Effect of insulin, transferrin and selenium and epidermal growth factor on development of buffalo oocytes to the blastocyst stage in vitro in serum-free, semidefined media

An Overview of Reactive Oxygen Species Damage Occurring during In Vitro Bovine Oocyte and Embryo Development and the Efficacy of Antioxidant Use to Limit These Adverse Effects

The in vitro production (IVP) of bovine embryos has gained popularity worldwide and in recent years and its use for producing embryos from genetically elite heifers and cows has surpassed the use of conventional superovulation-based embryo production schemes. There are, however, several issues with the IVP of embryos that remain unresolved. One limitation of special concern is the low efficiency of the IVP of embryos. Exposure to reactive oxygen species (ROS) is one reason why the production of embryos with IVP is diminished. These highly reactive molecules are generated in small amounts through normal cellular metabolism, but their abundances increase in embryo culture because of oocyte and embryo exposure to temperature fluctuations, light exposure, pH changes, atmospheric oxygen tension, suboptimal culture media formulations, and cryopreservation. When uncontrolled, ROS produce detrimental effects on the structure and function of genomic and mitochondrial DNA, alter DNA methylation, increase lipid membrane damage, and modify protein activity. Several intrinsic enzymatic pathways control ROS abundance and damage, and antioxidants react with and reduce the reactive potential of ROS. This review will focus on exploring the efficiency of supplementing several of these antioxidant molecules on oocyte maturation, sperm viability, fertilization, and embryo culture.

Antioxidants supplementation improves the quality of in vitro produced ovine embryos with amendments in key development gene expressions

The present study assessed the effects of supplementation of different antioxidants on oocyte maturation, embryo production, reactive oxygen species (ROS) production and expression of key developmental genes. In this study, using ovine as an animal model, we tested the hypothesis that antioxidant supplementation enhanced the developmental competence of oocytes. Ovine oocytes aspirated from local abattoir-derived ovaries were subjected to IVM with different concentrations of antioxidants [(Melatonin, Ascorbic acid (Vit C), alpha-tocopherol (Vit E), Sodium selenite (SS)]. Oocytes matured without any antioxidant supplementation were used as controls. The oocytes were assessed for maturation rates and ROS levels. Further, embryo production rates in terms of cleavage, blastocysts and total cell numbers were evaluated after performing in vitro fertilization. Real-Time PCR analysis was used to evaluate the expression of stress related gene (SOD-1), growth related (GDF-9, BMP-15), and apoptosis-related genes (BCL-2 and BAX). We observed that maturation rates were significantly higher in alpha-tocopherol (100 μM; 92.4%) groups followed by melatonin (30 μM; 89.1%) group. However, blastocyst rates in ascorbic acid (100 μM; 19.5%), melatonin (30 μM; 18.4%), alpha-tocopherol (100 μM; 18.2%), and sodium selenite (20 μM; 16.9%) groups were significantly higher (P 0.05) than that observed in the control groups. Total cell numbers in blastocysts in the melatonin, ascorbic acid and alpha-tocopherol groups were significantly higher than those observed in sodium selenite and control groups. ROS production was reduced in groups treated with melatonin (30 μM), vitamin C (100 μM), sodium selenite (20 μM) and α-tocopherol (200 μM) compared with that observed in the control group. Supplementation of antioxidants caused the alterations in mRNA expression of growth, stress, and apoptosis related gene expression in matured oocytes. The results recommend that antioxidants alpha-tocopherol (200 μM), sodium selenite (40 μM), melatonin (30 μM) and ascorbic acid (100 μM) during IVM reduced the oxidative stress by decreasing ROS levels in oocytes, thus improving embryo quantity and quality.

Enhancing the developmental competence of prepubertal lamb oocytes by supplementing the in vitro maturation medium with sericin and the fibroblast growth factor 2 - leukemia inhibitory factor - Insulin-like growth factor 1 combination

Poor development of oocytes from prepubertal animals is a major factor that hinders the application of the technology, juvenile in vitro embryo transfer (JIVET). The aim of this study was to explore the possibility of improving the developmental competence of prepubertal oocytes by supplementing the oocyte in vitro maturation (IVM) medium with antioxidants and cytokines. Effects of two antioxidants, melatonin and sericin, were first examined. The results showed that melatonin had no significant beneficial roles on the lamb oocyte development, while 0.5% sericin supplemented during IVM significantly increased the blastocyst rate of lamb oocytes (46.5% vs 19.2% in control, P < 0.05). Next, effects of two kinds of combined supplements, insulin-transferrin-selenium (ITS) and fibroblast growth factor 2(FGF2)-leukemia inhibitory factor (LIF)-insulin-like growth factor1 (IGF1)(FLI) were tested. The results indicated that addition of FLI, but not ITS, in the IVM medium, significantly improved the blastocyst development of lamb oocytes (43.9% in FLI group vs 21.6% in control, P < 0.05). Further comparison showed that the developmental competence of oocytes was not significantly different among supplementation with sericin or FLI alone or both, all of which generated similar outcomes of blastocyst yield to the supplementation with adult follicular fluid. Finally, 27 blastocysts produced from lamb oocytes matured in the presence of sericin and FLI were transferred into 18 recipients, of which 9 were pregnant. This study suggests that the developmental competence of prepubertal oocytes can be improved by supplementing IVM medium with relevant agents like sericin and cytokines.

Sodium Selenite Improves In Vitro Maturation of Bos primigenius taurus Oocytes

Selenium (Se) is an essential trace element with important functions in animals and whose deficiency is associated with reproductive failures. The aim of this study was to investigate the effect of Se concentrations during in vitro maturation (IVM) of Bos taurus oocyte within the reference ranges for Se status in cattle. For this purpose, Aberdeen Angus cumulus-oocyte complexes (COCs) were matured in IVM medium supplemented with 0, 10, 50, and 100 ng/mL Se (control, deficient, marginal, and adequate, respectively). The results demonstrated that marginal and adequate Se concentrations added during IVM increased viability and non-apoptotic cumulus cells (CC). Moreover, the addition of Se to culture media decreased malondialdehyde level in COC with all studied concentrations and increased total glutathione content in CC and oocytes with 10 ng/mL Se. On the other hand, total antioxidant capacity of COC, nuclear maturation, and the developmental capacity of oocytes were not modified by Se supplementation. However, 10 ng/mL Se increased hatching rate. In conclusion, supplementation with 10 ng/mL Se during in vitro maturation of Bos primigenius taurus oocytes should be considered to improve embryo quality.

Toxicological evaluation of 3-(4-Chlorophenylselanyl)-1-methyl-1H-indole through the bovine oocyte in vitro maturation model

The development of new bioactive molecules based on the molecular hybridization has been widely explored. In line with this, reliable tests should be employed to give information about the toxicology of these new molecules. In this sense, the use of in vitro tests is a valuable tool, especially the in vitro maturation of oocytes (IVM), which is an efficient resource to discover the potential toxicity of synthetic molecules. Thus, the aim of the present study was to evaluate the toxicological effects of the selenium-containing indolyl compound 3-(4-Chlorophenylselanyl)-1-methyl-1H-indole (CMI), on different quality parameters of bovine oocytes through the IVM. Different concentrations of the CMI compound (0, 25, 50, 100, 200 μM) were supplemented during the in vitro maturation process. After, the oocyte maturation rate, glutathione (GSH) levels, reactive oxygen species (ROS) levels, membrane, and mitochondrial integrity were evaluated. The results showed that the lowest concentration of CMI induced the highest GSH production (P < 0.05), an important marker of cytoplasmic quality and maturation. All treatments increased ROS production in relation to non-supplementation (P < 0.05). In addition, oocyte maturation was reduced only with the highest concentration of CMI (P < 0.05). Supplementation with CMI did not impact mitochondrial activity, integrity and cell membrane. To our knowledge, this is the first study that evaluates CMI on the oocyte in vitro maturation process. Importantly, our results did not find any toxic effect of CMI on bovine oocytes. CMI was efficient for cytoplasmic maturation by promoting an increase in the intracellular levels of glutathione.

The Growth of Preantral Follicles and the Impact of Different Supplementations and Circumstances: A Review Study with Focus on Bovine and Human Preantral Follicles

One of the most important concerns cancer survivors face is fertility. Current treatment modalities often result in damage to the reproductive system. Different options have been proposed to preserve the fertility of affected women, and many attempts have been made to improve their chance of childbearing after therapy. Cryopreservation of ovarian tissue and follicles before the onset of cancer treatment and then either transplantation of ovarian tissue or culture of ovarian tissue and individual follicles in vitro is a commonly cited approach. Extensive research is being done to design an optimal condition for the culture of ovarian follicles. Improving follicle culture systems by understanding their actual growth needs might be a crucial step toward fertility preservation in cancer patients. This review article will try to provide a summary of the role of different factors and conditions on growth of human and bovine preantral follicles in vitro.

The effect of pre-maturation culture using phosphodiesterase type 3 inhibitor and insulin, transferrin and selenium on nuclear and cytoplasmic maturation of bovine oocytes

This study aims to evaluate if a pre-maturation culture (PMC) using cilostamide as a meiotic inhibitor in combination with insulin, transferrin and selenium (ITS) for 8 or 24 h increases in vitro embryo production. To evaluate the effects of PMC on embryo development, cleavage rate, blastocyst rate, embryo size and total cell number were determined. When cilostamide (20 μM) was used in PMC for 8 or 24 h, 98% of oocytes were maintained in germinal vesicles. Although the majority of oocytes resumed meiosis after meiotic arrest, the cleavage and blastocyst rates were lower than the control (P 0.05) to the control. The deleterious effect of 20 μM cilostamide treatment for 24 h on a PMC was confirmed by lower cumulus cell viability, determined by trypan blue staining, in that group compared with the other groups. A lower concentration (10 μM) and shorter exposure time (8 h) minimized that effect but did not improve embryo production. More studies should be performed to determine the best concentration and the arresting period to increase oocyte competence and embryo development.

Supplementation of insulin-transferrin-selenium to embryo culture medium improves the in vitro development of pig embryos

Insulin, transferrin and selenium (ITS) supplementation to oocyte maturation medium improves the post-fertilization embryonic development in pigs. ITS is also commonly used as a supplement for the in vitro culture (IVC) of embryos and stem cells in several mammalian species. However, its use during IVC of pig embryos has not been explored. This study investigated the effect of ITS supplementation to IVC medium on the in vitro development ability of pig embryos produced by parthenogenetic activation (PA), in vitro fertilization (IVF) or somatic cell nuclear transfer (SCNT). We observed that ITS had no significant effect on the rate of first cleavage (P > 0.05). However, the rate of blastocyst formation in ITS-treated PA (45.3 ± 1.9 versus 27.1 ± 2.3%), IVF (31.6 ± 0.6 versus 23.5 ± 0.6%) and SCNT (17.6 ± 2.3 versus 10.7 ± 1.4%) embryos was significantly higher (P < 0.05) than those of non-treated controls. Culture of PA embryos in the presence of ITS also enhanced the expansion and hatching ability (29.1 ± 3.0 versus 18.2 ± 3.8%; P < 0.05) of blastocysts and increased the total number of cells per blastocyst (53 ± 2.5 versus 40.9 ± 2.6; P < 0.05). Furthermore, the beneficial effect of ITS on PA embryos was associated with significantly reduced level of intracellular reactive oxygen species (ROS) (20.0 ± 2.6 versus 46.9 ± 3.0). However, in contrast to PA embryos, ITS had no significant effect on the blastocyst quality of IVF and SCNT embryos (P > 0.05). Taken together, these data suggest that supplementation of ITS to the IVC medium exerts a beneficial but differential effect on pig embryos that varies with the method of embryo production in vitro.

Evaluation of cheetah and leopard spermatozoa developmental capability after interspecific ICSI with domestic cat oocytes

The ICSI procedure is potentially of great value for felids, and it has not been extensively studied in these species. The objectives of this work were to determine the best conditions for ICSI in the domestic cat (DC) to generate interspecific embryos by injecting cheetah (Ch) and leopard (Leo) spermatozoa. Firstly, DC oocytes were matured with insulin-transferrin-selenium (ITS) or without it (MM) and cultured using atmospheric (21%) or low (5%) oxygen tension after ICSI. The group ITS-5%O2 showed the highest blastocyst rate (p < 0.05), 20.9% vs 8.7%, 7% and 6.5%, for MM-21%O2 , MM-5%O2 and ITS-21%O2 , respectively. The best conditions were used to generate the interspecific embryos, together with ionomycin activation (Io) after ICSI. Interspecific embryos resulted in high rates of blastocysts that were not positively affected by Io activation: 32.6% vs 21% for Ch and Ch-Io, 9.8% vs 21% for Leo and Leo-Io, and 20% vs 17.4% for DC and DC-Io. We also evaluated DNA-fragmented nuclei of experiment 1 and 2 blastocysts, using TUNEL assay. The fragmented nucleus proportion was higher in the ITS-5%O2 group, 67.6%. Surprisingly, interspecific blastocysts showed the lowest fragmented nucleus proportion: 27% and 29.9% for Ch and Leo, respectively. We concluded that ITS and 5%O2 improve blastocyst formation in DC, although with a concomitant increase in DNA fragmentation. Most importantly, cheetah and leopard spermatozoa were able to generate blastocysts without artificial activation, which suggests that developmental capacity of wild felid spermatozoa can be evaluated by interspecific ICSI. This technique should be used to assist wild felid reproduction.

Insulin influences developmental competence of bovine oocytes cultured in α-MEM plus follicle-simulating hormone

The aim of this study was to evaluate the dose-response effect of insulin, plus follicle-simulating hormone (FSH) at a fixed concentration, in a serum-free defined culture medium (DCM) on the in vitro maturation of bovine cumulus-oocyte complexes (COCs). For oocyte nuclear maturation, the expression levels of GDF9, GLUT1, PRDX1 and HSP70.1 transcripts related to oocyte and embryo developmental competence were analysed. For in vitro maturation (IVM), cumulus-oocyte complexes from slaughterhouse ovaries were distributed into four groups based on insulin concentration added to serum-free DCM, which was composed of alpha minimum essential medium (α-MEM), as basal medium: (1) DCM control: 0 ng/ml; (2) DCM1: 1 ng/ml; (3) DCM10: 10 ng/ml; and (4) DCM100: 100 ng/ml. After IVM, the nuclear status of a sample of oocytes was analysed and the other oocytes were submitted for in vitro fertilization (IVF) and in vitro culture (IVC). Different concentrations of insulin did not affect significantly the nuclear maturation and cleavage rate (72 h post-insemination) across all groups. Blastocyst rate (192 h post-insemination) did not differ in DCM control (24.3%), DCM1 (27.0%) and DCM10 (26.3%) groups, but the DCM100 (36.1%) group showed a greater blastocyst rate (P 0.05) was observed at the different insulin concentrations. The results indicated that insulin added to DCM influenced levels of transcripts related to cellular stress (HSP70-1 and PRDX1) and oocyte competence (GDF9) in bovine oocytes and at higher concentrations enhanced blastocyst production.

Developmental competence and embryo quality of small oocytes from pre-pubertal goats cultured in IVM medium supplemented with low level of hormones, insulin-transferrin-selenium and ascorbic acid

The aim of this study was to test the effect of insulin-transferrin-selenium (ITS) and L-ascorbic acid (AA) supplementation and the hormonal level during in vitro maturation (IVM) of small oocytes from pre-pubertal goat on the blastocyst yield and quality. Concretely, we used four maturation media: conventional IVM medium (CM), growth medium (GM: CM+ITS+AA and low level of hormones), modified CM (mCM: CM with low level of hormones) and modified GM (mGM: CM+ITS+AA and normal level of hormones). Cumulus-oocyte complexes (COCs) were classified into two categories according to oocyte diameter: <125 μm and ≥ 125 μm. Large oocytes were matured 24 h in CM (Treatment A). Small oocytes were matured randomly in six experimental groups: Treatment B: 24 h in CM; Treatment C: 12 h in GM and 12 h in CM; Treatment D: 24 h in mGM; Treatment E: 12 h in mGM and 12 h in CM; Treatment F: 12 h in mCM and 12 h in CM; and Treatment G: 12 h in GM and 12 h in mGM. After IVM, oocytes were fertilized and cultured for 8 days. The blastocyst quality was assessed by the survival following vitrification/warming and the mean cell number. When different maturation media were combined, the blastocyst rate did not improve. The large oocytes produced the highest blastocysts yield. However, the culture of small oocytes in GM (53.3%) enhanced the post-warming survival of blastocysts compared to large oocytes matured in CM (35.7%). In conclusion, IVM of pre-pubertal goat small oocytes in GM would be useful to improve the quality of in vitro-produced blastocysts.

Unravelling the needs of singly in vitro-produced bovine embryos: from cumulus cell co-culture to semi-defined, oil-free culture conditions

Producing bovine in vitro embryos individually is a challenge as it generally leads to impaired embryo development. Earlier research optimised a single embryo in vitro production (IVP) protocol using serum, cumulus cells and oil during culture. As some of these factors are undesirable in certain circumstances, the present study investigated their necessity and possible interactions, and defined their role during single-embryo culture. Although the cumulus cell monolayer produced progesterone, it appeared not to be a key factor in supporting single-embryo development. Because in vitro culture in large medium volumes was shown to impair single-embryo development, two new oil-free culture protocols were tested. Using a 30-µL droplet of medium in 96-well plates with a small surface area resulted in comparable blastocyst rates to those obtained under oil. When serum was used, co-culture with cumulus cells seems necessary, leading to consistently high blastocyst rates. Finally, a serum-free, oil-free culture system using insulin, transferrin, selenium and BSA resulted in embryos with similar total cell numbers and apoptotic cell ratios, but blastocyst rates did not equal those obtained with serum and co-culture. This research additionally stresses the fact that specific interaction mechanisms between somatic cells and a developing in vitro embryo are far from unravelled.

Optimization of embryo culture conditions for increasing efficiency of cloning in buffalo (Bubalus bubalis) and generation of transgenic embryos via cloning

Cloning in bovine species is marred by low efficiency of blastocyst formation. Any increase in the efficiency of blastocyst formation upon nuclear transfer will greatly enhance the efficiency of cloning. In the present study, the effect of various media, protein sources, and growth factors on the development of cloned buffalo embryos was evaluated. Among various combinations tested, culture of cloned embryos in TCM-199 media on the feeder layer of Buffalo Oviductal Epithelial Cells (BOEC) in the presence of bovine serum albumin-free fatty acid (BSA-FFA) and leukemia inhibitory factor (LIF) provided most suitable environment for efficient development of cloned blastocysts. Under these conditions, we achieved a blastocyst formation rate of 43%, which is better than those reported previously. Because preimplantation embryonic development, in vivo, occurs in an environment of oviductal cells, the blastocysts generated by this method may presumably be more suitable for implantation and further development. Additionally, we generated green blastocysts from enucleated oocytes by transfer of nuclei from cells transfected with EGFP transgene, showing possibility of transgenesis via cloning in this species. To our knowledge, this is the first report regarding the production of transgenic cloned buffalo embryos and their developmental competence with respect to various media, cocultures, and supplements.

Factors affecting laboratory production of buffalo embryos: a meta-analysis

In vitro fertilization (IVF) provides an excellent and inexpensive source of embryos for carrying out basic research on developmental physiology, farm animal breeding, and for commercial applications. Meta-analysis of the results from different publications rather than a narrative review may provide a current status of this technology in buffalo (Bubalus bubalis). In order to gain an idea of the factors affecting the IVF in buffalo, a review of the various studies conducted on buffalo IVF and a meta-analysis of their findings was undertaken. More than 100 articles published from 1991 to 2008 were searched, and results were subjected to meta-analysis to determine the treatment variations without any bias. Thirty factors affecting in vitro embryo production in buffalo were considered. Initially, both fixed- and random-effect models were used. We did not observe any heterogeneity between the studies. Thereafter, all the studies were pooled using the fixed-effect model for analysis. Our analysis suggested that good buffalo oocytes with more than three to five cumulus layers recovered from large-sized follicles in cold seasons when cultured in TCM-199 supplemented with serum, follicle-stimulating hormone, and cysteamine resulted in maximum maturation rate and subsequent embryonic development after insemination. The values obtained in the current study may be considered for a simulation model in establishing a cost-effective suitable method for buffalo IVF in further planned research.

The effects of different concentrations of sodium selenite on the in vitro maturation of preantral follicles in serum-free and serum supplemented media

PURPOSE

This study was to investigate the effect of sodium selenite (SS) on in vitro maturation of mouse preantral follicles.

METHODS

The isolated preantral follicles were cultured in TCM 199 medium supplemented with different concentrations (0, 5, 10, 15 ng/ml) of SS and 3 mg/ml bovine serum albumin (BSA) or 5% Fetal Bovine Serum (FBS). The ovulation was induced by addition of 1.5 IU/ml human chorionic gonadotropin. The size and development of follicles and oocytes were assessed by calibrated eyepiece.

RESULTS

The survival rates of follicles in FBS supplemented groups containing 5 and 10 ng/ml SS (88.23%, 90.83%) were higher than other groups (P < 0.05 and P < 0.001 respectively). The mean diameter of follicles (199.84 +/- 15.58 microm) and the percentage of MII oocyte (33.08%) were higher in FBS supplemented group containing 10 ng/ml SS (P < 0.001).

CONCLUSION

The sodium selenite and FBS improve the in vitro growth and maturation of mouse preantral follicles.

Set up of a serum-free culture system for bovine embryos: embryo development and quality before and after transient transfer

It is well known that serum in culture medium negatively affects blastocyst quality. The objective of this work was to develop and test a serum-free culture medium which could improve embryo quality, measured by the resistance to freezing, lipid and glutathione content of the resulting blastocysts, as well as the ability of the blastocysts to elongate after transient transfer to recipient cows. In a first experiment we showed that adding a mixture of insulin, transferrin and selenium to serum-free Synthetic Oviduct Fluid medium (SOF-ITS) improved embryo development and quality. In the second experiment, the addition of BSA to SOF-ITS further improved blastocyst development. Moreover, a reduction in lipid content of morulae was observed in SOF-ITS-BSA by comparison with morulae cultured with serum (SOF-FCS). The resistance to freezing measured by hatching rates 24h post-thawing was also improved for blastocysts with a diameter between 160 and 180 microm cultured in SOF-ITS-BSA by comparison to those produced with serum. In order to evaluate the redox potential of the embryos, reduced glutathione content (GSH) was evaluated both before and after cryopreservation. A significant decrease in glutathione was observed after freezing, whatever the culture medium, but no difference was observed between culture conditions. Transient transfers were performed and elongated D-13 embryos were recovered. Elongation was more pronounced and the embryonic disk more often visible in embryos cultured in SOF-ITS-BSA than in embryos cultured with FCS. In conclusion, the serum-free system we developed to produce in vitro bovine embryos meets the developmental and qualitative requirements for a large-scale use.

Effect of low adapted temperature and medium composition on growth and erythropoietin (EPO) production by Chinese hamster ovary cells

Temperature and medium composition were changed with the aim of increasing growth and erythropoietin (EPO) production in EPO-producing Chinese hamster ovary (CHO) cells. We used the CHO cell line, IBE, and its derivative, CO5, which over-expresses the first two enzymes of the urea cycle, carbamoyl phosphate synthetase I (CPS I) and ornithine transcarbamoylase (OTC). When supplements were added to the medium at 33 degrees C, the growth of IBE and CO5 cells increased by 27% and 26%, respectively and the maximum yield of EPO was increased by 40% in both cell lines. The absolute EPO concentration in the CO5 cells was always 55-60% higher than in the IBE cells. In addition, when the two cell lines were continuously cultured with supplements at 33 degrees C until their growth rates approached those at 37 degrees C, the growth rates of both IBE and CO5 cells increased by 54% and their maximum EPO levels increased by up to 73% and 56%, respectively. Therefore, the growth and EPO expression levels of CO5 cells increased 2.2-fold and 2.6-fold, respectively, compared to those of the IBE cells. These results indicate that adaptation to lower temperature as well as medium supplementation could be important for improving cell growth and EPO production.

Developmental competence and post-thaw survivability of buffalo embryos produced in vitro: effect of growth factors in oocyte maturation medium and of embryo culture system

The present study was conducted to examine the effects of supplementation to IVM medium of epidermal growth factor (EGF), fibroblast growth factor (FGF) and vasoactive intestinal peptide (VIP) along with pregnant mare serum gonadotrophin (PMSG) on oocyte maturation and cleavage of buffalo embryos (experiment 1). The developmental competence of cleaved embryos cultured in either a complex co-culture system (TCM-199+10% serum+oviduct cell monolayer) or defined media (a) modified form of synthetic oviductal fluid (mSOF) was evaluated (experiment 2). The post-thaw morphology and survivability of frozen blastocysts developed from embryos cultured either in complex or defined medium was compared (experiment 3). Aspirated oocytes were cultured in maturation medium (TCM-199+PMSG (40 IU/ml-control)) supplemented with EGF (20 ng/ml), FGF (20 ng/ml) and VIP (20 ng/ml), either alone or in combination, in a CO(2) incubator at 38.5 degrees C for 24h. Maturation rate was assessed and oocytes were inseminated in vitro with frozen-thawed sperm processed in Brackett and Oliphant (BO) medium. The cleaved embryos were cultured either in complex co-culture system or mSOF. Results suggested that EGF had more beneficial effect on buffalo oocyte maturation, and embryo cleavage than FGF. Addition of VIP to the oocyte maturation medium did not improve the results. Blastocyst yields from buffalo oocytes were significantly higher in a complex co-culture system than in defined media (mSOF) when oocytes were matured in presence of EGF either alone or in combination with FGF and VIP. The mean percent of morphologically normal blastocysts after thawing and their survivability were significantly higher in blastocysts obtained from embryos cultured in mSOF than those cultured in complex co-culture system.

Production of buffalo (Bubalus bubalis) embryos in vitro: premises and promises

Techniques for in vitro production (IVP) of buffalo embryos adopting the procedures developed in cattle have received increasing interest in the recent times. A high oocyte maturation, fertilization and cleavage rate and a low rate of blastocyst yield and calving following transfer of in vitro produced buffalo embryos have been obtained. The efficiency of IVP in buffalo is much lower than that in cattle. Several problems need to be resolved before IVP technology can be used regularly in buffalo breeding. This review attempts to present an overview of the different techniques used in buffalo to produce transferable embryos in vitro, namely in vitro maturation and fertilization of immature oocytes and in vitro development of the resulting cleaved embryos to the blastocyst stage before transfer. The problems associated with IVP, the possible solutions and the new biotechniques linked to IVP are discussed.