scholarly journals The level of melatonin in the blood and follicular fluid in women with infertility in the program of assisted reproductive technologies and the effectiveness of its application

2021 ◽  
Vol 25 (2(98)) ◽  
pp. 119-124
Author(s):  
V. Yuzko
Keyword(s):  
Follicular Fluid ◽  
Assisted Reproductive Technologies ◽  
Reproductive Technologies ◽  
Control Group ◽  
Healthy Children ◽  
Art Programs ◽  
The Third ◽  
Women In Art ◽  
Ovulation Stimulation ◽  
Female Donor

Objective was to investigate the level of melatonin in the blood and follicular fluid in women treated with infertility by ART method and evaluate the effectiveness of melatonin in their preparation for programs.Material and methods. 89 women were examined. The first (control) group included 13 healthy women oocyte donors who gave birth to their own healthy children, the second group - 33 women with infertility, who two weeks before and during ovulation stimulation were taken simultaneously at the same time before bedtime 3 mg of the drug "Vita-melatonin" produced by "Kyiv Vitamin Plant", the third group - 43 women with infertility who did not take the drug melatonin during ovulation stimulation. ELISA (Germany) reagent kits were used to determine melatonin levels. Melatonin levels were determined in blood plasma, and follicular fluid obtained during the puncture at 9:00 am.Results. The level of melatonin in the blood of female donor oocytes was 130.85 ± 16.91 pg/ml. This rate in the blood of women who used the drug melatonin before and during ovulation stimulation was significantly higher than in the blood of women who did not take the drug (respectively, 143.06 ± 14.87 pg/ml and 123.40 ± 12.65 pg / ml, p <0.05), and in the follicular fluid there was an inverse relationship: the level of melatonin in women of the first group was 97.15 ± 8.69 pg / ml, the second group - 39.46 ± 4.52 pg/ml, which is significantly less (p <0.05), the third group - 62.34 ± 3.94 pg / ml, which is almost twice more (p <0.05) compared with women who took melatonin, but less (p <0.05) compared with the first group. The frequency of pregnancy on transfer in patients of the first group was 80.0 ± 11.01%, in women of the second group probably less - 60.6 ± 8.25% (p <0.05), but also probably higher compared to women in the third group - 45.0 ± 7.62% (p <0.05). A similar pattern was observed by us on the onset of pregnancy in general: in the first group - 100.0%, in the second - 68.9 ± 8.05% (p <0.05), in the third - 60.5 ± 7.47% (p> 0.05).Conclusions. The low level of melatonin in the follicular fluid obtained by us in women who underwent ovulation stimulation in ART programs in the treatment of infertility requires further scientific interpretation. At the same time, the best results of pregnancy in women in ART programs who took melatonin in preparation are encouraging.

scholarly journals Comparative characteristics of patients with infertility when applying melatonin in complex preparation for assisted reproductive technologies

2021 ◽  
Vol 25 (3 (99)) ◽  
pp. 149-156
Author(s):  
V. Yuzko ◽  
O. Yuzko
Keyword(s):  
Ovarian Reserve ◽  
Assisted Reproductive Technologies ◽  
Ultrasound Examination ◽  
Reproductive Technologies ◽  
Control Group ◽  
Antral Follicles ◽  
The Third ◽  
Significant Difference ◽  
Ovulation Stimulation ◽  
Infertility Patients

Оbjective of the study was to conduct a retrospective comparative characterization of patients with infertility who took or did not take melatonin with assisted reproductive technologies (ART).Materials and methods. In our study, we examined 89 women. The first (control) group included 13 healthy women oocyte donors who got pregnant on their own and gave birth to their own healthy children, the second group - 33 patients with infertility, who took 3 mg of the preparation "Vita-melatonin" produced by "Kyiv Vitamin Plant" at the same time before bedtime, two weeks before and during ovulation stimulation, the third group - 43 patients with infertility who did not take melatonin preparation before and during ovulation stimulation. There were no women who worked night shifts among the patients. Medical documentation of women of the control group and those with infertility, data of gynecological, ultrasound examination, hormones blood were analyzed. Ultrasound examination of the pelvic organs was performed on all patients with the device "Mindray DC-80 X-Insight", and measurements were performed using a transvaginal sensor. The thickness and structure of the endometrium were evaluated, and the number of antral follicles (NAF) ranging in size from 2 to 10 mm was counted in each ovary. All patients were tested for serum levels of the anti-mullerian hormone (AMG), follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), prolactin (PRL), progesterone (P), thyroid-stimulating hormone (TSH), triiodothyronine (T4).Results. The average age of women in the first (control) group was 27.08 ± 12.38 years, the second (taking melatonin) - 33.12 ± 8.18 years, the third (not taking melatonin) - 30.95 ± 7.07 years > 0.05), i. e. the age of the patients of the examined groups was equal. It should be noted that in the studied patients of both groups, the occurrence of primary infertility exceeded secondary infertility 2.7 times in the second group (p < 0.05) and 1.7 times in the third (p < 0.05). Infertility factors such as reduced ovarian reserve, habitual miscarriage and infertility of unknown origin were more common in patients of the second group, and endometriosis, tubal factor and male factor in the third, although the difference was not significant. The available extragenital pathology did not differ in the patients of the examined groups. The number of antral follicles was significantly higher in both ovaries of women in the control group compared with patients of the second and third groups. While the thickness of the endometrium did not differ significantly in groups, although in women of the control group it was slightly less. Regarding the study of hormonal status, it should be noted that we did not find a significant difference in the levels of hormones in the blood of women we examined. Exceptionally, there was a significant difference (p < 0.001) in progesterone content between the second (0.62 ± 0.052 nmol/l) and third (181.63 ± 13.87 nmol/l) groups. Also, the patients of the third group had significantly (p < 0.05) higher levels of FSH in blood (8.25 ± 0.63 mUn/ml) compared with the control group (4.93 ± 0.69 mUn/ml).Conclusions. The examined women in the control group, as well as infertility patients who received melatonin two weeks before the expected menstruation and during ovulation stimulation, and infertility patients who did not receive this preparation in similar programs, did not differ in age, occurrence of primary and secondary infertility, the factor that led to infertility, concomitant extragenital pathology, ovarian reserve and hormone levels of the reproductive panel. That is, they were equal in our study.

Effectiveness and outcomes of embryo cryopreservation programs in assisted reproductive technologies

2014 ◽  
Vol 63 (4) ◽  
pp. 39-46 ◽  
Author(s):  
Yana Nikolayevna Kravchuk ◽  
Alla Stanislavovna Kalugina ◽  
Olga Vladimirovna Bystrova ◽  
Svetlana Aleksandrovna Shlykova
Keyword(s):  
Embryo Transfer ◽  
Assisted Reproductive Technologies ◽  
Negative Impact ◽  
Perinatal Outcomes ◽  
Reproductive Technologies ◽  
Embryo Cryopreservation ◽  
Control Group ◽  
Fresh Embryo Transfer ◽  
Art Programs ◽  
Thawed Embryo Transfer

Background. Embryo cryopreservation is an essential part of ART programs today. In recent years vitrification method is used increasingly widely. Purposes and tasks. To compare the effectiveness of ART programs using vitrified and fresh embryos, as well as different endometrial preparation regimes for frozen\thawed embryo transfer (modified natural cycle (MNC) and the preparatory hormone therapy(PHT)). To analyze the course of pregnancy and perinatal outcomes after vitrified embryo transfer. Materials and methods. We prospectively assessed the ART programs effectiveness and perinatal outcomes in 153 patients (I group), who underwent vitrified embryo transfer in 2011-2013 year. To prepare the endometrium for thawed embryo transfer in 83 patients PHT (Ia subgroup) and MNC in 70 patients (Ib subgroup) were used. Control group consisted of 70 patients, who underwent fresh embryo transfer. Results. The clinical pregnancy rate, birth rate and “take home baby” rate were not significantly different between the I (47,5 %; 30,9 %; 30,9 %) and II (53,0 %; 34,9 %; 32,5 %) groups, and between Ia (48,3 %; 28,4 %; 28,4 %) and IIb (46,6 %; 34,1 %; 34,1 %) subgroups. Complications during pregnancy and delivery, birthweight, length, Apgar score, congenital malformation rate did not differ significantly after vitrified and fresh embryo transfer. Conclusion. Vitrification is an effective method to achieve clinical results, comparable to native cycles. Application of PHT and MNC results in similar clinical outcomes. Transfer Vitrified embryo transfer does not have a negative impact on obstetric and perinatal outcomes when compared with native cycles.

176 IN VITRO MATURATION OF DOG OOCYTES IN CANINE FOLLICULAR FLUID

2014 ◽  
Vol 26 (1) ◽  
pp. 202
Author(s):  
K. Reynaud ◽  
S. Canguilhem ◽  
S. Thoumire ◽  
S. Chastant-Maillard
Keyword(s):  
Follicular Fluid ◽  
In Vitro Maturation ◽  
Assisted Reproductive Technologies ◽  
Cumulus Cells ◽  
Reproductive Technologies ◽  
Control Group ◽  
Limiting Factor ◽  
Cytoplasmic Maturation

In the canine species, assisted reproductive technologies, especially in vitro maturation (IVM) and IVF, are still ineffective. The main limiting factor remains the immaturity of the oocytes collected from anestrus ovaries. The ability of an oocyte to reach the MII stage in vitro is linked to the diameter of its follicle and anestrus oocytes, collected from small (<1 mm) follicles, are profoundly immature (De Lesegno et al. 2008). The objective of this study was to improve cytoplasmic quality by mimicking in vivo conditions; that is, to test the effect of pure preovulatory follicular fluid (FF) on survival and IVM rates of anestrus dog oocytes, in order to improve the nuclear and cytoplasmic maturation of these immature oocytes. Follicular fluids samples were collected from 54 Beagle bitches at 2 stages: before the LH peak (n = 23 bitches) and after the LH peak (n = 31 bitches). Only follicular fluid samples from large (>4 mm) follicles were collected and pooled by stage. Control oocytes were matured in 20% FCS/M199 medium. Groups of 5 oocytes were in vitro matured in 30 μL of follicular fluid, in half-area 96-well plates (5% CO2, 38°C). After 72 h of IVM, oocytes were denuded, fixed, and stained for DNA and tubulin before observation by confocal microscopy, and nuclear stages were classified as GV-A to GV-E, MI, and MII (Reynaud et al. 2012). A total of 460 oocytes were collected from 13 anestrus bitches and allocated to either the control medium (n = 155), the Pre-LH FF (n = 145) or the Post-LH FF (n = 160) groups. After 72 h of IVM, the morphology of the cumulus–oocyte complexes (COC) in the post-LH group was different from that of the others: cumulus cells appeared more compact and darker. Analysis of the nuclear stages showed that the degeneration rate was significantly higher (P < 0.05) in the post-LH group (58.7%) than in the pre-LH (40.9%) or in the control group (34.4%). No significant differences (P > 0.05) were observed between the 3 groups in the rate of immature GVA-B oocytes (36.4, 28.5, and 25.3% in the control, Pre-LH, and Post-LH groups, respectively), in the rate of meiotic resumption (GV-C/D/E, MI, MII stages, 44.4, 51.9, and 38.7% in the control, Pre-LH, and Post-LH groups, respectively). Metaphase II rates were not significantly different (12.1, 8.6, and 4.8% in the control, Pre-LH, and Post-LH groups, respectively). In conclusion, canine COC may survive when exposed to IVM in pure follicular fluid, but the degeneration rate was higher in the post-LH group. The presence of follicular fluid did not inhibit meiosis resumption, but did not significantly improve IVM rates. To better mimic in vivo conditions, IVM in a sequence of media, such as IVM in follicular fluid followed by IVM in oviducal fluid remains to be tested.

scholarly journals Assessment of Oxidative Stress Changes in Serum and Follicular Fluid in Relevance to GnRH rival Protocol in Iraqi Infertile Ladies Undergoing ICSI

2019 ◽  
Vol 1 (5) ◽  
Author(s):  
Fatimah Abdulrazaq Raheem ◽  
Hayder A. L. Mossa ◽  
Wasan A. Abdulhamed ◽  
Liqaa R. Altamimi
Keyword(s):  
Follicular Fluid ◽  
Assisted Reproductive Technologies ◽  
Reproductive Technologies ◽  
Control Group ◽  
Oxidative Potential ◽  
Significant Difference ◽  
Stress Changes ◽  
Antagonist Group ◽  
Antagonist Protocol

Background: Literary works about the role of rival convention in relationship with oxidative pressure are opposing and there is no reasonable agreement in distributed ripeness articles about the role of opponent reproduction convention with this respect. In reality, a few creators support the presence of expanded oxidative initiated oocyte harm in ladies experiencing ART's; regardless, others have denied such a perception. Hence, the present investigation was arranged so as to think about the conceivable oxidative or hostile to oxidative potential controlled by foe convention. Aim of the study: The aim of the current study was to evaluate the serum and follicular ROS concentration in women undergoing ICSI contrasted between two groups, one receiving conventional antagonist protocol and the other receiving conventional agonist protocol. Patients and Methods: The current case control study included two groups of subfertile women. The study group included 57 women receiving antagonist protocol, whereas, the control group included 10 subfertile women receiving agonist protocol. The study was carried out at High Institute of Infertility Diagnosis and Assisted Reproductive Technologies at Al- Nahrain University. The study started on April 2018 and extended to March 2019. Women in both groups were subjected to ICSI procedure according to procedures and techniques adopted in High Institute of Infertility Diagnosis and Assisted Reproductive Technologies at Al- Nahrain University with a single basic difference concerning the ovarian stimulation protocol. Results: Overall clinical pregnancy rate was 44.7 % being significantly higher in antagonist group in comparison with agonist group 50.9 % versus 10.01 %, respectively (P = 0.019). There was no significant difference in the concentration of ROS at cycle day 2 between antagonist and agonistgroups (P = 0.561). There was highly significant difference in the serum concentration of ROS at day of ova pickup between antagonist and agonist groups (P = 0.009); being less in antagonistgroup and there was highly significant difference in the follicular fluid concentration of ROS between antagonist and agonist groups (P = 0.003); being less in antagonist group. Conclusions: Antagonist protocol is associated with significantly higher positive pregnancy outcome in comparison with agonist protocol because of the anti-oxidant effect attributed to antagonist use.

scholarly journals The effect of excess body weight and obesity on the effectiveness of assisted reproductive technologies programs

2018 ◽  
Vol 67 (2) ◽  
pp. 32-39
Author(s):  
Manizha R. Mahmadaliyeva ◽  
Igor Yu. Kogan ◽  
Dariko A. Niauri ◽  
Irina D. Mekina ◽  
Alexander M. Gzgzyan
Keyword(s):  
Assisted Reproductive Technologies ◽  
Reproductive Technologies ◽  
Normal Weight ◽  
Assistive Technologies ◽  
Control Group ◽  
Excess Body Weight ◽  
Obese Women ◽  
Art Programs ◽  
Overweight Women ◽  
Group I

The purpose of the study. To determine the main indicators of the effectiveness of IVF programs in over-weight and obese patients. Based on the Research Institute of obstetrics, gynecology, and reproductology D.O. Ott, we conducted an analysis involving women aged 18–39 years who were treated in the IVF program in the department of assistive technologies in infertility treatment. The study included 97 patients who met the selection criteria. The patients were categorized into three groups: group I, 33 obese women (body mass index (BMI) ≥ 30.8 kg/m2); group II, 34 overweight women (BMI = 25 to 29.9 kg/m2); and the control group, 30 normal weight patients (BMI = 18 to 24.9 kg/m2). As a result, the efficiency of ART programs decreased significantly in women of group I, owing to the weaker response of the ovaries to the stimulation of superovulation, which causes an increased gonadotropin demand to stimulate  ovulation.

Mechanism of the adverse effect of hyaluronidase used for oocyte denudation on early development of bovine embryos

Zygote ◽  
2021 ◽  
pp. 1-5
Author(s):  
Shiori Ashibe ◽  
Kanade Irisawa ◽  
Ken Yokawa ◽  
Yoshikazu Nagao
Keyword(s):  
Treatment Group ◽  
Assisted Reproductive Technologies ◽  
Cumulus Cells ◽  
Reproductive Technologies ◽  
Control Group ◽  
Free Calcium ◽  
Parthenogenetic Development ◽  
Early Embryos ◽  
Bovine Oocytes

Summary Hyaluronidase is widely used in animal and human assisted reproductive technologies (ARTs) to remove cumulus cells around oocytes. However, adverse effects of hyaluronidase treatment, such as increased rates of degeneration and parthenogenesis, have been found after treatment of human and mouse oocytes. Currently, the mechanism(s) of the detrimental effects are unclear. The present study was initiated to identify the mechanism of adverse responses to hyaluronidase treatment in bovine oocytes and early embryos. Cumulus cells were removed from cumulus–oocyte complexes (COCs) with or without hyaluronidase and the oocytes were subjected to intracytoplasmic sperm injection (ICSI) or in vitro fertilization (IVF). Significantly lower rates of blastocyst formation were obtained in the hyaluronidase treatment group after ICSI (22.4%) and IVF (21.2%) compared with the non-hyaluronidase control groups: 36.1% after ICSI and 30.4% after IVF. Next, we examined the effect of hyaluronidase on parthenogenetic development rates and on the cytoplasmic levels of free calcium ions (Ca2+), reactive oxygen species (ROS) and reduced glutathione (GSH). No differences in parthenogenesis rates were found between treated and untreated groups. Ca2+ levels in oocytes from the hyaluronidase treatment group indicated using mean fluorescence intensity were significantly higher (68.8 ± 5.3) compared with in the control group (45.0 ± 2.5). No differences were found in the levels of ROS or GSH between the treated and untreated groups. We conclude that hyaluronidase might trigger an increase in Ca2+ levels in oocytes, resulting in a decreased potential for normal embryonic development.

Genetic polymorphisms of reproductive hormones and their receptors in assisted reproduction technology for patients with polycystic ovary syndrome

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yulia A. Koloda ◽  
Yulia V. Denisova ◽  
Natalia M. Podzolkova
Keyword(s):  
Polycystic Ovary Syndrome ◽  
Assisted Reproductive Technologies ◽  
Polycystic Ovary ◽  
Ovarian Response ◽  
Reproductive Technologies ◽  
Reproductive Hormones ◽  
Current Data ◽  
Nucleotide Polymorphisms ◽  
Ovary Syndrome ◽  
Art Programs

Abstract Polycystic ovary syndrome (PCOS) is one of the most common endocrinopathies in women of childbearing, which is defined by the accumulation of multiple, small fluid-filled ovarian cysts without the selection of a single dominant follicle. Most PCOS phenotypes are characterized by the absence of spontaneous ovulation, resistance toward ovulation inductors, the production of a large immature oocytes number, and the high prevalence of ovarian hyperstimulation syndrome, resulting in reduced assisted reproductive technologies (ART) programs effectiveness. The review analyses current data about the relationship between polymorphism genotypes of KISS genes, follicle stimulating hormone (FSH), luteinizing hormone (LH), anti-Müllerian hormone (AMH) and their receptors genes, gonadotropin-releasing hormone (GnRH), estrogen, and progesterone receptors genes, the PCOS risk and the features of ovarian response to stimulation during ART cycles. The use of single nucleotide polymorphisms (SNPs) as prognostic markers of ART programs outcomes would provide a personalized approach to the drugs and doses choice for ovarian stimulation and significantly increase the chance of pregnancy.

The birth of a healthy child in the assisted reproductive technologies program after autologous co-culture of embryo with cumulus cells and a new CAT transfer technology. Case report

GYNECOLOGY ◽  
2021 ◽  
Vol 23 (3) ◽  
pp. 270-274
Author(s):  
Gunai R. Asfarova ◽  
Veronika I. Smol'nikova ◽  
Natalia P. Makarova ◽  
Iuliia S. Drapkina ◽  
Anastasiia P. Sysoeva ◽  
...  
Keyword(s):  
Embryo Transfer ◽  
Healthy Child ◽  
Assisted Reproductive Technologies ◽  
Cumulus Cells ◽  
Reproductive Technologies ◽  
Biologically Active ◽  
Human Embryos ◽  
Implantation Failure ◽  
Recurrent Implantation Failure ◽  
Art Programs

Cumulus cells are essential during oocytes growth and development, as well as during their maturation and fertilization. Research results have shown that embryo co-cultivation with autologous cumulus cells increases the frequency of blastocyst formation, and also improves the effectiveness of ART programs. Embryo transfer in such programs is recommended to be carried out using the CAT technology (Cumulus-Aided embryo Transfer), which includes embryo cultivation on a layer of cumulus cells and embryo transfer with a certain amount of diluted cumulus cells. Patient G., 38 years old, came to the department with infertility for 15 years and recurrent implantation failure in history. The patient had ART program with autologous co-cultivation of embryos with cumulus cells and a new CAT transfer technology. The patient fell pregnant and gave birth to a healthy child. Autologous cumulus cells can be a source of biologically active substances and improve embryological parameters and implantation rate in ART programs. Embryo co-cultivation with cumulus cells is especially important for patients with recurrent implantation failure. This technique can become an alternative for optimizing human embryos culturing.

scholarly journals INFLUENCE ON THE OUTCOME OF ART PROGRAMS OF FROZEN-THAWED BLASTOCYSTS EXPANDED ON FIVE OR SIX DAY

2021 ◽  
pp. 68-75
Author(s):  
A.O. Polumiskova ◽  
S.I. Tevkin ◽  
T.M. Jussubaliyeva ◽  
M.S. Shishimorova
Keyword(s):  
Pregnancy Rate ◽  
Assisted Reproductive Technologies ◽  
Reproductive Technologies ◽  
Clinical Pregnancy ◽  
Clinical Pregnancy Rate ◽  
Miscarriage Rate ◽  
Art Programs ◽  
Group A ◽  
The Difference ◽  
Group B

In order to increase the effectiveness of assisted reproductive technologies (ART) programs, it is essential to improve and develop conditions of embryo culture prior its transfer or cryopreservation of expanded blastocysts on the day 5 or 6. The aim of the study was to assess the effect of human blastocysts’ expansion timing on clinical pregnancy rate (CPR), miscarriage rate (MR) and take-home baby rate (THBR) in frozen-thawed cycles during ART programs. The study involved 2275 frozen embryo transfers (FET) of blastocysts expanded on the day 5 (group A) and 170 FET of blastocysts expanded on the day 6 (group B). The pregnancy rates in both groups were 50.8% and 46.5% respectively. There were no statistically significant differences in clinical pregnancy rate 37.4% and 37.0%, miscarriage rate 26.0% and 21.5% in both groups, respectively. THBR, as the main indicator of efficiency in the programs with transfer of post thawed expanded blastocysts on the day 5 (group A) or 6 (group B) were 36.5% and 35.2%, respectively (the difference is insignificant). In conclusion, in cryoprotocols the day of blastocyst expansion (day 5 or 6 of development) does not statistically affect PR, MR and THBR. In FET programs the quality of blastocyst (excellent and good) should be prioritized regardless of the day of cryopreservation.

198 Comparison of invitro production of bison and cattle embryos and effect of L-carnitine during maturation of bison oocytes

2020 ◽  
Vol 32 (2) ◽  
pp. 227
Author(s):  
A. R. Moawad ◽  
H. Benham ◽  
J. P. Barfield
Keyword(s):  
Assisted Reproductive Technologies ◽  
Cell Mass ◽  
Reproductive Technologies ◽  
T Test ◽  
Control Group ◽  
Chi Square ◽  
Important Species ◽  
Developmental Potential ◽  
Cell Numbers ◽  
Frozen Semen

Bison are an important species in North America, both economically and culturally. Although assisted reproductive technologies have been applied to preserve the genetic diversity of bison, development of these technologies remains limited for this species. The objective of the present study was to compare success rates of oocyte maturation, fertilization, and embryo development invitro in bison versus cattle (experiment 1). Cumulus-oocyte complexes obtained from abattoir-derived cattle and bison ovaries were matured, fertilized with frozen semen, and cultured invitro using standard procedures (De La Torre-Sanchez et al. 2006 Reprod. Fertil. Dev. 18, 585-596). At least three replicates were repeated for each experimental group. Oocyte recovery rate was lower in bison than in cattle (4.3; 2797/699 vs. 6.7; 4138/677, oocyte/ovary; P&lt;0.01, t-test). Nuclear maturation (oocytes at MII, 23h post-IVM) and fertilization rates (oocytes with 2 pronuclei 18h post-insemination; p.i.) evaluated by Hoechst stain were lower (P&lt;0.01, chi-square) for bison (65.1%; 56/86 and 32.7%; 18/55, respectively) than for cattle (88.3%; 83/94 and 70.9%; 39/55, respectively). Polyspermy tended to be higher in bison than in cattle (12.7% vs. 3.6%, P=0.08). The percentages of 2-cell embryos tended to be lower in bison than in cattle (13.5% vs. 25.0%, P&gt;0.05) at 24h p.i. but by 30h p.i., this difference increased (33.7% vs. 67.0%, P&lt;0.01, chi-square). Cleavage (Day 3) and blastocyst (Day 7) rates were lower (P&lt;0.01, chi-square) for bison (58.2%; 280/481 and 14.6%; 70/481, respectively) than for cattle (90.8%; 405/446 and 22.9%; 102/446, respectively). Total cell number (74.9±4.8 vs.114.2±5.8), trophectoderm cell numbers (57.9±4.6 vs. 89.2±4.8) and inner cell mass cell numbers (16.9±2.3 vs. 25±1.9) as determined by Hoechst and propidium iodide were all lower (P&lt;0.01, t-test) in bison than in cattle blastocysts. To improve oocyte competence in bison, we evaluated effects of L-carnitine (LC) supplementation during IVM on developmental potential of bison oocytes (experiment 2). Cumulus-oocyte complexes were matured in IVM medium supplemented with 0, 0.15, 0.3, 0.6, or 1.2mgmL−1 LC. No differences were observed in cleavage rates of control (0mgmL−1 LC) and LC-treated groups (values ranged from 60.0 to 66.4%). Interestingly, a dose-dependent increase in blastocyst development was found with the lowest value recorded in control group (10.4%; 14/134) and the highest value in the 1.2mgmL−1 LC supplemented group (22.2%; 23/105; P&lt;0.01, chi-square, n=4). Adding 1.2mgmL−1 LC to the IVM medium improved the percentage of hatching blastocysts compared with the control. In conclusion, bison oocytes exhibited lower invitro maturation, fertilization, and developmental rates compared with cattle oocytes using our system, and bison embryos were delayed in the timing of first cleavage. L-Carnitine supplementation during IVM of bison oocytes improved the preimplantation development and quality of invitro-produced blastocysts.

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