Gene activity and cleavage arrest in human pre-embryos

There is a high rate of spontaneous cleavage arrest around the four- to eight-cell stage of human development in vitro. Since this coincides with the time of activation of the embryonic genome it has been suggested that cleavage arrest may occur as a consequence of failure of gene activation. Gene expression in human pre-embryos is associated with an alpha-amanitin sensitive, qualitative change in protein synthesis. In order to ascertain the role of gene expression in cleavage arrest, we have examined the protein synthetic patterns of human pre-embryos which have undergone spontaneous cleavage arrest in vitro. Of 54 cleavage-arrested embryos, 27 demonstrated evidence of synthesis of proteins sensitive to alpha-amanitin, suggesting that cleavage arrest is not always accompanied by failure of activation of the genome. Our results would also suggest that activation of gene expression is simply related to neither cell number nor time spent in culture since fertilization, but may be related to continuing karyokinesis.

Reliability of detection by polymerase chain reaction of the sickle cell-containing region of the beta-globin gene in single human blastomeres

Human preimplantation embryos at various stages of development have been analysed using the polymerase chain reaction to amplify a 680 base pair fragment of the beta-globin gene. Successful amplification was achieved more frequently with DNA from intact embryos containing between one and 11 cells, single cumulus cells, oocytes which had failed to fertilize and polar bodies than from single blastomeres disaggregated from intact embryos and treated in an identical manner. The distribution of nuclei demonstrated using the nuclear chromophore diamino-phenyl-indole showed considerable inter-blastomere variation; however, no clear correlation between staining pattern and successful amplification was observed. The reason for the unreliable amplification of DNA from single blastomeres is unclear but this finding has important implications for preimplantation diagnosis of genetic disease.

Amnifiltration in the first trimester: feasibility, technical aspects and cytological outcome

An amnifiltration system has been developed which allows collection of cells from the amniotic sac in the first trimester of pregnancy whilst only removing 1 ml of amniotic fluid in total. The cells can be cultured and harvested, using the same methods as early amniocentesis, to enable prenatal diagnosis of fetal karyotype. A range of filters constructed from different materials and of differing pore sizes were examined for their ability to trap and subsequently release a maximum number of amniotic fluid cells. The best filter membrane was found to be a cellulose acetate filter of 0.8 micro m pore size. To achieve the same cytogenetic outcome as a 10 ml amniocentesis, a minimum of 20 ml amniotic fluid must be filtered and recirculated through the system.

A prospective study of the incidence, time of appearance and significance of anti-paternal lymphocytotoxic antibodies in human pregnancy

The incidence and natural history of serum anti-paternal cytotoxic antibody (APCA) in normal pregnancy and spontaneous abortion was investigated prospectively in 306 women (64 primigravidae and 242 multigravidae), in order to establish whether serum APCA is a useful screening test in the diagnosis, treatment and prognosis for patients with recurrent pregnancy loss. Pre-pregnancy, serial pregnancy and post delivery serum samples were tested against partner's lymphocytes, using a microdroplet lymphocytotoxicity assay. The incidence of serum APCA in the 256 pregnancies successfully completed was 32%, compared with 10% amongst the 50 pregnancies ending in spontaneous abortion. The lower incidence of positive APCA tests in unsuccessful pregnancies was explained by our finding that positive APCA tests are related to the gestational age of the pregnancy and are rarely demonstrable before 28 weeks gestation. Since APCA usually disappears between pregnancies, its usefulness as a diagnostic test for immunotherapy against recurrent abortion should be questioned.

Cryoprotection of human oocytes: inappropriate exposure to DMSO reduces fertilization rates

Human oocytes were exposed to the cryoprotectant dimethyl-sulphoxide (DMSO) at either 4 or 37 degrees C. Subsequent fertilization of these oocytes showed that exposure to DMSO at 37 degrees C was associated with a greatly reduced fertilization rate when compared to untreated control oocytes, whereas no such reduction was seen in oocytes exposed to DMSO at 4 degrees C. The significance of these results for the potential cryopreservation of human oocytes is discussed.

The incidence of abnormal morphology and nucleocytoplasmic ratios in 2-, 3- and 5-day human pre-embryos

Human cleaving pre-embryos at 2 and 3 days and cavitated pre-embryos at 5 days post-insemination have been examined for cell number and the incidence of mononucleated cells. At least 60% of polynucleate or anucleate cells have been detected at all these stages and regardless of morphological grading at day 2. It is concluded that even by the time at which pre-embryo replacement would occur therapeutically, the majority of pre-embryos are unlikely to have full developmental potential. The possible origins of the abnormalities of nucleocytoplasmic ratios are discussed.

Transient cooling to room temperature can cause irreversible disruption of the meiotic spindle in the human oocyte

The effect on the microtubule system of human oocytes of cooling to room temperature for either 10 or 30 minutes has been investigated. Changes in spindle organization were found in all oocytes cooled for 30 minutes compared with control oocytes kept at 37 degrees C throughout. These changes included reduction in spindle size, disorganization of microtubules within the spindle itself, and sometimes a complete lack of microtubules. In some oocytes, chromosome dispersal from the metaphase plate was associated with these changes. Cooling the oocyte to room temperature for only 10 minutes produced a similar pattern of disruption to spindle structure in many cases. The spindles in oocytes that were cooled for either 10 or 30 minutes and then allowed to recover at 37 degrees C for either 1 or 4 hours were found to resemble those in noncooled control oocytes in less than one half of the cases examined, although in only a few cases did the chromosomes remain dispersed. The significance of these findings for the handling of oocytes during gamete intrafallopian transfer and in vitro fertilization procedures is discussed in relation to the levels of aneuploidy detected in early human embryos.

Acid Tyrode's solution can stimulate parthenogenetic activation of human and mouse oocytes

Fresh and aged (24 hours after ovulation) human oocytes and recently ovulated mouse oocytes may be activated by exposure to acidified Tyrode's solution. No activation of either type of human oocyte was observed after exposure to hyaluronidase or pronase, but significant numbers of fresh mouse oocytes were activated after exposure to pronase but not to chymotrypsin. The implications of these results for the manipulation of human and mouse eggs in vitro are discussed.

Ectopic ovaries associated with absent uterus and pelvic kidney: CT findings

A patient with a congenitally absent uterus and a single pelvic kidney presented with recurrent pain in the left iliac fossa. This proved to be due to a prolapsed left ovary.

Measurement of HPRT activity in the human unfertilized oocyte and pre-embryo

The hypoxanthine phosphoribosyl transferase (HPRT) and adenine phosphoribosyl transferase (APRT) activities in individual non-fertilized human eggs and in human pre-embryos (4-cell to blastocyst stage) have been analysed. A wide spread of activities was observed, the mean values of which decline with time post-ovulation for both eggs and advancing pre-embryonic stages. The variation in activities was less in groups of eggs or pre-embryos recovered from a single ovulatory cycle. The activity of HPRT, but not of APRT, was readily detectable in single 4-cell and 8-cell blastomeres. When pre-embryos at various preimplantation stages were exposed to alpha-amanitin, to block transcription of mRNA from the pre-embryonic genome, no clear effect on HPRT activity was observed. It is concluded that the HPRT and APRT activities measured in the pre-embryos studied here are likely to be maternally inherited, and that use of a direct assay for HPRT activity for the pre-implantation diagnosis of Lesch-Nyhan disease would be premature.

Quality control in the IVF laboratory: in-vitro and in-vivo development of mouse embryos is unaffected by the quality of water used in culture media

We have examined the effect of media made with tap water or with various purified waters on the fertilization of mouse oocytes, their development to blastocysts, their rate of hatching in vitro and their survival after transfer to recipients. Zona-intact and zona-free embryos, as well as cell clusters from 8-cell stage embryos, were also used. The macromolecular composition of the media was varied. We were unable to find any adverse effect of tap water under any condition examined. The implications of these findings for quality control in IVF units are discussed.

Influence of past reproductive performance on risk of spontaneous abortion

OBJECTIVE

To investigate the incidence of spontaneous abortion in a population of women in order to establish their risk of spontaneous abortion and the obstetric factors predisposing to it.

DESIGN

Prospective study of women recruited by radio and poster appeal and from hospital outpatient clinics.

SETTING

English provincial community.

PATIENTS

630 Women from the general population intending to become pregnant.

INTERVENTIONS

The viability of the pregnancy was assessed by abdominal ultrasonography before completion of the eighth week, and the assessment was repeated if vaginal bleeding occurred.

MAIN OUTCOME MEASURE

Spontaneous abortion or live births in women with or without a previous history of spontaneous abortion.

RESULTS

The overall incidence of clinically recognisable spontaneous abortion before 20 weeks of gestation was 12% (50/407 pregnancies). The risk of spontaneous abortion in each category of patient was classified with respect to the patient's past reproductive performance and found to be influenced greatly by her previous obstetric history. In primigravidas and women with a history of consistently successful pregnancies the incidences of abortion were low (5% (4/87) and 4% (3/73) respectively), whereas women with only unsuccessful histories had a much greater risk of aborting the study pregnancy (24% (24/98)), even when their sole pregnancy had ended in abortion (20% (12/59)). The outcome of the last pregnancy also influenced the outcome of the study pregnancy; only 5% of women (5/95) whose previous pregnancy had been successful aborted, whereas the incidence of loss of pregnancy among women whose last pregnancy had aborted was 19% (40/214).

CONCLUSIONS

A knowledge of the patient's reproductive history is essential for the clinical assessment of her risk of spontaneous abortion. As the most important predictive factor for spontaneous abortion is a previous abortion, the outcome of a woman's first pregnancy has profound consequences for all subsequent pregnancies.

An evaluation of semen analysis and in-vitro tests of sperm function in the prediction of the outcome of intrauterine AIH

Twenty-nine couples with an average of 5 years of infertility were selected for treatment by intrauterine insemination of washed semen (AIH). The criteria for selection were (i) the female partner showed no detectable fertility disorders by routine screening; (ii) the male partner showed subnormal semen quality on conventional semen analysis. Ovulation was stimulated uniformly with clomiphene citrate and precipitated with human chorionic gonadotrophin (HCG). Inseminations were performed 31-32 h post-HCG, with the day of HCG determined by ultrasound monitoring of follicular development. The fertilizing capacity of the male partners' spermatozoa was tested in vitro using donated human oocytes and/or the zona-free hamster oocyte penetration assay. Up to eight cycles of AIH were alternated with cycles of natural intercourse. While no pregnancies occurred in the group during normal coital cycles, the AIH pregnancy rate was 17% per couple, but only 3% per insemination cycle. Four further pregnancies were achieved spontaneously in couples from the study group within 3 years of completion of the AIH therapy and four patients became pregnant following subsequent GIFT or IVF treatments. Neither of the in-vitro tests was helpful in predicting the outcome of AIH, spontaneous pregnancy nor of subsequent assisted conception procedures.

Are human spermatozoa separated on a Percoll density gradient safe for therapeutic use?

Motile morphologically normal human spermatozoa can be separated from semen by buoyant density centrifugation on Percoll (Pharmacia Fine Chemicals AB, Uppsala, Sweden) gradients. In this study, the authors have examined (1) the efficiency of washing procedures to remove contaminating Percoll particles from the separated spermatozoa, and (2) the potential of Percoll particles, which contain silica, to cause an inflammatory response when used for intrauterine insemination, or when introduced into the fallopian tube during gamete intrafallopian transfer (GIFT) procedures, as assessed by an intraperitoneal injection into mice. Although Percoll was phagocytosed at the injection site, and therefore cannot be presumed to be totally inert, no generalized inflammatory response was detected. A double spin and wash technique was found to remove most residual Percoll from the spermatozoa, as assessed by scanning electron microscopy. These results suggest that procedures involving the use of Percoll for the separation of human spermatozoa for in vitro fertilization, GIFT, or intrauterine insemination should include stringent washing protocols that will remove most, if not all, contaminating Percoll from the sample.

Cytoskeletal organization in fresh, aged and spontaneously activated human oocytes

The cytoskeleton of the human oocyte (microtubules and actin filaments) has been examined using fluorescence microscopy. In unfertilized oocytes in metaphase of the second meiotic division, microtubules were found exclusively within the spindle which was located at the periphery of the cell and oriented radially, with its long axis perpendicular to the surface membrane. The spindle was anastral and slightly pointed at each pole, the chromosomes being arranged on a metaphase plate at the equator. When treated with taxol, the oocyte spindle became astral and microtubules appeared in the cortex of the oocyte in the form of small strands or bundles. Polymerized actin was found to be present in a dense filamentous layer throughout the cortex of the unfertilized oocyte. Aged unfertilized oocytes displayed an increased incidence of disrupted or abnormal cytoskeletal organization. In parthenogenetically activated oocytes in anaphase and telophase, microtubules were again found predominantly in the spindle but in addition, cortical strands or bundles of microtubules were often present. Oocytes in late telophase sometimes showed the presence of a concentrated ring of actin in the cleavage furrow between the oocyte and the second polar body. Activated oocytes in early interphase contained a dense cortical mesh of microtubules and a midbody remnant between the oocyte and the polar body. The cytoskeletal organizations of mouse and human oocytes are compared.

The effect of morphology on the ability of human spermatozoa to penetrate zona-free hamster oocytes

The effect of morphology on the ability of human spermatozoa to penetrate zona-free hamster oocytes was investigated using fractions of individual semen samples enriched for morphologically normal or abnormal spermatozoa, after separation by buoyant density centrifugation on self-generating Percoll gradients. Using this separation technique, the percentage of spermatozoa of normal morphology is greater in the lowermost 1 ml of the Percoll column (layer 1) than in the fraction recovered from higher up the column. Thus it was possible to compare two populations of spermatozoa from each semen sample in their ability to penetrate hamster oocytes. After normalizing the concentration of motile spermatozoa the mean hamster oocyte penetration rate was significantly higher with spermatozoa recovered from layer 1 (39 +/- 4%) compared with those recovered from layer 7 (21 +/- 4%), which suggests that morphologically abnormal spermatozoa do not have the same fertilizing capacity as those with normal morphology.

The use of mouse preimplantation embryos for quality control of culture reagents in human in vitro fertilization programs: a cautionary note

Mouse embryos with their zonae pellucidae intact are more resistant to suboptimal culture conditions than are zona-free embryos. This observation questions the general practice of using zona-intact preimplantation mouse embryos to monitor the quality of media and reagents used in human IVF programs.

Retrograde ejaculation: a systematic approach to non-invasive recovery of spermatozoa from post-ejaculatory urine for artificial insemination

Retrograde ejaculation is an uncommon but treatable form of male infertility. Successful recovery of live spermatozoa from the post-ejaculatory urine for artificial insemination is dependent on careful regulation of pH and osmolarity of the urine into which ejaculation takes place, and separation of the motile spermatozoa from the debris and cells which are found in these samples. Three pregnancies established by artificial insemination of spermatozoa recovered by noninvasive means from the bladders of men suffering from retrograde ejaculation are described. The techniques for preparing the urine for spermatozoal survival, and for removal of cells and debris by sedimentation or buoyant density centrifugation are discussed.

Removal of bacterial contaminants from semen for in vitro fertilization or artificial insemination by the use of buoyant density centrifugation

Buoyant density centrifugation of semen produces the accumulation of populations of highly motile, morphologically normal spermatozoa in the lowermost 1 ml of Percoll (Pharmacia Fine Chemicals AB, Uppsala, Sweden) density gradients. In addition, the majority of bacteria present in semen are retained in the seminal plasma at the top of the gradients. Of 40 semen samples examined, 37 contained detectable bacteria, but after buoyant density centrifugation, the spermatozoal populations collected from the lowermost 1 ml of the Percoll columns were found to contain few or no bacteria. When preparations were collected using sterile technique (by boring a hole through the bottom of the centrifuge tube), 14 of the 20 preparations were found to be bacteria-free. When preparations were collected by passing a spinal needle from the surface through the seminal plasma to the bottom of the centrifuge tube, the sterility of the final spermatozoa preparations was not maintained, with only 5 of the 20 samples completely free of bacteria. The residual bacterial contamination of the remaining 15 samples was, however, very low (less than 5 colonies after a 48-hour culture period).

A regimen for obtaining mature human oocytes from donors for research into human fertilization in vitro

Patients awaiting laparoscopic sterilization were canvassed to allow oocytes to be aspirated from their ovaries at the time of operation for the purpose of testing the fertilizing capacity of spermatozoa from clinically infertile men. Because these patients were volunteers, the standard techniques for stimulation, ovulation prediction, operation, and oocyte recovery had to be modified for maximum safety and for convenience to both patient and staff. Superovulation was induced with 100 mg or 150 mg clomiphene citrate on days 2 to 6 or 5 to 9 of the menstrual cycle. Final maturation of oocytes was stimulated with 5000 IU of human chorionic gonadotropin administered between days 11 and 15 of the cycle, and the operation was performed 34 to 36 hours later on the routine gynecology operation lists. Of the 157 patients canvassed , 47% were willing to donate oocytes to the project. Despite the variability of the stimulation regimens, the simplified operative technique, and the fact that more than half the patients were on oral contraceptives in the previous cycle, one or more oocytes were retrieved in 75% of the patients. At the initial assessment, 83% of these were considered suitable for in vitro fertilization.

Preparation of human spermatozoa for in vitro fertilization by isopycnic centrifugation on self-generating density gradients

A simple and rapid method is described for the retrieval of highly motile, morphologically normal spermatozoa from human semen. This method is a modification of a technique described previously and employs the process of isopycnic centrifugation of semen on self-generating Percoll density gradients. The procedure is carried out under sterile conditions and has no detectable deleterious effects on the fertilizing capacity of spermatozoa. Spermatozoa may be recovered from semen samples of widely differing quality and can be used successfully for in vitro fertilization (IVF). This technique may be useful not only for the preparation of spermatozoa for IVF and possibly for artificial insemination by husband (AIH) but also for the investigation and analysis of the causes of infertility associated with oligozoospermia.

The transition from maternal to embryonic control in the 2-cell mouse embryo

The development of the early 2-cell mouse embryo to the late 2-cell stage is marked by the appearance between 23 and 26 h post-insemination of a complex of polypeptides of mol. wt. approximately 67 K. Addition of alpha-amanitin between 18 and 21 h post-insemination prevents or reduces the subsequent appearance of these polypeptides. Addition of alpha-amanitin after 21 h does not obviously affect the appearance of the approximately 67 K polypeptides. A major change in synthetic profile occurs between 29 and 32 h post-insemination involving many polypeptides. Addition of alpha-amanitin to 2-cell embryos prior to 29 h post-insemination prevents the appearance of the new polypeptides observed during this major change but does not prevent the disappearance of the old polypeptides. In contrast, addition of alpha-amanitin after this time does not affect the appearance of the new polypeptides. This result, together with other evidence presented, suggests that during the 2-cell stage the embryonic genome shows transcriptional activity in two phases at 18-21 and 26-29 h post-insemination, that these transcripts are utilized soon after their synthesis, and that most maternal transcripts used before the second phase of embryonic transcription become ineffective soon afterwards.

Time-dependent effects of α-amanitin on blastocyst formation in the mouse

Early compacting mouse morulae were placed in α-amanitin at various times after HCG and the effect of this transcriptional inhibitor during formation of the blastocyst was noted. No cavitation was observed in those embryos transferred into α-amanitin before 77 h after HCG but the percentage of cavitation increased dramatically in those embryos transferred after 80 h post HCG. The large increase in amino acid incorporation which normally occurs during formation of the blastocyst was blocked in those embryos placed in the inhibitor before 80 h post HCG. Two-dimensional polyacrylamide gel electrophoresis of radiolabelled embryos showed that the changes in synthesis of certain polypeptides normally associated with blastocyst formation did not occur in those embryos placed in α-amanitin before 80 h after HCG. Only one cleavage division appears to occur in the presence of α-amanitin. However, groups of embryos which had completed their fifth division before exposure to the drug subsequently were able to form blastocysts and showed the quantitative and qualitative changes associated with blastocyst formation despite the continued presence of the inhibitor. These results suggest that a critical transcriptional event concerned with blastocyst formation occurs around 80 h after HCG and may be associated with the fifth cleavage division.