Nuclear morphology,diameter and meiotic competence of buffalo oocytes relative to follicle size

The nuclear morphology, diameter and in vitro meiotic competence of buffalo oocytes was compared relative to follicle size. Cumulus-oocyte complexes (COCs) were collected from 1-<2, 2-<3, 3-<4, 4-<6 and 6-<8 mm follicles from abattoir ovaries. Cumulus cells were removed using 3 mg mL(-1) hyaluronidase in saline and repeated pipetting. Denuded oocytes were measured, fixed in 3% glutaraldehyde, stained with 4,6-diamidoino-2-phenylindole and evaluated for nuclear morphology, namely the stage of germinal vesicle (GV) development before in vitro maturation (IVM). The COCs from >2-mm follicles were matured in vitro in their respective size groups for 24 h in Medium 199 supplemented with 10 microg mL(-1) follicle-stimulating hormone, 10 microg mL(-1) luteinizing hormone, 1.5 microg mL(-1) oestradiol, 75 microg mL(-1) streptomycin, 100 IU mL(-1) penicillin, 10 mM HEPES and 10% fetal bovine serum. Matured oocytes were fixed, stained and evaluated for GV status and meiotic development. The number of oocytes collected from follicles 1-<8 mm in diameter averaged 1.82 per ovary. Oocytes from follicles 1-<2 mm (107.7 +/- 1.6 microm), 2-<3 mm (108 +/- 1.1 microm) and 3-<4 mm (114.6 +/- 1.3 microm) in diameter were smaller in diameter (P < 0.05) than oocytes from follicles 4-<6 mm (124.4 +/- 1.3 microm) and 6-<8 mm (131.9 +/- 1.4 microm) in diameter. A majority of oocytes (P< 0.05) from <4-mm follicles was at the initial stages of GV development (GV-I, II and III), whereas oocytes from 4-<6- and 6-<8-mm follicles were at the final stages of GV-IV (35.0 and 21.6% respectively) and GV-V (49.1 and 67.5% respectively). Poor IVM rates of 32.0% and 32.7% to metaphase (M)-II were observed for oocytes isolated from 2-<3- and 3-<4-mm follicles, respectively, whereas significantly (P< 0.05) more oocytes from 4-<6- and 6-<8-mm follicles reached M-II (67.1% and 79.1% respectively). In conclusion, buffalo oocytes displayed a size-dependent ability to undergo meiotic maturation and we suggest that oocytes from >4-mm follicles should be considered in buffalo in vitro fertilization systems for better results.     

Relationship between follicle size and oocyte developmental competence in prepubertal and adult pigs

The present study compared the distribution and steroid composition of 3-, 4- and 5-8-mm follicles on the surface of prepubertal and adult ovaries, and determined the relationship between follicle size and developmental competence of oocytes following parthenogenetic activation. The effect of 1 mm dibutyryl cAMP (dbcAMP) for the first 22 h of in vitro maturation (IVM) on the embryo development of prepubertal oocytes from the three follicle size cohorts was also determined. Compared with adult, prepubertal ovaries contained a higher proportion of 3-mm follicles (46 v. 72%, respectively), but a lower proportion of 4-mm (33 v. 22%, respectively) and 5-8-mm follicles (21 v. 6%, respectively). Adult follicular fluid (FF) contained 11-fold higher levels of progesterone (P4) than prepubertal FF, with similar levels observed between all adult follicle sizes. In prepubertal FF, the P4 concentration increased with follicle size from 3 to 4 to 5-8 mm. Rates of blastocyst development following parthenogenetic activation of adult oocytes from all three follicles sizes were similar (approximately 55%), whereas rates from prepubertal oocytes increased with increasing follicle size from 3 (17%) to 4 (36%) to 5-8 mm (55%). Treatment with dbcAMP for the first 22 h of IVM led to a 1.5-fold increase in the rate of blastocyst development for prepubertal oocytes from 3-mm follicles, but had no effect on prepubertal oocytes from the 4 and 5-8 mm classes. Mean blastocyst cell number increased with follicle size in prepubertal ovaries and was similar for all follicle sizes in adult ovaries. The present study demonstrates that the low efficiency of in vitro embryo production observed using prepubertal compared with adult pig oocytes is due to a greater proportion of 3-mm follicles on prepubertal ovaries, which contain oocytes of inferior developmental competence.     

Dose-dependent effects of gonadotropin on oocyte developmental competence and apoptosis

The aim of the present study was to evaluate the effect of gonadotropins (Gn) on oocyte maturation, developmental competence and apoptosis in an animal model. Bovine cumulus-oocyte complexes (COCs) were matured for 24 h in media supplemented with varying concentrations of Bravelle (B), B + Menopur (B+M) or B + Repronex (B + R) (Ferring Pharmaceuticals, Parsiappany, NJ, USA). Then, nuclear maturation, embryo development, and apoptosis in cumulus cells and oocytes were evaluated. Low to moderate Gn concentrations (75-75 00 mIUmL(-1)) effectively improved nuclear maturation and in vitro development. Higher concentrations of Gn (75 000 mIUmL(-1)) did not have any added beneficial effects and nuclear maturation and blastocyst rates in the presence of these concentrations were comparable to control (P>0.05). Most COCs showed slight apoptosis when exposed to 75, 750 and 75 00 mIUmL(-1) Gn; however, when the concentration was increased to 75 000 mIUmL(-1), the proportion of moderately apoptotic COCs increased. In conclusion, extremely high concentrations of Gn have detrimental effects on oocyte nuclear maturation and embryo development and increase apoptosis in cumulus cells, suggesting the importance of judicious use of Gn in assisted reproductive technologies (ART).     

Effect of type of cryoprotectant on morphology and developmental competence of in vitro-matured buffalo (Bubalus bubalis) oocytes subjected to slow freezing or vitrification

The present study examined the effects of different cryoprotectants on morphology and developmental competence of in vitro-matured buffalo oocytes after slow freezing or vitrification. After slow freezing in dimethyl sulfoxide (DMSO), ethylene glycol (EG) or 1,2-propanediol (PROH), at 1.0 or 1.5 m each, the proportion of morphologically normal oocytes recovered was significantly higher (P < 0.05) with 1.5 than 1.0 m for all cryoprotectants and was highest (P < 0.05) for 1.5 m DMSO. Following vitrification, the percentage of morphologically normal oocytes recovered was lower (P < 0.01) for 40% EG than for 40% DMSO, 20% EG + 20% DMSO or 20% EG + 20% PROH. The most common damage, irrespective of the cryopreservation method, was loss of cumulus mass. The cleavage rate and the proportion of vitrified-warmed oocytes that developed to morulae/blastocysts were significantly higher (P < 0.01) for 20% EG + 20% DMSO than for the other groups. A higher proportion of oocytes developed to morulae (11.5% v. 4.3%) or blastocysts (5.4% v. 0.6%) after vitrification in 20% EG + 20% DMSO than after slow freezing in 1.5 m DMSO. In conclusion, vitrification was more effective than slow freezing for the cryopreservation of in vitro-matured buffalo oocytes.     

Effects of milrinone and butyrolactone-I on porcine oocyte meiotic progression and developmental competence

Inappropriate coordination of oocyte nuclear and cytoplasmic maturation is thought to contribute to the poor efficiency of embryo production in vitro. With the aim of improving this coordination, the effects of milrinone, an inhibitor of type 3 phosphodiesterases, and butyrolactone-I, a selective inhibitor of cdc2 kinases, on porcine oocyte maturation were investigated. Oocytes recovered from slaughterhouse-derived ovaries of prepubertal animals were treated with the inhibitors for 24 h. At concentrations of 50 and 250 microm, milrinone reversibly inhibited meiotic progression in 57% and 71% of oocytes, respectively. The presence or absence of milrinone in the medium used to wash oocytes for 30 min did not alter the inhibitory effect of the 24 h treatment. At concentrations of 25 and 50 microm, butyrolactone-I inhibited meiotic progression in 61% and 66% of oocytes, respectively, but the effect was not fully reversible in the absence of follicle-stimulating hormone (FSH). The presence of FSH during the butyrolactone-I treatment period increased the ability of oocytes to subsequently complete meiosis at 44 h without changing the inhibitory effect at 24 h. Following in vitro fertilisation at 44 and 50 h, treatment with butyrolactone-I and milrinone, alone or in combination, did not alter embryo cleavage rate, blastocyst formation rate or blastocyst cell number. Despite the different actions of milrinone and butyrolactone-I, the present study demonstrates that these reagents inhibit meiotic progression to a similar extent in the presence of FSH while maintaining developmental competence in porcine oocytes.     

Effects of lamb age, hormone stimulation and response to hormone stimulation on the yield and in vitro developmental competence of prepubertal lamb oocytes

Experiments were conducted to determine the effects of lamb age, hormone stimulation (Experiment 1) and response to stimulation (Experiment 2) on the in vitro production of embryos from prepubertal lambs aged 3-4 and 6-7 weeks of age. For 3-4-week-old lambs, hormone stimulation increased the number of follicles (29.9 +/- 15.3 v. 70.6 +/- 8.2), oocytes per ovary (18.3 +/- 6.3 v. 39.3 +/- 5.8) and oocyte development to the blastocyst stage (0/192 (0.0%) v. 115/661 (17.4%); P < 0.05). Lamb age (3-4 v. 6-7 weeks old) increased oocyte development to the blastocyst stage (115/661 (17.4%) v. 120/562 (21.4%) respectively). In Experiment 2, hormone-stimulated lambs (3-4 and 6-7 weeks old) were divided into low, medium or high responders based on the number of ovarian follicles (<20, 20-50 and >100 follicles per ovary respectively). The response to hormone stimulation did not affect oocyte recovery rate, but the number of oocytes suitable for culture was increased for high-responding 3-4-week-old lambs only (P < 0.05). Oocyte development to the blastocyst stage was not affected by response to stimulation for 3-4-week-old lambs (15.2-25.6%; P > 0.05), but was reduced for high (6.7%) compared with low (19.5%) and medium (30.9%) responding 6-7-week-old lambs (P < 0.05). These results demonstrate that the production of embryos from prepubertal lambs is increased by hormone stimulation and lamb age and the response to stimulation does not affect embryo production from 3-4-week-old lambs, although by 6-7 weeks of age a high response to stimulation reduces blastocyst formation.     

Temporal effects of exogenous oocyte-secreted factors on bovine oocyte developmental competence during IVM

We investigated whether paracrine signalling between the bovine oocyte and cumulus cells is altered during the course of in vitro maturation (IVM). Bovine COCs were cocultured with denuded oocytes or treated with specific oocyte-secreted factors, namely recombinant bone morphogenetic protein (BMP)-15 or growth differentiation factor (GDF)-9, beginning from 0 or 9h IVM. To generate a 9-h denuded oocyte (DO) group, COCs were cultured intact for the first 9h of IVM and then denuded. Coculturing intact COCs with DOs denuded immediately after collection or following 9h of maturation did not affect cleavage rate, but improved blastocyst yield (P<0.05) on Day 8 (51 and 61%, respectively; P<0.05) and cell number compared with COCs cultured alone (41%). Significantly, we observed higher levels of endogenous GDF-9 and BMP-15 protein in oocytes of COCs matured for 9h compared with no incubation. The addition of 175 ng mL(-1) GDF-9 or 10%v/v BMP-15 from partially purified transfected 293H cell supernatant for 24h IVM significantly enhanced development to the blastocyst stage from 40% (control) to 51 and 47%, respectively (P<0.05). However, treatment of COCs with GDF-9 or BMP-15 between 9 and 24h of IVM did not increase blastocyst yield. These results provide evidence of quantitative and possibly qualitative temporal changes in oocyte paracrine factor production during IVM.     

BDNF对小鼠卵母细胞体外成熟及发育能力的影响

目的:观察脑源性神经营养因子(BDNF)对小鼠未成熟卵的体外成熟及发育能力的影响。方法:以α-MEM为基础培养液,添加不同浓度(0、1、5、10 ng/ml)的BDNF以及FSH、FBS培养小鼠未成熟卵,并进行体外受精,观察卵母细胞成熟率、受精率和胚胎发育至囊胚的能力,了解不同培养条件下BDNF对卵母细胞发育能力的影响。结果:当体外成熟培养液中含有FSH和10%的FBS时,与体外成熟对照组比较,BDNF虽然不影响卵母细胞的成熟率和受精率,但BDNF 5 ng/ml组的囊胚形成率(75.00%)显著高于体外成熟对照组(56.63%),而接近体内成熟组(76.92%);当培养液中仅含FBS时,各组间卵母细胞成熟率和受精率没有差异,但与对照组比较,BDNF显著提高囊胚形成率;当培养液中不含FBS、FSH时,虽然无囊胚形成,但BDNF显著提高了卵母细胞的受精率。结论:BDNF能促进小鼠未成熟卵胞质的发育,提高卵母细胞的发育能力。     

Relationship between donor animal age,follicular fluid steroid content and oocyte developmental competence in the pig

The developmental competence of oocytes recovered from the ovaries of slaughtered prepubertal and adult pigs was evaluated after in vitro maturation, parthenogenetic activation and culture in vitro. In addition, the effect of prepubertal and adult follicular fluid (FF) on the developmental competence of prepubertal and adult oocytes was investigated. When matured in adult FF, the rates of cleavage (92 v. 73% P < 0.01) and blastocyst formation (57 v. 38%; P < 0.05) were greater for adult oocytes than for prepubertal oocytes. Blastocysts derived from adult oocytes had more trophectoderm cells (43 v. 30; P < 0.05) and total cells (51 v. 36; P < 0.05) than blastocysts derived from prepubertal oocytes. The developmental competence of prepubertal oocytes was not affected by the FF donor age, whereas the developmental competence of adult oocytes was. Blastocysts derived from adult oocytes matured in adult FF had more trophectoderm cells (38 v. 24; P < 0.005), inner cell mass cells (7 v. 3; P < 0.01) and total cells (45 v. 27; P < 0.001) than blastocysts derived from adult oocytes matured in prepubertal FF. Characterization of the steroid content of the FF used to supplement the maturation medium revealed that adult FF contained more progesterone (42 v. 23 ng mL(-1); P < 0.005) and androstenedione (70 v. 16 ng mL(-1); P < 0.05) than prepubertal FF. In addition, the molar ratios of progesterone to androstenedione, androstenedione to 17beta-oestradiol and androstenedione to testosterone differed (P < 0.05) between prepubertal and adult FF. The results support the hypothesis that a greater proportion of adult oocytes than of prepubertal oocytes has completed 'oocyte capacitation'. The differences in FF steroid content are indicative of the different follicular environments from which the prepubertal and adult oocytes were isolated, and may be attributed to the observed effects on oocyte developmental competence.     

Effect of commercially available PMSG on maturation, fertilization and embryo development of buffalo oocytes in vitro

In vitro fertilization (IVF) technology provides an opportunity to produce embryos for genetic manipulation, embryo transfer and basic research in developmental physiology, and can be exploited for emerging biotechnologies such as transgenesis and cloning. In the present study, the effects of different concentrations of commercially available pregnant mare serum gonadotrophin (PMSG) (Folligon; Intervet, International B.V, Boxmeer, Holland) in oocyte culture media, on maturation, fertilization and embryonic development of buffalo oocytes in vitro were investigated. Oocytes aspirated from abattoir-derived ovaries were cultured in media containing TCM-199 + PMSG at 0, 2.5, 20, 30, 40 and 50 IU mL(-1) in presence or absence of steer serum (10%) for 24 h in a CO2 incubator. The maturation rate was assessed on the basis of degree of expansion of cumulus cells. The matured oocytes were inseminated with 9-10 x 10(6) spermatozoa mL(-1) in Brackett and Oliphant medium and the cleavage rate was recorded 40-42 h after insemination. Uncleaved oocytes were stained with aceto-orcein for evaluation of fertilization rates. The cleaved embryos were further cultured in TCM-199 + 10% steer serum on buffalo oviducal cell monolayer for 7 days. Maturation, fertilization, cleavage and embryonic development were significantly higher (P < 0.05) in oocytes cultured in TCM-199 + 10% steer serum supplemented with 40 and 50 IU PMSG mL(-1). It is concluded that commercially available PMSG can effectively be used in place of pure follicle-stimulating hormone for in vitro maturation of buffalo oocytes, making it cost effective for IVF studies.     

体外培养成熟技术对未成熟卵母细胞冻融的影响

目的:探索影响未成熟卵母细胞冻融技术的关键因素。方法:A组:来源于体外受精-胚胎移植(IVF-ET)周期中自愿捐献的多余的成熟卵母细胞(MⅡ期),共56个;B组:来源于手术切除的卵巢组织中的未成熟卵母细胞(GV或MⅠ),共67个。不同成熟时期卵母细胞经慢冻快融后培养和体外受精,观察其体外成熟、受精及胚胎发育情况。结果:A组与B组相比,两组冻融后的存活率有显著性差异(60.71%vs 77.61%,P<0.05);A组受精率高于B组,但两组比较无显著性差异(61.76%vs 50.00%,P>0.05);A组与B组相比,两组冻融后的卵裂率和优质胚胎率有显著性差异(76.19%vs 37.50%,47.62%vs 12.50%,P<0.05)。A组获2枚囊胚,而B组没有囊胚培养成功。结论:体外成熟培养技术可能是影响冻融后未成熟卵母细胞发育的关键因素。     

砷对小鼠卵母细胞成熟和体外受精的影响

目的　探讨三氧化二砷（Ａｓ２Ｏ３） 对小鼠生殖作用的影响。方法　采用小鼠卵母细胞体外培养、体外受精的方法研究Ａｓ２Ｏ３ 对卵母细胞成熟和体外受精的影响。结果　Ａｓ２Ｏ３ 对小鼠卵母细胞生发泡破裂、超排卵的卵母细胞数目没有影响, 但可以抑制卵母细胞第一极体的释放, 降低体外受精率和卵母细胞的存活率。结论　Ａｓ２Ｏ３ 可以破坏卵母细胞的成熟、降低卵母细胞的受精能力, 对生殖细胞和生育能力有一定的毒性作用。     

Maternal and cord blood hormones in relation to birth size

Birth size has been associated with adult life diseases, but the endocrine factors that are likely involved are not established. We evaluated the associations of maternal and cord blood hormones with birth size in normal pregnancies, and examined possible effect modification by maternal height, on the basis of prior suggestive evidence. In a prospective study of normal singleton pregnancies in Boston, USA and Shanghai, China, maternal hormone levels at the 27th gestational week were available for 225 pregnancies in Boston and 281 in Shanghai and cord blood measurements for 92 pregnancies in Boston and 110 in Shanghai. Pearson partial correlation coefficients of log-transformed hormone levels with birth weight and length were calculated. Overall, positive correlations with birth weight were found for maternal estriol (r = 0.19; p < 0.001) and progesterone (r = 0.15; p < 0.001) and these associations were more evident among taller mothers. There was an inverse association of cord blood progesterone (r = ?0.16; p < 0.03) with birth weight. In Boston, cord blood IGF-1 was positively associated with birth weight (r = 0.22; p < 0.04) and length (r = 0.25; p < 0.02), particularly among taller mothers (r = 0.43 and 0.38, respectively; p < 0.02), whereas among taller mothers in Shanghai the associations of IGF-2 with birth size appeared to be at least as strong as those of IGF-1. In conclusion, maternal estriol and progesterone, and cord blood IGF-1 were positively correlated with birth size. All correlations tended to be more pronounced among offspring of taller mothers. Among taller mothers in Shanghai, IGF-2 appeared to be at least as strongly associated with birth size as IGF-1.     

Micronutrient intake during pregnancy in relation to birth size

Summary Background There exists very little information on possible effects on birth size of micronutrient intakes at levels that are usually encountered among pregnant women in developed countries. Aim of the study To examine the relation of the intake of 20 micronutrients with birth weight, placental weight, birth length and head circumference of the offspring. Methods In a cohort of 222 Caucasian women with singleton pregnancies in Boston, USA, diet during pregnancy was ascertained at the 27^th gestational week through a validated semi-quantitative food frequency questionnaire, covering also intake of dietary supplements. Micronutrient intakes were correlated with birth size parameters after adjustment for confounding variables, including total energy intake. Results Pantothenic acid, sodium and vitamin E were positively associated with all four birth size parameters. For pantothenic acid the association was statistically significant with respect to birth length, whereas for sodium with respect to head circumference and for vitamin E with respect to birth weight. In contrast, zinc was inversely associated with all four birth size parameters and the association was statistically significant with respect to head circumference. Conclusions In a moderately sized prospective study, we found evidence that pregnancy intake of pantothenic acid, vitamin E and sodium may be positively related with at least one of the studied birth size parameters, whereas an inverse association was found with respect to zinc intake. For the remaining 16 micronutrients, our findings indicate that they are not associated with birth size, at least within the range of intake encountered in this investigation. The results of this exploratory analysis need to be confirmed before pathophysiologic interpretations and generalizations are attempted.     

Family size and paternal unemployment in relation to myocardial infarction.

Men who had been in hospital for myocardial infarction (MI) were compared with other male patients in an attempt to provide evidence on the hypothesis linking MI with poverty in childhood followed by relative affluence. In each of three social class groupings MI patients came from larger families than controls, and a higher proportion of their fathers had been unemployed for more than a year during their childhood. This gives some support to the hypothesis that childhood poverty may be associated with an excess risk of MI. There was no obvious evidence of a greater improvement in social class status among the MI patients compared with the controls.     

未成熟卵体外成熟技术在卵巢高反应患者IVF-ET中的应用

目的:探讨未成熟卵体外成熟(IVM)技术在卵巢高反应患者体外受精-胚胎移植(IVF-ET)中的应用价值。方法:在IVF-ET促排治疗中,对双卵巢卵泡数过多,有可能发生卵巢过度刺激综合征(OHSS)或继续治疗可能发生重度OHSS的患者,根据其意愿即刻停药,全部取卵改行IVM治疗12个周期(A组)或取部分小卵泡改行IVM治疗,同时保留部分卵泡继续行IVF-ET常规治疗18个周期(B组)。小卵泡体外培养成熟后,通过卵胞浆内单精子注射(ICSI)获得受精卵并行胚胎移植或冷冻。统计分析未成熟卵的成熟率、卵母细胞的受精率、胚胎的发育情况及临床结局。结果:两组30个取卵周期,共获未成熟卵240个,经IVM、ICSI和体外培养后,成熟率、受精率、正常卵裂率及优质胚胎率分别为61.25%(147/240),77.55%(114/147),92.98%(106/114)和29.25%(31/106)。A组8例行IVM新鲜胚胎移植(8周期)4例临床妊娠,A、B两组有8例行IVM解冻胚胎移植(9周期)3例临床妊娠,已有3例分娩。A组12例无OHSS发生,促性腺激素用量少于B组,B组18例中3例有OHSS风险而取消胚胎移植。结论:对常规IVF促排周期中卵巢高反应患者及时改行IVM,可以避免周期取消及OHSS的发生,减少促排卵药物的使用量,同时获得较好的临床妊娠率。