Search PubMed⌕ Search

Biomedical subjects

A Bongso

Publications and source records attributed to A Bongso.

At least 55 records · Page 3Linked to original sources
PubMed1992

Improved pregnancy rate after transfer of embryos grown in human fallopian tubal cell coculture.

OBJECTIVE: To evaluate the embryonic behavior in vitro and the pregnancy and implantation rates of embryos grown in a human ampullary cell coculture system. DESIGN: In a prospective study, two pronuclei embryos were cultured on human ampullary feeder layers up to the two to six-cell and blastocyst stages and replaced either as tubal, uterine, or sequential transfers. SETTING: Assisted reproductive technology program in a university-based hospital. PATIENTS: Fifty women with a mean age of 35.6 years who went through a single coculture cycle. Thirty of the patients were admitted for in vitro fertilization (IVF) and 20 for tubal embryo transfer (TET). RESULTS: The overall clinical pregnancy rate (PR) for all 50 patients was 44% per cycle (IVF, 37%; TET, 55%) and the implantation rate was 31.8% (IVF, 31.0%; TET, 32.6%). Sixty-eight percent of pregnant patients were over 35 years, and 68% had two previously failed assisted reproduction cycles. Five of 9 patients who received sequential transfers became pregnant. Three of the 22 pregnancies aborted (2 after sequential transfer), and there was one ectopic. Overall, 88% of two to six-cell stage embryos were of good quality. CONCLUSIONS: The human ampullary coculture system produces better quality embryos, increased numbers of blastocysts with improved PRs and implantation rates. The beneficial effects of the feeder layer may be through the release of embryotrophic factors and detoxification of the medium by the cells. Coculture is a new concept in assisted reproduction and has tremendous potential in boosting conception rates by mimicking the in vivo environment.

Adult↗
PubMed1992

The evaluation of various culture media in combination with dimethylsulfoxide for ultrarapid freezing of murine embryos.

Bicarbonate-buffered HTF medium, Medicult, and T6 are as effective as PB1 medium when used in combination with DMSO in ultrarapid freezing of two-cell mouse embryos. However, the use of phosphate-buffered T6 results in reduced in vitro development and inner cell mass size as compared with bicarbonate- and Hepes-buffered T6 when used with 3.5 M of DMSO. Hence, the use of this media for ultrarapid freezing should be avoided when this concentration of DMSO is used.

Animals↗
PubMed1992

Outcome of 143 pregnancies conceived by assisted reproductive techniques.

One hundred and forty-three pregnancies conceived by assisted reproductive techniques (ART) from October 1985 to June 1989 in the National University Hospital, Singapore, resulted in 66 deliveries and 89 babies. There were 27 (18.7%) biochemical pregnancies, 44 (30.7%) clinical miscarriages and 6 (4.2%) ectopic pregnancies when total pregnancies were considered. Of those who continued pregnancy to second trimester multiple births occurred in 20 (13.3%) patients. A high incidence of vaginal bleeding and hypertension in pregnancy was noted in 32 (48.5%) patients and 18 (27.3%) patients, respectively. Caesarean section was the method of delivery in 48.5% of patients. Twenty-six (29.2%) babies required admission to the neonatal intensive care unit. All babies except one set of twins delivered at 24 weeks of amenorrhoea survived. Fetal abnormality was noted in 2 cases.

Adult↗
PubMed1992

Amniocentesis and its complications.

This study was conducted in order to evaluate whether the performance of an experienced operator had any significant influence in reducing the incidence of complications in amniocentesis; 1,459 women had amniocentesis performed under ultrasound guidance; 1,324 were performed by experienced operators and 135 cases by less experienced operators. Complications like fetal loss, blood-stained amniotic fluid, culture failure, multiple needle puncture, leaking liquor, fetal trauma and error in results were compared in the 2 groups. This study demonstrated that amniocentesis performed by an experienced operator decreased the various complications associated with amniocentesis.

Amniocentesis↗
PubMed1992

The first oocyte donation pregnancy home-bred and delivered in Singapore to illustrate a simplified oocyte donation programme--no more embryo freezing, synchronisation or disruption of social life.

The wait for an oocyte donor is highly unpredictable and stressful. The recipients may have to remain contactable at all times. Even when a donor is present, their reproductive cycles may not be in synchrony to enable gamete or embryo replacement, and embryo freezing is required for the transfer of embryos in the subsequent cycle. After the release of the Guidelines for Assisted Reproductive Technique by the Ministry of Health we have established a simplified oocyte donation programme with which the need for synchronisation, embryo freezing and the disruption to the recipient couple's social life are eliminated. To illustrate, we report the first report of oocyte donation pregnancy home bred and delivered in Singapore.

Adult↗
PubMed1991

Centrioles in the beginning of human development.

We demonstrate the presence of centrioles in fertilized human oocytes at syngamy. Single or double centrioles within centrosomes were detected by transmission electron microscopy at one pole of the first cleavage spindle in normal and dispermic embryos (25-26 hr after insemination). Sperm centrioles were also closely associated with the male pronucleus (16-20 hr after insemination) in pronuclear stage embryos. A tripolar spindle derived from a tripronuclear embryo is also demonstrated with two centrioles at one pole. The data provide evidence that human centrioles, as those in most other animals, and unlike the mouse, are paternally derived, thus supporting Boveri's classical theory. Furthermore, this study provides insights to the proposed mechanisms of aberrant cleavage patterns of dispermic human embryos.

Blastocyst↗
PubMed1991

Improved fertilization rates of human oocytes in coculture.

Passaged human tubal ampullary epithelial cells from cell lines were used to evaluate fertilization rates and the support of early human embryonic cleavage in vitro. A total of 225 mature oocytes from 32 patients was used in this study. Oocytes from each patient were equally allotted at random to two groups. One hundred thirty-two oocytes were inseminated in the presence of passaged human ampullary cells, while 123 oocytes were inseminated in culture medium alone. Fertilized oocytes were transferred to tubal ampullary cell monolayers and monitored for up to 48 hr. Eighty-five percent of oocytes fertilized in coculture, as compared to 67% in medium alone (P less than 0.01). A higher percentage of good-quality embryos was observed in cocultures than in controls (79 vs 67%; P less than 0.05). Binding of sperm to ampullary monolayer cells was observed. Human ampullary-cell cocultures may be useful to improve fertilization rates and embryonic viability and thus increase take-home baby rates for in vitro fertilization programs.

Adult↗
PubMed1991

Preimplantation genetics: chromosomes of fragmented human embryos.

STUDY OBJECTIVE: To examine the chromosome makeup of fragmented human embryos. DESIGN: Prospective. SETTING: Assisted reproductive technology (ART) program. PATIENTS: One hundred twenty-one poor-quality embryos from 58 patients 31 to 40 years of age admitted for an ART program were examined for chromosome makeup. RESULTS: Chromosome anomalies were observed in 31.9% (29/91) of poor-quality embryos, 19.8% (18/91) displayed mosaicism (diploid/haploid, diploid/triploid, diploid/aneuploid), 5.5% (5/91) showed polyploidy, 2.2% (2/91) had pulverized chromosomes, 2.2% (2/91) revealed aneuploidy, 1.1% (1/91) had prematurely condensed chromosomes, and 1.1% (1/91) had structural rearrangements involving chromosome number 2. The mean age of patients showing anomalies (36.5 years) was not significantly higher than the mean for the entire group (35.5 years). CONCLUSIONS: The incidence of chromosome anomalies in fragmented human embryos is high. These anomalies originate either in the gametes or through mitotic nondisjunction within the embryos. It is not advisable to replace such embryos into patients going through in vitro fertilization.

Adult↗
PubMed1991

Cocultures: a new lead in embryo quality improvement for assisted reproduction.

One of the contributory causes to poor PRs in assisted reproduction has been the decreased viability of transferred embryos and the transfer of four-cell embryos into an environment that naturally would be receptive only to 5-day-old blastocysts. In this paper, we have reviewed our own work and that of others on the role of tubal ampullary cells (cocultures) to mimic the in vivo environment to bring about improved embryo quality and an increased number of blastocysts for replacement in IVF patients. The establishment, maintenance, and behavior of human tubal cell lines is first presented, followed by their use as cocultures for fertilization and cleavage of embryos. The mode of action, specificity, and cryopreservation of ampullary cells are also discussed. The currently available results of pregnancies after cocultures are presented together with future aspects of research that are necessary to refine the coculture system. The ultimate aim is to mimic in vivo conditions in vitro, so that at least the PRs of assisted conception can be parallel to normal fecundity in the human. Therefore, a very attractive future includes the freezing of blastocysts generated from coculture, thawing, and replacing them in natural cycles.

Animals↗
PubMed1991

Microinjection of human oocytes: a technique for severe oligoasthenoteratozoospermia.

OBJECTIVE: To determine outcome after microinjection with very poor quality sperm and after failed fertilization. DESIGN: Group 1, fresh oocytes from patients with very low sperm density and motility on the day of oocyte recovery; Group 2, 1-day-old oocytes that failed to fertilize. SETTING: All material was obtained from the National University Hospital. PATIENTS: One hundred and thirty-one from group 1; 35 from group 2. INTERVENTIONS: Sperm was injected subzonally or directly into the ooplasm. MAIN OUTCOME MEASURE: Normal and abnormal fertilization and pregnancy. RESULTS: Subzonal transfer was done on 771 oocytes in group 1 and 188 oocytes in group 2. Multiple sperm were transferred [mean of 6.6 for group 1 and 7.3 for group 2]. Monospermic fertilization occurred in 16.6% and 14.9%, respectively. Polyspermy and parthenogenetic activation were low at 2.3% and 2.8%, respectively. Five pregnancies were obtained, but only one delivered. Ooplasmic injection (single sperm heads) was done in 38 oocytes from three patients with extremely severe oligozoospermia; only four two-pronuclear zygotes were obtained and replaced into two patients, without any resulting pregnancy. CONCLUSIONS: Subzonal transfer may be a viable technique for patients with severe sperm problems.

Female↗
PubMed1991

Cocultures in human assisted reproduction. Support of embryos in vitro and their specificity.

Assisted reproductive techniques (ART) have contributed tremendously to alleviating infertility in childless couples. However, the "take-home baby" rate for in vitro fertilization (IVF) has been much below the rate for normal fertile couples and for the other tubal procedures such as gamete intrafallopian transfer (GIFT) and tubal embryo transfer (TET). It was therefore speculated that the tubal environment might be playing an important role towards the viability of the embryo and that, in IVF, 4-6 cell stage embryos that were usually replaced directly into the uterus might not be receiving the beneficial effects of the tubal environment. Pronuclear stage human and mouse embryos were thus cocultured with reproductive and other somatic cell types to evaluate the quality of the various cleaving stages and the percentage yield of blastocysts. Human ampullary cell cultures were established in 6 to 7 days and kept alive through one menstrual cycle. Cleavage to the compacted and cavitating stages was achieved in 78% and 69%, respectively, of human embryos cocultured in 24-48 hour human ampullary subcultures as compared to 50% and 33%, respectively, for embryos grown in culture medium alone. The percentages of expanded blastocysts and hatching stages in such cocultures were not significantly different from those of controls. However, human ampullary and cumulus and mouse ampullary and muscle fibroblast cultures supported cleavage and development of mouse embryos up to the hatching stages as well as or better than controls. It thus appears that there is no absolute specificity for a reproductive tract source of cocultured cells and that the beneficial effects of ampullary and cumulus cells are not species-specific. The coculture system also appears to overcome the embryonic blocks of the human and mouse, which may be mediated via growth factors that activate the embryonic genome.

Animals↗
PubMed1990

Ultrastructure of preimplantation human embryos co-cultured with human ampullary cells.

Ova with two pronuclei were co-cultured with established human ampullary cell lines and various stages of preimplantation embryonic development were monitored by Nomarski optics and then assessed by transmission electron microscopy (TEM). Fifteen embryos ranging from the 2-cell stage to blastocyst hatching were examined for normal and abnormal features. Their ultrastructure was similar to that of embryos cultured in Whittingham's T6 medium, reported previously. Seven embryos were evidently morphologically normal and showed good organization of fine structure. Most cellular organelles underwent progressive changes during early development. There was evidence of enhanced embryonic genome activation at the 8-cell stage. Invariably, all embryos had few too many fragments, some internalized, which were later segregated into the blastocoele or found outside the trophoblast of the late morula and blastocysts. Six grossly 'normal' embryos assessed by Nomarski had multiple nuclei of various dimensions, which highlights the subjectivity of embryo assessment in the IVF laboratory. Incomplete incorporation of chromatin into nuclei and formation of micronuclei were evident in some blastomeres. The results are discussed in relation to early embryonic loss, prevalent in IVF. Significant events reported include the detection of centrioles at the 8-cell stage, cavitation of the early blastocyst and the initiation of blastocyst hatching visualized by TEM.

Blastocyst↗
PubMed1990

Co-cultures: their relevance to assisted reproduction.

Assisted reproductive techniques have contributed significantly to alleviating subfertility in the childless couple. However, the take-home baby rates have been very low throughout the world. One of the contributory causes has been the reduced viability of replaced embryos brought about by suboptimal in vitro conditions. The culture of human embryos in the presence of passaged human tubal ampullary monolayers (co-cultures) is an attractive approach to improving the viability of embryos for assisted reproduction. Seventy per cent of blastocysts can be produced in human ampullary co-culture as compared to 33% in standard culture media. This paper discusses the various roles of human co-cultures in assisted reproduction and provides an opinion as to how the transfer of blastocysts produced via the co-culture system could enhance pregnancy rates. Particular emphasis is placed on human oviductal characteristics, the various co-culture systems, screening of co-cultures for microbes, freezing of ampullary cells, growth factors and embryonic blocks, specificity of co-cultures, sperm hyperactivation in co-culture and pregnancy rates. The first patient on a clinical trial who had four of her oocytes fertilized and grown in human ampullary co-culture and then replaced into her uterus became pregnant. The co-culture system may have tremendous potential in supporting human embryonic growth via embryotrophic factors.

Animals↗
PubMed1989

Improved sperm concentration, motility, and fertilization rates following Ficoll treatment of sperm in a human in vitro fertilization program.

Duplicate sperm samples from the spouses of 54 patients admitted to an in vitro fertilization program were prepared by the swim-up and a simplified procedure using Ficoll. Cellsoft (CRYO Resources, New York, NY) sperm curvilinear velocities (microns/sec) and mean amplitude of lateral head displacement values (microns) equivalent to grade 1 and 2 visual sperm motility were significantly higher for Ficoll as compared with swim-up samples (P less than 0.01). Fertilization rates were significantly higher in the Ficoll as compared with the swim-up group for poor semen samples (grade less than 2: 58% versus 24%; P less than 0.01) and normal semen samples (grade greater than or equal to 2: 85% versus 78%; P less than 0.05). Ficoll sperm separation appears to be an excellent method of yielding increased fertilization rates in in vitro fertilization programs.

Female↗
PubMed1989

Transfer of human sperm into the perivitelline space of human oocytes after zona-drilling or zona-puncture.

To evaluate the transfer of sperm from severely oligozoospermic men into the perivitelline space of mature oocytes, zona-drilling with acid phosphate-buffered saline (PBS) and direct zona-puncture in the presence of cytochalasin D were studied. Zona-drilling also was done for eggs from patients with previous failed in vitro fertilization (IVF). Forty-seven eggs from seven patients with oligozoospermia and three patients with failed IVF had a mean of between 2.6 and 3.6 sperm transferred into the perivitelline space. In the group whose eggs had zona-drilling with acid PBS, 1 of 13 eggs fertilized from the oligozoospermic category, while there was no fertilization from the failed IVF category. Karyotyping of the unfertilized eggs after zona-drilling revealed a high incidence (2/5 and 3/7, respectively) of possible arrest at anaphase II after reinitiation of meiosis. In the group whose eggs were directly punctured through the zona in the presence of cytochalasin D, there was no fertilization in 23 undamaged eggs. Two of the 15 interpretable karyotypes were aneuploid, but this incidence is within that observed for our unfertilized eggs after IVF. Hence, the use of acid PBS for zona-drilling is not advised. Moreover, transfer of sperm from men with previous failed fertilization resulted in poor fertilization rates.

Cytochalasin D↗
PubMed1989

Establishment of human ampullary cell cultures.

Epithelial cells from the ampulla of healthy oviducts from 16 women aged 33-41 years and at different phases of their menstrual cycles were used to establish primary cultures and the continuation of a cell line. The morphology and behaviour of these cells in vitro were evaluated using Nomarski's inverted optics, scanning and transmission electron microscopy. Cells from all patients produced confluent monolayers in 6-7 days with no significant relationship of cell growth with stage of cycle. Fourteen primary cultures were of the epithelioid type while two showed mixed epithelioid and fibroblast-like growth. Two distinct cell types (ciliated and secretory) were observed in primary culture. Secretory cells showed several microvilli of different lengths and distribution. Secretory cells predominated over ciliated cells in all patients, but maximum ciliation occurred around the time of ovulation. Structural features of the cells in vitro were remarkably similar to those described in vivo. Ampullary cells could be maintained in vitro through four to six passages with 3-4 days of growth between passages. Sub-cultured cells were all secretory and were of two types (I and II) based on ultrastructure. Secretory vesicles containing electron-dense material and lipids were observed in these cells. The method described allows for the use of ampullary cells as feeder layers for IVF and support of cleaving human embryos and the evaluation of the biochemical events surrounding fertilization and ectopic pregnancies.

Adult↗