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[In vitro fertilization in male subfertility--micromanipulation and special techniques for semen preparation].

Poor semen quality is increasingly the reason for human infertility. For couples who cannot be helped by conventional in vitro fertilization (IVF) treatment, micromanipulation methods and special sperm preparation techniques in in vitro fertilization hold considerable promise to enhance fertilization of the egg. "Partial zona dissection" (PZD n = 59) or "subzonal insemination" (SUZI n = 36) were performed in 88 IVF cycles obtaining a fertilization rate between 12.2% and 34.8% depending on the micromanipulation technique applied and a pregnancy rate of 19.2% per embryo transfer. So far ten ongoing pregnancies have occurred and five healthy children have been born. In certain cases of male factor infertility micromanipulation and special sperm preparation techniques therefore represent the only possibility of conceiving.

Adult↗

Analysis of the chromosome complement in outbred mouse sperm fertilizing in vitro.

The chromosome complements in a population of mouse sperm from random-bred ICR donors were analyzed at first-cleavage metaphase after in vitro fertilization (IVF) of oocytes from females of the same strain. The sperm were aged as donations occurred within an average of 31 days, either since last mating or at arrival at the animal facility in the case of virgin males. Of a total of 598 sperm complements studied from 22 sexually mature males aged 10-26 weeks old, there was one diploid complement (0.17%). The frequencies of hyperhaploidy and structural aberrations that were studied in 338 complements were 4.4% and 3.6%, respectively, giving an overall frequency of 8.0%. The hyperhaploid complements consisted of n + 1, n + 2, n + 3, and n + 7 counts, while the structural abnormalities were of the chromosome type and included large and small fragments and a possible translocation. This is the highest frequency of sperm chromosome abnormalities reported for mouse sperm obtained from males under physiological conditions and fertilized in vitro or in vivo. Sperm aging, strain, and/or technique differences are among the factors that may be responsible for this high frequency. Since the 8.0% frequency of hyperhaploidy and structural abnormalities is similar to the frequency reported for human sperm after IVF, the outbred murine in vitro fertilization system may be a useful model to study the origin of human sperm chromosome abnormalities.

Aneuploidy↗

IVF: the new era.

In-vitro fertilization (IVF) has made great strides in the past 25 years including the development of micromanipulation techniques. Intracytoplasmic sperm injection (ICSI) for treatment of severe male factor infertility paved the way for the use of the micromanipulator. Micromanipulation techniques are now an integral part of an IVF program and are now also employed to biopsy embryos from patients harboring genetic abnormalities. Micromanipulation has also been used in the development of nuclear transfer techniques--a potential solution for creating "younger" oocytes for women of advanced maternal age and spermatozoa for azoospermic men. Other recent developments include the sequential media enabling the embryo to survive to blastocyst stage and also successful oocyte vitrification to preserve future fertility. This paper describes the latest technologies in in-vitro fertilization and relates them to the total problem of infertility, age-related and otherwise.

Embryo Transfer↗

Immediate ambulation after embryo transfer: a prospective study.

OBJECTIVE: To assess whether bed rest following the embryo transfer (ET) procedure contributes to the implantation process and pregnancy rate. DESIGN: A prospective (patient-influenced) study. SETTING: An in vitro fertilization (IVF) unit of an academic medical center. PATIENT(S): Four hundred six patients undergoing controlled ovarian hyperstimulation and IVF. INTERVENTION(S): All women undergoing in vitro fertilization-embryo transfer (IVF-ET) cycles in our unit were given a special individual counseling session before the ET procedure in which they were informed that our previous experience showed no advantage for bed rest over immediate ambulation after ET. The women were allowed to select the practice of their choice, and they were assured that their decision would have no influence on their further treatment. MAIN OUTCOME MEASURE(S): The stimulation pattern and cycle outcome were compared between the two groups (bed rest and immediate ambulation). RESULT(S): Of the 406 patients counseled during the study period, 167 preferred immediate ambulation and 239 opted to stay in the unit for 1 hour's bed rest. There were no significant differences between the groups in mean patient age, number of embryos transferred, and other variables of the assisted reproductive technique cycles. Pregnancy rates did not differ between the groups: 41 out of 167 (24.55%) in the immediate-ambulation group and 51 out of 239 (21.34%) in the bed-rest group. CONCLUSION(S): Immediate ambulation following the ET procedure has no adverse influence on the ability to conceive.

Adult↗

Polyspermic penetration in porcine IVM-IVF systems.

Although techniques for in vitro production of porcine embryos have proceeded very rapidly during the past decade, polyspermic penetration still remains a persistent obstacle to porcine in vitro fertilization (IVF) systems. Considerable research on in vitro polyspermic penetration in porcine in vitro-matured (IVM) oocytes has been undertaken to try to solve this problem. In the current paper, recent advancements in overcoming the problems of polyspermy in porcine IVF systems are reviewed. Partial induction of the acrosome reaction of boar spermatozoa in IVF media that contain caffeine is likely to be one of the major causes of polyspermy. A reduction in the number of incompletely acrosome-reacted spermatozoa, which can bind tightly to the zona pellucida and mask free sperm receptors of the zona pellucida, could reduce the incidence of polyspermic penetration; however, morphological differences in the reaction of the zona pellucida have been observed between IVM and ovulated oocytes, which suggests that altered zona morphology may be another cause of polyspermic penetration. It has been shown that the developmental ability of polyspermic porcine embryos to the blastocyst stage is similar to that of normal embryos but that developmental competence to term is much lower. To overcome the current problems of polyspermy, it is suggested that future efforts should be focused on controlling boar sperm function and/or sperm-zona binding to achieve the final maturation associated with normal zona modifications of porcine oocytes at fertilization.

Animals↗

Male-factor infertility and in vitro fertilization.

In vitro fertilization (IVF) was developed primarily as a treatment for female and idiopathic infertility. However, with the discovery that relatively few sperm are required to achieve fertilization in vitro, it was proposed that IVF could be used also as an effective treatment for male-factor infertility. This review deals with the work that has been carried out by various groups in this area of male-factor infertility. As the standards of classification and the presentation of results vary from group to group, this also shows that there is a need for some standardization of how patient selection and the presentation of results are carried out in the area of male-factor infertility.

Cell Separation↗

Fertility prognosis in IVF treatment of patients with cancelled cycles.

Among 429 patients admitted in our in-vitro fertilization (IVF) programme during the last 3 years, 106 experienced cancellation of one or more treatment cycles. A low oestrogen (E2) response represented by far the main reason for cancellation (144/184). Significantly lower clinical pregnancy rates were found in the group of patients with low E2-cancelled cycles (E2CC) as compared to the rest of the IVF population (13 versus 37%). Further comparison between these groups showed only little or no difference in the mean age of patients, basal FSH levels, number of egg collections, rate of oocytes obtained and fertilized per trial and mean embryonic vitality score. A large majority of E2CC patients were found to belong to the tubal infertility group (75%) as opposed to a lower proportion of tubal cases among other IVF patients (56%). E2CC tubal patients showed a lower pregnancy rate than other cases with abandoned cycles and also than other tubal patients (8.9 versus 25 and 35%, respectively). Mean numbers of previous laparotomies, of attempts at oocyte retrieval and of oocytes recovered per trial were similar in tubal patients with or without E2CC. However, in the E2CC tubal group mean age and basal FSH levels were somewhat higher, whereas E2 peak values and fertilization rates were lower, leading to a greater proportion of trials without embryo transfer. Embryonic scores and the E2/P ratio at day 3 of the luteal phase did not differ significantly. It may be concluded that cancelling of a cycle because of a low E2 response in a patient with tubal infertility is indicative of a poor prognosis in further IVF trials.

Adult↗

Case-based reasoning in IVF: prediction and knowledge mining.

In vitro fertilization (IVF) is a medically-assisted reproduction technique, enabling infertile couples to achieve successful pregnancy. Given the unpredictability of the task, we propose to use a case-based reasoning system that exploits past experiences to suggest possible modifications to an IVF treatment plan in order to improve overall success rates. Once the system's knowledge base is populated with a sufficient number of past cases, it can be used to explore and discover interesting relationships among data, thereby achieving a form of knowledge mining. The article describes the TA3IVF system--a case-based reasoning system which relies on context-based relevance assessment to assist in knowledge visualization, interactive data exploration and discovery in this domain. The system can be used as an advisor to the physician during clinical work and during research to help determine what knowledge sources are relevant for a treatment plan.

Artificial Intelligence↗

Different culture media requirements of IVF and nuclear transfer bovine embryos.

Important differences exist between in vitro fertilized (IVF) and nuclear transfer (NT) bovine embryos. Studies have shown that although in vitro development is comparable, post-implantation survival is greatly reduced in NT embryos. In this study, we compare serum and bovine serum albumin (BSA) supplementation during oocyte maturation and embryo culture of IVF and NT embryos. In experiment 1, oocytes and embryos were randomly distributed into different treatment groups consisting of synthetic oviductal fluid (SOF) medium supplemented with either serum, fatty acid-free BSA (FAF) or fraction V BSA during maturation and/or culture to assess IVF embryo development. In experiment 2, oocytes were matured in SOF + serum or SOF + FAF and reconstructed embryos were cultured in SOF + FAF to assess NT embryo development. Among the IVF treatment groups, a greater number of blastocysts were observed in the steer serum (SER) group (IVM and IVC in SOF + serum) on day 6; however, no significant differences were seen in blastocyst development from day 8 onwards. Hatching frequencies on days 8 and 9 were significantly greater in groups with serum, with the exception of FAF (IVM and IVC in SOF + FAF) on day 9. For the NT treatment groups, the presence of serum during IVM resulted in a higher proportion of MII oocytes and increased blastocyst development and hatching rates were compared with supplementation of FAF. These results indicate that both serum and FAF provide comparable embryo development for IVF but not for NT bovine embryos.

Animals↗

Cryopreservation of human ovarian tissue.

New and often aggressive treatment schemes allow the successful healing of many young patients with cancer, but the price the young women have to pay is high: many of them lose ovarian function and fertility. Due to the improved long-term survival of adolescents and young women with malignancies undergoing gonadotoxic chemotherapy, preservation of future fertility has been the focus of recent ubiquitarian interest. A feasible solution is the cryopreservation of ovarian tissue. Ovarian tissue, after thawing, can be used in three different ways: 1. grafted into its normal site (orthotopic); 2. grafted into a site other than its normal position (heterotopic), necessitating recourse to in vitro fertilization (IVF); 3. grown and in vitro matured in order to obtain metaphase II oocytes for an IVF program. It is believed that protein supplementation, in cryopreservation solution, is essential for improving ovarian tissue cryopreservation. The aim of this study was to evaluate the ultrastructural appearance of human ovarian tissue cryopreserved in 1.5 M 1,2 propanediol (PROH), 0.2 M sucrose using different protein sources: fetal calf serum (FCS), plasmanate or syntetic serum substitute (SSS). Fresh and frozen/thawed ovarian tissues were compared by transmission electron microscope (TEM), to evaluate the appearance of stromal and follicle cells as affected by different protein sources. Our data indicate that FCS is a better protein support for ovarian tissue cryopreservation when compared to SSS or Plasmanate. In addition the follicles are more resistant to the cryopreservation with respect to stroma.

Adolescent↗

Effect of preincubation of cryopreserved porcine epididymal sperm.

Preincubation of spermatozoa is important for capacitation and successful fertilization in vitro. The effects of preincubation time on frozen-thawed boar epididymal spermatozoa as measured by sperm motility, acrosomal integrity and fertilization ability in vitro were examined. Epididymal spermatozoa were collected from three Large White boars and frozen. The thawed spermatozoa were preincubated for 0, 15, 30, 60 and 120 min. Their motility was evaluated by a sperm motility analyzer and then the sperm motility indexes (SMIs) were calculated. The status of their acrosomal integrity was evaluated by triple-staining. Then, their fertilization ability was examined by in vitro fertilization (IVF) using porcine oocytes matured in vitro. SMIs of spermatozoa and the incidences of acrosome-intact live spermatozoa from the three boars were high (21-39 for SMI and 50-61% for acrosome-intact live spermatozoa) just after thawing, but both decreased as the duration of preincubation was prolonged (2-10 and 23-40%, respectively). The incidences of sperm penetration were high (61-89% of inseminated oocytes) when the sperm were preincubated for 0-60 min. However, sperm penetration decreased as the preincubation period was prolonged to 120 min. The degree of this decrease differed depending upon the boar from which the spermatozoa were obtained (10-72%). When the two parameters, sperm motility and acrosomal integrity, were analyzed statistically, the latter parameter rather than the former one showed a significant effect on penetration ability in vitro after each duration of preincubation. These results suggest that preincubation of frozen-thawed boar epididymal spermatozoa is not required for IVF and also that the maintenance of acrosomal integrity in unreacted status, rather than the maintenance of sperm motility, is important for fertilization ability after thawing and during preincubation of boar epididymal spermatozoa.

Acrosome↗

Glass wool column filtration of human semen: relation to swim-up procedure and outcome of IVF.

The number and viability of spermatozoa recovered by glass wool column filtration and a swim-up procedure were compared using different types of ejaculates, such as normal, asthenozoospermic and very viscous oligozoospermic semen. The filtration procedure resulted in significantly (P less than 0.01) higher recovery of viable spermatozoa than the swim-up procedure from all types of ejaculates studied. Further, the spermatozoa from 50 (78.1%) of the 64 ejaculates filtered through glass wool column fertilized at least one intact human egg in an in-vitro fertilization (IVF) procedure. It is concluded that glass wool column filtration is superior to the swim-up procedure since it yields a higher recovery of viable spermatozoa that are potentially fertile. Therefore, the glass wool column filtration procedure used to prepare spermatozoa may be of benefit for IVF, intra-uterine insemination, in-vitro fertilization and GIFT (gamete intra-Fallopian transfer), especially in cases of poor quality semen.

Cell Separation↗

Effect of in vitrofertilization medium on the acrosome reaction, cortical reaction, zona pellucida hardening and in vitro development in pigs.

Physiological events at the time of fertilization of pig oocytes may differ in vitro depending on the in vitro fertilization (IVF) medium. This hypothesis was tested by in vitro maturation of pig oocytes for 44 h in NCSU-37 medium and thereafter fertilization with frozen-thawed ejaculated spermatozoa. Three different IVF media (TCM-199, Tyrode's albumin lactate pyruvate (TALP) and Tris-buffered medium (TBM)) were used. For the acrosome reaction test, spermatozoa were incubated for 0-150 min in the three IVF media, and the proportion of live acrosome-reacted and acrosome-intact cells was determined by fluorescein isothiocyanate-labelled peanut agglutinin (FITC-PNA) and propidium iodide (PI) staining. The cortical granule density of oocytes was evaluated by confocal microscopy, 2.5 and 5.0 h after culture in each medium in the presence or absence of spermatozoa. Zona pellucida resistance to pronase digestion was also determined in the same groups. The percentages of penetration, monospermy, male pronucleus formation, cleavage and blastocyst formation, and the number of cells per blastocyst after culture were determined. The results indicate that the acrosome reaction occurred much faster in TBM than in TCM-199 or TALP medium. Continuous cortical granule synthesis was observed in the three media when oocytes were incubated in the absence of spermatozoa. The presence of spermatozoa triggered the cortical reaction in a large proportion of oocytes fertilized in TCM-199 and TALP media. On the basis of the duration of pronase digestion, the zona pellucida of oocytes incubated in TCM-199 was harder (407.7 +/- 35.5 s) than that of oocytes cultured in TALP (235.4 +/- 18.2 s) or TBM (189.1 +/- 16.8 s). No zona pellucida hardening was noted in oocytes after insemination in any of the media. The percentages of penetration and cleavage were higher in oocytes cultured in TCM-199 and TALP than in TBM. The percentage of monospermy was higher in TCM-199 and TBM than in TALP. No effect of the medium was shown on the percentage of blastocyst formation or on the number of cells per blastocyst. In conclusion, the results highlight how differently the fertilization events take place in each IVF medium and how far these IVF media still are from achieving biological properties of gametes close to those observed in the physiological setting.

Acrosome Reaction↗

The relative success of gonadotropin-releasing hormone analogue, clomiphene citrate, and gonadotropin in 1,099 cycles of in vitro fertilization.

OBJECTIVES: To evaluate the effectiveness of and analyze the factors influencing the outcome of three ovarian stimulation protocols used during in vitro fertilization (IVF) in a large population. DESIGN: Retrospective file review. SETTING: In vitro fertilization program in one center during the years 1985 to 1990. PATIENTS AND PROTOCOLS: Three hundred forty-one patients received clomiphene citrate (CC) and human menopausal gonadotropin (hMG), 365 received hMG alone, and 393 received gonadotropin-releasing hormone analogue (GnRH-a) for pituitary suppression followed by hMG stimulation. MAIN OUTCOME MEASURE: Rates of cancellation, total pregnancies, and ongoing pregnancies, with breakdown by age of patients. RESULTS: The cancellation rate because of early luteinization following GnRH-a/hMG was significantly reduced compared with the other two protocols: 3.6% versus 9.4% and 13.7% for CC/hMG and hMG, respectively. However, in women over 40 years of age, GnRH-a/hMG resulted in the highest rate of poor ovarian response. Significantly more oocytes were retrieved, fertilized, and cleaved after the use of GnRH-a/hMG compared with the other two protocols. Despite this, clinical pregnancy rate (PR) was the highest with CC/hMG compared with GnRH-a/hMG and hMG:31.4% versus 16.9% and 15.7%, respectively. Ongoing PRs were 20.5%, 9.7%, and 11.6%, respectively. CONCLUSIONS: Although the use of GnRH-a for pituitary suppression before ovarian stimulation for IVF reduced the cancellation rate and increased the number of retrieved oocytes, it was not found to result in higher PRs than those achieved by stimulation with CC/hMG. This suggests that treatment by GnRH-a/hMG should be reserved mainly for the prevention of early luteinization.

Clomiphene↗

Laser assisted hatching in good prognosis patients undergoing in vitro fertilization-embryo transfer: a randomized controlled trial.

OBJECTIVE: To evaluate whether assisted hatching improves clinical outcomes of embryo transfers to good prognosis patients, defined as patients < or =39 years with normal follicle-stimulating hormone (FSH) and E(2) levels, no more than one previous unsuccessful cycle of in vitro fertilization (IVF)-embryo transfer, and good embryo quality. DESIGN: Prospective randomized controlled trial. SETTING: Private assisted reproductive technology (ART) center. PATIENT(S): One hundred ninety-nine good prognosis patients undergoing IVF-embryo transfer. INTERVENTION(S): In vitro fertilization followed by embryo transfer on day 3 after oocyte retrieval with or without assisted hatching using a 1,480-nm wavelength infrared laser. MAIN OUTCOME MEASURE(S): Clinical intrauterine pregnancy, spontaneous pregnancy loss, and live birth. RESULT(S): Rates of clinical intrauterine pregnancy with fetal cardiac activity (53% vs. 54% per cycle), spontaneous pregnancy loss (13% vs. 16% per pregnancy), and live birth (47% vs. 46% per cycle) were very similar between treatment cycles with laser-assisted hatching and control cycles in which embryos were transferred without assisted hatching. There were no significant differences between treatment and control groups in any measured clinical outcome parameters. CONCLUSION(S): Assisted hatching does not improve clinical outcomes among good prognosis patients.

Adult↗

Coping mechanisms in patients presenting for in-vitro-fertilization.

OBJECTIVES: The purpose of this study was to assess the coping mechanisms in patients presenting for in-vitro fertilization (IVF). METHODS: We evaluated thirty consecutive couples presenting for in-vitro-fertilization. All couples were interviewed individually at first, and then together, using a semi-structured interview technique. Psychiatric diagnoses were made using the Diagnostic and Statistical Manual-IV (DSM-IV) criteria. Coping mechanisms used by the individuals were assessed using the Mechanisms of Coping Scale (MOCS). Other instruments used were Hamilton Depression Rating Scale (HAM-D-17), Hamilton Anxiety Rating Scale (HAM-A), Brief Psychiatric Rating Scale (BPRS), Self-Rating Symptom Scale (SRSS), and Eysenck Personality Inventory (EPI). RESULTS: The mean age of the sixty patients was 32.3 +/- 5.2 years. Fatalism was the commonest factor on the mechanisms of coping scale. Analysis of variance (ANOVA) across all factors of the MOCS for demographic factors showed that men used problem-solving mechanisms significantly more often than women (F = 3.0, df = 1, 58, p < 0.05). ANOVA across coping factors on stressors with post-hoc tests of significance revealed that individuals facing social stress used fatalism significantly more often than other coping mechanisms, while those facing career stress used problem-solving significantly more often than other coping mechanisms (F = 5.6, df = 1, 58, p < 0.05 and F = 3.04, df = 1, 58, p < 0.01 respectively). ANOVA across coping factors on HAM-D-17 scores revealed that individuals who used fatalism had significantly higher HAM-D-17 scores compared to those who did not (F = 4.4, df = 1, 58, p < 0.05). ANOVA across coping factors on HAM-A scores revealed that individuals who used escape-avoidance had significantly lower HAM-A scores than those who did not (F = 4.3, df = 1, 58, p < 0.05). ANOVA across coping factors on SRSS scores revealed that individuals who used passivity or fatalistic coping mechanisms had significantly higher scores on SRSS than who did not (F = 4.6, df = 1, 58, p < 0.05 and F = 3.5, df = 1, 58, p < 0.05). CONCLUSIONS: Differential patterns of coping were found among the sixty individuals presenting for IVF and were associated with a variety of factors including gender, education, stressors, and levels of depression, anxiety, and overall psychopathology. Efforts to recognize and recruit the coping mechanisms of infertile individuals are likely to enhance their ability to participate effectively in treatment.

Adaptation, Psychological↗

Successful piglet production after transfer of blastocysts produced by a modified in vitro system.

Porcine in vitro production (IVP) systems, including in vitro maturation (IVM) and in vitro fertilization (IVF) of oocytes and their subsequent in vitro culture (IVC), have been modified by many researchers, but are still at a low level because of a low developmental rate of embryos to the blastocyst stage and their poor qualities. Our objectives were to establish reliable IVP procedures for porcine blastocysts and to examine the ability of the blastocysts to develop to term after transfer to recipients. Porcine cumulus-oocyte complexes were matured in vitro under 5% O(2) or 20% O(2), fertilized in vitro under 5% O(2), and subsequently cultured under 5% O(2) in 1) IVC medium supplemented with glucose (IVC-Glu) from Day 0 (the day of IVF) to Day 6; 2) IVC-Glu from Days 0 to 2, then IVC medium supplemented with pyruvate and lactate (IVC-PyrLac) from Days 2 to 6; 3) IVC-PyrLac from Days 0 to 2, then IVC-Glu from Days 2 to 6; and 4) IVC-PyrLac from Days 0 to 6. There were no significant differences in blastocyst formation rates on Day 6 between the 5% O(2) and 20% O(2) conditions (19.9% and 14.0%, respectively). However, the quality of blastocysts, as evaluated by the total cell number, was better after IVM under 5% O(2) than under 20% O(2) (mean cell number, 43.5 and 37.8, respectively). When IVP embryos were cultured in IVC-PyrLac from Days 0 to 2 and subsequently in IVC-Glu from Days 2 to 6, the rate of blastocyst formation (25.3%) and cell number (48.7) were higher than the rates (5.8% to 18.1%) and numbers (35.4 to 37.1) with the IVC-Glu then IVC-Glu, the IVC-Glu then IVC-PyrLac, and the IVC-PyrLac then IVC-PyrLac regimens, respectively. We then prepared conditioned medium (CM) from culture of porcine oviductal epithelial cells for 2 days in IVC-PyrLac and evaluated its effect on development to the blastocyst stage. Cultivation in CM for the first 2 days, followed by IVC-Glu for a further 4 days, had a significantly greater effect in increasing the number of cells in the blastocyst (58.3) than did in IVC-PyrLac (48.4). Finally, we evaluated the ability of blastocysts, generated by IVM under 5% O(2) and IVC in CM, to develop to term. When Day 5 expanding blastocysts (mean cell number, 49.7) were transferred to an estrus-synchronized recipient (50 blastocysts per recipient), the recipient remained pregnant and farrowed eight normal piglets. Furthermore, when Day 6 expanded blastocysts (mean cell number, 80.2) were transferred to two estrus-synchronized recipients, both gilts remained pregnant and farrowed a total of 11 piglets. These results suggest that an excellent piglet production system can be established by using this modified IVP system, which produces high-quality porcine blastocysts. This system has advantages for the generation of cloned and transgenic pigs.

Animals↗

In-vitro fertilization and culture of mouse embryos in vitro significantly retards the onset of insulin-like growth factor-II expression from the zygotic genome.

In this study, the effect of in-vitro fertilization (IVF) and culture of mouse embryos in vitro on the normal expression of insulin-like growth factor-II (IFG-II) ligand and receptor was examined. The expression of IGF-II increased in a linear fashion at least up to the 8-cell stage of development. IGF-II expression in embryos collected fresh from the reproductive tract was significantly (P < 0.001) greater than in embryos fertilized in the reproductive tract and cultured in vitro (in-situ fertilized: ISF), and its expression was further reduced (P < 0.001) in IVF embryos at all development stages tested. The expression of IGF-II was significantly (P < 0.001) lower when embryos were cultured individually in 100 microl drops compared with culture in groups of 10 in 10 microl drops of medium. The addition of platelet activating factor to culture medium partially overcame this density-dependent decline of expression. Culture of ISF and IVF zygotes also caused the onset of new IGF-II mRNA transcription from the zygotic genome to be significantly (P < 0.001) retarded, until at least the 8-cell stage of development. This effect was greater (P < 0.05) for IVF than for ISF embryos. Neither IVF nor culture had any obvious effect on IFG-II/mannose-6-phosphate receptor (IGF-IIr) mRNA expression.

Animals↗