were the pulsatilityindex, peak systolic velocity, recovery or non-recovery of anoocyte and the subsequent production or non-production of anembryo. A total of 126 follicles were studied, 102 oocytes wererecovered and 58 embryos (49 at grades I or II) were produced.There were six clinical pregnancies (pregnancy rate 27.3% perembryo transfer, 22.2% per patient). There was a significantcorrelation (P<0.0001, 2 test) between whether or not follicularblood flow was detected and whether or not an oocyte was recovered.The sensitivity of a test based on the presence of detectableblood flow and the subsequent recovery of an oocyte was 74%and the positive predictive value was 93%. The peak systolicvelocity (PSV, measured in cm/s, mean SD) in follicles withdetectable blood flow was significantly higher in folliclesthat were associated with the production of a preimplantationembryo (19.710.8) compared with those that were not (9.95.3,P<0.0001), Student‘s t-test). There was a 70% chanceof producing a grade I or II embryo if the follicular bloodvelocity was >10 cm/s, compared with 14% if the PSV was <10cm/s, or 18% if no blood flow was detected. We conclude thatthere is a physiological relationship between follicular bloodvelocity, oocyte recovery and the production of a high-gradepreimplantation embryo, which may form the basis of a usefulclinical test.     

Integrins are not involved in the process of human sperm-oolemmal fusion

BACKGROUND: We investigated whether integrins are required forthe human sperm–oocyte binding and fusion processes. METHODS:The expression of several integrin subunits at the human oocyteplasma membrane was investigated using immunofluorescence microscopy,and the functional role of integrins expressed at the humanoocyte surface in sperm–oocyte interaction was studiedusing a zona-free human oocyte binding and fusion assay. A totalof 144 unfertilized oocytes were stained with anti-integrinantibodies and 147 zona-free unfertilized oocytes were inseminatedin the presence of various anti-integrin antibodies that wereexpressed in oocyte plasma membrane. RESULTS: The antibodiesof six integrin subunits (₂, ₃, ₅, ₆, _V, _M) and six integrinsubunits (₁, ₂, ₃, ₄, ₅, ₆) were bound to the surface of fixedunfertilized oocytes. In contrast, the presence of ₁ and ₄ subunitscould not be verified. The human sperm–oocyte bindingwas only partially inhibited by blocking antibodies of ₂, ₃,₅, ₆, _V, _M, ₁, ₂ and ₃ with a maximum of 55% inhibition, butantibodies of ₄, ₅ and ₆ showed no effect on sperm–oolemmalbinding. A similar reduction of the number of fused sperm wasobserved. However, the ratio of fused sperm to total sperm (boundand fused) was not impaired by all integrin antibodies, suggestingthat integrins had no role in the sperm–oolemmal fusionprocess. CONCLUSIONS: These results suggest that one of thebinding mechanisms can be inhibited by integrin antibodies butthat this mechanism does not play an essential role in the humansperm–oolemmal binding and fusion processes. The othermechanisms, insensitive to integrins, may involve both bindingand fusion processes in human oocytes.     

The relationship between chromosomal abnormalities in the human oocyte and fertilization in vitro

The relationship between chromosomal abnormalities in the humanoocyte and fertilization in vitro was investigated by cytogeneticanalysis of an unselected population of oocytes, where failureto achieve fertilization was attributed to dysfunctional spermatozoa.The results demonstrated that 47% of such oocytes were chromosomallyabnormal. These data were used to calculate that the incidenceof chromosomal abnormalities in oocytes that do, and those thatdo not develop pronuclei following insemination in vitro is26.6% and 20.4% respectively. Statistical analysis demonstratedno relationship between chromosomal abnormality in the oocyteand its capacity to achieve fertilization in vitro.