Potential use of embryo coculture with human in vitro fertilization procedures

Purpose This review was designed to outline potential uses of an embryo co-culture system in human assisted reproduction programs to improve embryo quality and pregnancy rates.Results The various cell types used in embryo co-culture were reviewed in addition to the use of co-culture for both animal and human embryos. Co-culture provides a method to enhance embryo development in an inadequate in vitro environment without compromising embryo quality. Human IVF laboratories have used various types of helper cells to improve rate of development, reduce cell fragmentation rate and in some instances increase pregnancy and implantation rates.Conclusion In conjuction with several assisted reproduction procedures such as IVF, microsurgical fertilization, cryopreservation and genetic evaluation, co-culture may increase the number of viable embryos for replacement and improve pregnancy rates.Presented at the First Asian Symposium on Micromanipulation and Co-culture, April 1, 1993, Singapore.     

Sex selection may be inadvertently performed in in-vitro fertilization--embryo transfer programmes

The present study aims to ascertain whether sex selection maybe inadvertently performed in human in-vitro fertilization (IVF)and embryo transfer (IVF-embryo transfer) programmes when selectingfor high quality embryos (those with the fastest cleaving ratesand/or the best morphology) at the fresh transfer cycle. Allpatients entering into the study were treated with gonadotrophinsafter pituitary suppression with gonadotrophin-releasing hormoneagonists (GnRHa) and had intrauterine embryo transfer on day2 post-insemination. These patients were retrospectively dividedinto three groups according to whether the difference in meannumber of cells between embryos transferred and all embryosavailable for transfer in a given cycle was less than (negativeselection), equal to (no selection) or greater (positive selection)than zero. In cycles resulting in singleton births, the sexratio of the resulting babies was significantly (P 0.005) shiftedtoward the female (88.8%) and to the male (90.0%) in the negativeand positive selection groups respectively. No shift in sexratio was observed in cycles resulting in multiple births. Maternalage was another independent factor affecting sex ratio at birth.Sex ratio was significantly (P 0.05) skewed in favour of males(62.7%) and females (71.4%) in women <35 and 235 years ofage respectively. Maternal age, number of embryos transferredand the event of selecting or not selecting the slowest cleavingembryos for transfer were entered automatically in a three-groupdiscriminant model for distinguishing cycles resulting in onlyboys, both boys and girls, and only girls. These data suggestthat (i) sex selection may be inadvertently performed in IVF-embryotransfer programmes when selecting for high quality embryosat the fresh transfer cycles; (ii) human endometria may be favourable,indifferent or hostile to either fast cleaving or slow cleavingembryos depending on maternal age; and (iii) ‘natural’sex selection may be performed for social, psychological ormedical reasons.     

Characterization and prediction of IVF cycles generating “slow-cleaving” embryos

Purpose To characterize and predict cycles generating slowcleaving embryos in in vitro fertilization, 86 cycles were retrospectively divided into two groups (slow, n=41, and fast, n=45 according to whether the number of blastomeres per embryo on day 3 was or > than the mean of the distribution, respectively.Results Cycles generating slowcleaving embryos were treated with luteinizing hormonereleasing hormone agonist before ovarian stimulation for a shorter period (12.1±0.5 versus 15.6±1.1 days; P0.01) and had higher immaturity grade of oocyte-corona-cumulus complexes which resulted in embryos (1.6±0.1 vs 1.3±0.1; P0.05) when compared to cycles producing fastcleaving embryos. Both variables entered in a logistic regression model applied in order to predict the probability of a cycle generating slowcleaving embryos (goodness-of-fit chisquare=180.0, degrees of freedom (df)=80, P=0.4786. This model predicted correctly 86.7% (13 of 15) of cycles generating slowcleaving embryos and 83.3% (10 of 12) of cycles producing fastcleaving embryos when the estimated probability of a cycle producing slowcleaving embryos was 0.7 or 0.3, respectively.Conclusion Shorter treatment with hormone-releasing hormone agonist before ovarian stimulation and higher immaturity grade of oocyte-corona-cumulus complexes which result in embryos are predictive characteristics of in vitro fertilization cycles generating slow-cleaving embryos.     

Oocyte quality and treatment outcome in intracytoplasmic sperm injection cycles of polycystic ovarian syndrome patients

Patients with polycystic ovarian syndrome (PCOS) have higher miscarriage rates. It is postulated that this is caused by a lower rate of mature oocytes, and a lower quality of embryos. Retrospectively we analysed 51 intracytoplasmic sperm injection (ICSI) cycles of 31 PCOS patients. These data were compared to age-matched controls (105 cycles) during the same period. All patients of both groups received gonadotrophin-releasing hormone (GnRH) agonists prior to gonadotrophin treatment. The rate of metaphase II oocytes (MII) was not different. However, the mean absolute number of normally fertilized oocytes was significantly higher in PCOS patients (5.00 versus 3.56, P < 0.01), due to a higher number of oocytes retrieved. More embryos were transferred by cycle in the PCOS group (2.69 versus 2.17, P < 0.05), with a higher cumulative embryo score. The overall and multiple pregnancy rate showed no differences and the clinical abortion rate was lower (21 versus 41.67%, P < 0.05) in the controls. Our findings demonstrate that negative factors unconnected to oocyte morphology must be present in PCOS patients. It is possible that only cytoplasmic, not nuclear, maturity is influenced in these patients.     

Extremes of body mass do not adversely affect the outcome of superovulation and in-vitro fertilization

The effect of extremes of body mass on ovulation is well recognized by clinicians. However, the effect of obesity and extreme underweight on the outcome of in-vitro fertilization (IVF) cycles has received relatively little attention. In a retrospective nested case-control study we examined the effect of the extremes of body mass index (BMI) on IVF-embryo transfer outcome at a university-based IVF unit. A total of 333 patients were included in the study; 76 obese patients (BMI > 27.9) with 152 controls, and 35 underweight patients (BMI < 19) with 70 controls. The patients were matched with their controls in age +/- 1 year, day 3 follicle stimulating hormone (FSH) concentration, daily dose of gonadotrophin (+/- 37.25 IU), gonadotrophin preparation and the year of treatment. The following parameters were compared between the study and control groups: duration of administration and dose of gonadotrophin, number of follicles aspirated, number of eggs, fertilization rate, number of embryos, serum oestradiol concentration on human chorionic gonadotrophin (HCG) day (peak oestradiol), clinical pregnancy rate, implantation rate, miscarriage rate, and incidence of ovarian hyperstimulation syndrome. Apart from a significantly lower peak oestradiol concentration (P = 0.009) in the obese patients, they and the underweight patients were not significantly different from their normal controls. The extremes of body mass index do not adversely affect the outcome of IVF-embryo transfer treatment. However, the obese patients had lower peak oestradiol concentrations than their normal controls despite receiving similar gonadotrophin doses.     

格列齐特致畸作用观察

目的观察国产格列齐特的致畸作用。②方法对受孕后第６天Ｗｉｓｔａｒ大鼠分别以８５,１７０,６８０ｍｇ／ｋｇ体质量的国产格列齐特（容积为５ｍＬ／ｋｇ体质量）灌胃给药,每天１次,连用１０ｄ;同步设立生理盐水组和敌枯双（５ｍｇ／ｋｇ体质量）对照组。于妊娠第２０天剖腹,取出胎鼠,观察并记录各组活胎数、死胎数以及活胎鼠生长发育等情况。③结果格列齐特各剂量组胚胎数损失率、活胎生长、发育等指标与生理盐水组相比,差异均无显著性（χ２＝０．３７５～３．０９８,Ｐ＞０．０５;Ｆ＝０．０３２～０．１７８,Ｐ＞０．０５）。④结论国产格列齐特无致畸作用     

LIF对体外培养小鼠孕早期胚胎发育及ICAM-1表达的影响

目的研究白血病抑制因子（ＬＩＦ）在胚胎发育中的作用并探讨其参与胚泡着床的机制。方法收集昆明种小鼠的单细胞受精卵,连续培养１２０ｈ,观察不同浓度ＬＩＦ对胚胎发育的影响;用免疫印迹法测定培养液中细胞间粘附分子（ＩＣＡＭ－１的表达水平。结果ＬＩＦ在０．１～１０ｎｇ／ｍｌ浓度之间对胚胎发育有促进作用,其作用在桑椹胚及胚泡期最明显（Ｐ＜０．０５）;ＬＩＦ增加胚胎ＩＣＡＭ－１的表达,其作用在０．１ｎｇ／ｍｌ浓度时最强,并随着浓度的增加而减弱。结论适应浓度的ＬＩＦ可促进胚胎发育,增加ＩＣＡＭ－１的表达,从而参与胚胎着床过程。     

叶酸拮抗乙酰水杨酸致大鼠卵黄囊毒性作用的研究

以全胚胎培养模型结合免疫组化和电镜技术等探讨了乙酰水杨酸和叶酸对大鼠卵黄囊及胚胎的影响。结果表明：培养基含乙酰水杨酸３００μｇ／ｍｌ组的卵黄囊直径和胚胎体长均显著低于阴性对照组,胚胎畸形率明显增高。组织学检查发现卵黄囊厚度变薄。间质层血岛、微血管数量明显减少,血管壁细胞不连续,血管发育不良。卵黄囊内皮层细胞顶端微绒毛少见。内皮层细胞的溶酶体、内质网及核蛋白体等结构和数量均有明显改变。而６０ｍｇ／ｋｇ叶酸灌胃鼠血清与乙酰水杨酸联合应用后,则卵黄囊的上述毒性作用明显减轻或消失,提示叶酸能明显拮抗乙酰水杨酸致大鼠卵黄囊的毒性作用。     

共培养在小鼠胚胎发育过程中的作用

目的 通过人子宫内膜上皮与小鼠胚胎共培养,了解其对胚胎发育的影响。方法 观察共培养２４、３６ｈ及６０ｈ后的小鼠胚胎,并分级,结果 １共培养组停留于２细胞胚胎数显著少于对照组;２共培育２４、３６ｈ后,鼠胚１￣３有胚胎比例较对照组增加,差异有显著性;６０ｈ后,１￣３级胚胎比较与对照组相比差异无显著性。结论 人子宫内膜上皮与小鼠胚胎短期共培养有利于改善胚胎质量。     

Chick gonadogenesis following early surgical bursectomy

Left ovaries of bursectomized chick embryos were examined on the 17th day of incubation in comparison to normal and sham-operated controls, by histological and histochemical observations. The results show that in bursectomized embryos the cortex appears irregulary developed, with a significant decrease in the mean thickness and in the percentage of the secondary sex cords in the total cortical area. Furthermore, the germinal epithelium appears thicker and the subcortical medulla and the tunica albuginea more compact. The greater activity of the enzyme ⁵–3-hydroxysteroid dehydrogenase ( ⁵3HSD) found in ovaries of bursectomized embryos (histochemical method) could be related to an endocrine dismetabolism affecting the cortical development. On the basis of these results and those of other authors, some hypotheses are advanced. In particular, an action of the bursal factor on GTH receptors could be the factor responsible of the enhanced steroidogenic activity altering the hormonal environment.