Oviductal fluid and growth factors failed to enhance development of porcine embryos

Porcine embryos (1-, 2- and 4-cell) were cultured in a basal medium consisting of Krebs-Ringer bicarbonate buffer supplemented with oviductal fluid and several growth factors and observed for further development. Oviducts were flushed at either 48 h (Experiment 1) or 96 h (Experiment 2) after the onset of estrus. Observations were made every 48 h (Experiment 1) or 12 h (Experiment 2) until failure of the embryos to develop for 2 consecutive observations. Embryos were scored 0 = no development, 1 = cleavage, 2 = morula, 3 = blastocyst, or 4 = hatched blastocyst. In the first experiment, development of 1-, 2- and 4-cell embryos (n=282) in the basal medium supplemented with oviductal fluid (4:1) or 3 sets of growth factors, was less or equal to one cleavage stage. Those embryos cultured in the basal medium supplemented with bovine serum albumin (fatty acid free) (BSA) advanced to the blastocyst stage. In the second experiment, 96 h aged embryos (n=142) were cultured in the basal medium supplemented with IGF-1 and - 2 and EGF, or with BSA alone or with BSA and the three growth factors. In the treatments without BSA, the embryonic development was less than one cleavage, whereas in those treatments with BSA, embryos advanced beyond hatching and began to expand. We conclude that for culture of porcine embryos, supplementation with several growth factors or with oviductal fluid, in the concentration used in this study, was of little benefit at this stage of development. However, the type of BSA significantly affected development. More than 90% of the embryos reached the morula and blastocyst stages in medium than included BSA (fatty acid free).     

In vitro development of day-2 equine embryos co-cultured with oviductal explants or trophoblastic vesicles

This study compared the in vitro development of Day-2 equine embryos co-cultured with either trophoblastic vesicles or oviductal explants. Embryos were collected surgically from the oviducts of pony mares 2 d after ovulation and assessed for stage of development. Culture medium was Ham's F12 and Dulbecco's Modified Eagle's Medium (50:50 v/v) in a humidified atmosphere of 5% CO(2) in air at 38.5 degrees C with either trophoblastic vesicles or oviductal explants. The quality score of embryos was assessed daily. After 4 d in culture, embryos were stained (Hoechst 33342) and evaluated with epifluorescence to determine the number of nuclei present. Six of seven embryos co-cultured with oviductal exmplants developed to the morula/blastocyst stage, while four of seven embryos co-cultured with trophoblastic vesicles developed to the morula stage. More (P = 0.1) embryos co-cultured with oviductal explants reached the blastocyst stage than embryos co-cultured with trophoblastic vesicles (3 7 vs 0 7 , respectively). The number of cells was higher (P = 0.1) for embryos co-cultured with oviductal explants than for embryos co-cultured with trophoblastic vesicles (162.6 +/- 32 vs 87.3 +/- 28, respectively). The number of cells for embryos co-cultured with either oviductal explants or trophoblastic vesicles appeared to be lower than for embryos matured in vivo that were recovered from the uterus at Day 6 (378, 399, >1000). The co-culture of early equine embryos in a completely defined medium with either trophoblastic vesicles or oviductal explants can support development to at least the morula stage. The co-culture of embryos with oviductal explants resulted in superior development of four-to eight-cell embryos, as indicated by the proportion that reached the blastocyst stage and by the number of cells.     

Attempts at in vitro fertilization and culture of in vitro matured oocytes in sei ( Balaenoptera borealis) and Bryde's ( B. edeni) whales

The cumulus-oocyte-complexes (COCs) recovery rates with respect to reproductive status per sei (Balaenoptera borealis) and Bryde's (B. edeni) whales were determined in Experiment 1. The number of COCs recovered ranged from 16.0 to 30.6 and from 6.7 to 26.8 per sei and Bryde's whales, respectively. The effects of COCs grades and protein supplementation in embryo culture medium on development of in vitro fertilized (IVF) embryos were evaluated in sei and Bryde's whales in Experiment 2. The COCs were classified into either Grade A (COCs with five or more layers of compact cumulus cells) or Grade B (COCs with less than five layers of compact or expanded cumulus cells) before being cultured for IVM. The cleavage (12.0 to 19.5%), 4-cell (8.0 to 12.0%) and 8-cell (4.0 to 8.0%) formation rates in sei whales did not vary significantly between embryos derived from either grade A or B oocytes and between embryos cultured in either fetal whale serum (FWS)- or bovine serum albumin (BSA)-supplemented medium. The cleavage (4.0 to 14.8%), 4-cell (0.0 to 7.5%) and 8-cell (0.0 to 2.6%) formation rates in Bryde's whales did not vary significantly between embryos derived from either grade A or B oocytes and between embryos cultured in either FWS- or BSA-supplemented medium. The grade B oocytes cultured in FWS-supplemented medium developed to morula stage (1.1%) in sei whales. In conclusion, the present study indicates that IVF in sei whales is possible to achieve cleaved embryos developing to morula stage. This is the first in vitro embryo production attempt in sei and Bryde's whales.     

Improvement of in vitro co-culture systems for bovine embryos using a low concentration of carbon dioxide and medium supplemented with beta-mercaptoethanol

Two experiments were conducted to investigate the effect of carbon dioxide (CO2) gas atmosphere and beta-mercaptoethanol on the development of bovine embryos in an in vitro co-culture system. In Experiment 1, in vitro-matured bovine oocytes were inseminated and then co-cultured with cumulus cells in culture medium (CM; 25 mM HEPES buffered TCM-199 supplemented with 5% superovulated cow serum and 0.5 mM sodium pyruvate). Oocytes matured and fertilized in 2 or 5% CO2 in air exhibited similar cleavage rates, but the proportion of embryos that developed to the blastocyst stage was higher for embryos co-cultured in 2 versus 5% CO2 in air. In Experiment two, 4- to 8-cell embryos produced under the condition of 2% CO2 in air were co-cultured with cumulus cells in CM supplemented with various levels of beta-mercaptoethanol (0, 5, 10, 50 microM). The percentage of embryos that developed to the blastocyst stage in CM with 10 microM beta-mercaptoethanol was higher (P<0.05) than that of embryos co-cultured with 0 or 50 microM beta-mercaptoethanol. These results indicate that cumulus cell co-culture in an atmosphere of 2% CO2 in air has a marked stimulatory effect on in vitro development of bovine embryos and that addition of beta-mercaptoethanol to the co-culture medium 2 d after insemination improved the in vitro development of bovine 4- to 8-cell embryos to the blastocyst stage.     

A serum-free medium for use in a cumulus cell co-culture system for bovine embryos derived from in vitro maturation and in vitro fertilization

The objective of this study was to develop a serum-free medium for the co-culture of bovine embryos that would yield a percentage of blastocysts equal to that obtained with fetal bovine serum (FBS)-supplemented medium. Cumulus cell-enclosed oocytes (CEO) matured and inseminated in vitro were cultured in a tissue culture medium (TCM)-199 or in a serum-free medium (bovine embryo culture medium; BECM) until 240 h post insemination. Replacement of 10% (v/v) FBS with either 3 mg crystallized bovine serum albumin (BSA)/ml or 3 mg fatty acid-free BSA/ml in TCM-199 had no effect (P > 0.14) on embryo development to the >or= 2-cell (51 to 60%), >or= 8-cell (24 to 33%), blastocyst (16 to 19%) and hatched-blastocyst (7 to 10%) stages at 48, 96, 192 and 240 h post insemination, respectively. Oocyte-enclosing cumulus cells in BSA-supplemented medium grew in clusters rather than in layers, as was noted in FBS-supplemented medium. When CEO were cultured in fatty acid-free BSA-supplemented media (TCM-199 and BECM), a significantly (P < 0.001) higher percentage of oocytes developed to blastocysts after culture with (22%) or without (18%) a cumulus cell monolayer than after denuding the oocytes (7%). Glucose in concentrations of 0 to 5.56 mM added for periods of 18 and 120 h post-insemination had neither a stimulatory nor a deleterious effect on preimplantation development. In conclusion, a serum-free medium supplemented with BSA can be successfully used in a cumulus cell co-culture system for bovine embryos.     

Effects of conditioned media on porcine embryos at different stages of development

The objective of our study was to determine the effect of conditioning media with homologous porcine uterine cells on the developmental rate of porcine embryos. Cell monolayers were prepared by selective dissection and digestion of sections from the uterus of prepuberal gilts that were primed with PMSG and hCG. Conditioned media were used with 2 type of embryos: 4-cell stage (Experiment 1) or blastocyst stage (Experiment 2). In Experiment 1, embryos were collected surgically by flushing the oviducts, 36 to 48 h following the first of 2 inseminations. Embryos were cultured in Whitten's medium containing 1.5% BSA as a protein source until they attained the 4-cell stage. Embryos at the 4-cell stage were cultured randomly in either Whitten's medium with 1.5% BSA or Whitten's medium with 1.5% BSA that was previously conditioned for 24 h with an endometrial epithelial cell monolayer. Embryos were cultured in 50-microl drops covered with oil in a 38.5 degrees C, 5% CO(2) in air incubator. There was no advantage to using the conditioned media with the 4-cell stage embryos. The embryos were less developed than those cultured in nonconditioned Whitten's medium (P <0.001). In Experiment 2, embryos were cultured at the blastocyst stage. They were recovered the same way as in Experiment 1 and then cultured in Whitten's medium containing 1.5% BSA until they reached the blastocyst stage. At the blastocyst stage (Day 6), embryos were randomly assigned to 1 of the 6 following treatments: Whitten's with 1.5% BSA or Whitten's plus 1.5% BSA that was previously conditioned with endometrial epithelial cell monolayer, TCM-199 containing 0.4% BSA or TCM-199 plus 0.4% BSA that was previously conditioned with endometrial epithelial cell monolayer, finally, TCM-199 containing 10% serum or TCM-199 plus 10% serum that was previously conditioned with endometrial epithelial cell monolayer. Results show that initiation of hatching was significantly enhanced by conditioning the Whitten's media.     

Increasing the rate of blastocyst formation and hatching from in vitro-produced bovine zygotes

This study was designed to identify parameters that would facilitate early selection of superior embryos, as well as to define culture conditions that could increase the proportion of embryos proceeding to the blastocyst stage. In the first experiment, the developmental potential of bovine embryos that had reached different stages of development after 60 h of culture following insemination was assessed. No 2-cell embryos underwent further cleavage. Of the 4-cell embryos (n = 188) only 12.2% progressed to the blastocyst stage, while 62.5% of 8-cell embryos (n = 480) did so (P < 0.01). In a further experiment, the effects of conditioning the culture medium (TCM 199) either with Buffalo rat liver cells (BRLC) or bovine oviductal epithelial cells (BOEC) and the effects of co-culture with either of these 2 cell types were examined. The percentage of 8-cell embryos proceeding to the morula and blastocyst stages was independent of cell type and culture system. However, BOEC-conditioned medium supported significantly lower production of blastocysts than any of the other culture methods. Only 24.1% of the former proceeded to the blastocyst stage after the full 10 d of culture, and only 3% hatched, values that were significantly lower than in the other 3 groups (P < 0.01). Among the latter, 44% progressed to the blastocyst stage in BRLC-conditioned medium while 44 and 46% reached that endpoint after co-culture with BOEC or BRL cells, respectively. The percentages that hatched among these were 28.2, 31 and 28.5%, respectively.     

Effects of hyaluronic acid on the development of 1- and 2-cell porcine embryos to the blastocyst stage in vitro

The purpose of this study was to evaluate the ability of hyaluronic acid to improve the development of 1- and 2-cell porcine embryos to the blastocyst stage in a simple medium. In Experiment 1, we confirmed the ability of Whitten's medium supplemented with 15 mg/ml BSA to support the development of porcine embryos to the blastocyst stage under our experimental conditions. Embryos collected from oviducts were cultured at 38.5 degrees C in an atmosphere of 5% CO(2) in humidified air up to 6 d. After 2 d of culture, 82 and 78% of embryos reached the 4-cell stage or beyond in TCM199 supplemented with 10% fetal calf serum (FCS) and in Whitten's medium with BSA, respectively. However, no embryo developed to the morula stage in TCM199 after 6 d of culture. On the other hand, 26 and 15% of embryos developed to the morula and the blastocyst stage in Whitten's medium, respectively. In Experiment 2, we determined whether supplementation of hyaluronic acid in Whitten's medium would improve the development of porcine embryos to the blastocyst stage. After 6 d of culture, development of the embryos to the blastocyst stage was best supported in Whitten's medium with 4 mg/ml BSA and 0.5 mg/ml hyaluronic acid (70%). The proportion of degenerated embryos was lower in the presence than in the absence of hyaluronic acid. These results indicate that the supplementation of Whitten's medium with hyaluronic acid improves the development of 1- and 2-cell porcine embryos to the blastocyst stage.     

Development of sheep preimplantation embryos in media supplemented with glucose and acetate

Two experiments were conducted to examine the effect of supplemental glucose (G; 1.5 mM) and/or acetate (A; 0.5 mM) on the development of early sheep embryos to blastocysts when cultured in vitro in glucose-free synthetic oviductal fluid (SOF) + sheep serum or bovine serum albumin (BSA). In Experiment 1, 2- to 4-cell, 8- to 16-cell and >16-cell embryos were cultured in SOF, SOF+G, SOF+A or SOF+G+A. All media were supplemented with 10% sheep serum. In addition, embryos were cultured in either microdrops under polysiloxane oil or in multiwell dishes. Overall, development to the blastocyst stage was 3%, 30% and 68% for 2- to 4-cell, 8- to 16-cell and >16-cell stages, respectively, suggesting that an 8-cell developmental block existed under our culture conditions. Glucose supplementation had little effect on embryo development, and no overall effect was observed from the addition of acetate. In Experiment 2, 8- to 16-cell embryos were cultured in SOF or SOF+G, both supplemented with BSA. Development to the blastocyst stage was 25% and 18%, respectively. The results show that the presence of glucose or acetate did little to enhance embryonic development in our incubation systems. Further work is required to evaluate fully the energy requirements for development of the early sheep embryo.     

Intracytoplasmic glutathione concentration and the role of beta-mercaptoethanol in preimplantation development of bovine embryos

In vitro-matured/in vitro-fertilized bovine oocytes were cultured on cumulus cell layers in a serum-free medium (bovine embryo culture medium; BECM) supplemented with 3 mg/ml fatty acid-free BSA. The intracytoplasmic glutathione concentration of embryos was found to change significantly (P < 0.008) during the preimplantation stages, beginning to increase at the 9- to 16-cell stage (20.7 pM/embryo) and reaching the highest (P < 0.03) level at the hatched-blastocyst stage (36.7 pM/embryo). A significantly (P < 0.06) lower concentration of glutathione was obtained at the 2- to 8-cell stage (7.1 pM/embryo) than at any other stage. When inseminated oocytes were cultured in BECM supplemented with different concentrations of beta-mercaptoethanol (2-ME) to promote glutathione synthesis, higher (P < 0.05) percentages of embryos developed to the 9- to 16-cell, morula and blastocyst stages at 96, 144 and 192 h post insemination, following the addition of 6.25 and 12.5 microM than after no supplementation with 2-ME. However, when 16-cell embryos were cultured in BECM supplemented with 6.25 and 12.5 microM of 2-ME, blastocyst formation was not significantly (P > 0.9) increased. When the combined effects of 2-ME and/or cumulus cells were compared in a 2 x 2 factorial design, there was a significant (P < 0.03) effect of 2-ME on the development of oocytes to blastocysts. The presence of cumulus cells significantly (P < 0.001) affected development after the fourth cleavage (morula compaction and blastocyst formation), but there was no significant (P > 0.11) interaction between 2-ME and cumulus cells. In conclusion, intracytoplasmic glutathione concentration of bovine embryos derived from in vitro-culture increases during preimplantation development. The glutathione synthesis promoter 2-ME exerts its embryotropic role on the development before the fourth cleavage, thus yielding an improvement in blastocyst formation.     

牛体外受精卵在两种共同培养系统中发育的研究

为了使牛体外受精卵能通过体外早期发育阻滞期,我们建立了卵丘细胞单层(A)和输卵管上皮单层(B)两种共同培养系统。A1共同培养实验是在本实验室进行的,A2和B共同培养实验均在日本岗山大学农学部动物繁殖学研究室进行,牛输卵管组织的分离使用0.76％EDTA—PBS溶液,共同培养系统均使用含10％小牛血清的TCM—199(Earle's salts)作为培养液。培养的卵泡卵母细胞体外成熟率为100％,体外受精率为99—100％。在A1共同培养实验中,越过阻滞期发育到16—细胞以上的胚胎占卵裂胚的35.7％,与A2共同培养实验中越过阻滞期的发育率(40.1％)无显著差异(P<0.05)。A1和A2共同培养实验,在卵裂基础上得到的桑椹胚和囊胚发育率分别为23.7％和27.9％。每百枚培养的卵母细胞,在A1共同培养实验中可获得桑椹胚和囊胚15.1枚,在A2共同培养实验中可获桑椹胚和囊胚的20.5枚。B共同培养实验中桑椹胚和囊胚发育率为54.1％,显著高于A1或A2共同培养实验的相应发育率(P<0.001),使用B共同培养系统每百枚培养的卵母细胞可以获得37枚桑椹胚和囊胚。     

Culture of one-cell bovine embryos in explanted mouse oviduct and bovine oviductal epithelial cells

One-cell bovine embryos fertilized in vivo were cultured in TCM-199 and bovine oviductal epithelial cells, in TCM-199, or in explanted immature mouse oviducts supported by TCM-199 to compare development to the blastocyst stage. The morphological stage of development and cell number were determined following 144 hours of culture. Of the embryos that cleaved at least once, 52.6, 30.4 and 0.0% developed to the morula/blastocyst stage after culture in oviductal epithelial cells, in TCM-199 alone, or in explanted mouse oviducts, respectively. The mean total cell number for embryos cultured in oviductal epithelial cells (24.5) was higher than for embryos cultured in TCM-199 (12.8) or in explanted mouse oviducts (5.9; P<0.05). The mean cell number of embryos cultured in TCM-199 or in explanted mouse oviducts did not differ. The explanted immature mouse oviduct supported by TCM-199 did not provide an environment adequate for development of one-cell bovine embryos to the blastocyst stage. Development of one-cell bovine embryos was best supported by co-culture with oviductal epithelial cells in TCM-199 medium.     

Oviduct Epithelial Cell Co-culture of early Porcine Embryos

One- to 16-cell porcine embryos were cultured in either Whittens medium supplemented with bovine serum albumin and fetal calf serum (WM) or in the same medium with porcine oviduct epithelial cell co-culture (WM-Poec). All stages of embryos cultured in WM-POEC had higher cell counts after 144–168 h of development than did embryos in WM. There was however, no significant difference in blastocyst formation rate of embryos cultured in WM-POEC over those cultured in WM. A high proportion of the embryos entering culture at the 1-2-cell were able to pass the 4-cell block stage in both WM and WM-POEC, 81% and 77%, respectively. In both media, most of the 1-2-cell embryos arrested their development at the compacted morula stage and failed to blastulate while embryos initiating culture at the 4-and 8-16-cell embryos formed blastocysts in culture at a rate of 80–90%.     

In vitro culture of sheep oocytes matured and fertilized in vitro

Sheep oocytes that matured and fertilized in vitro were cultured to evaluate their cleavage to the 8- to 16- cell stage and further development in five different media as follows: 1) CPMW (TCM199 + 20% ewe serum + 0.4% BSA), 2) Ham's F-10 + 10% ewe serum, 3) Brinster's pyruvate medium + 0.1% glucose (BPM-G), 4) co-culture with sheep oviduct epithelial cells in TCM199 + 10% fetal calf serum, and 5) co-culture with sheep granulosa cells in the same medium as 4. The culture duration was 4 or 7 d for 8- to 16-cell or further development. The proportions of 8- to 16-cell eggs were 1) 16% (8 49 ), 2) 25% (12 49 ), 3) 52% (58 112 ), 4) 63% (105 167 ) and 5) 45% (27 60 ). The co-culture with sheep oviduct cells resulted in a significantly (P < 0.05) higher rate of cleavage than the other media, except BPM-G. The proportion of noncompacted morula (35%, 24 68 ) was also significantly (P < 0.05) higher in the co-culture of sheep oviduct cells than the other media. The 8- to 16-cell eggs produced by BPM-G (n=38) and the co-culture with sheep oviduct cells (n=42) were transferred into the uterus of recipient ewes, but no elongated blastocysts were obtained 13 d later. On the other hand, 8 out of 55 one-cell eggs (15 to 18 h after in vitro insemination) transferred to the oviduct of recipient ewes were elongated blastocysts (24% of 34 recovered eggs). The data show that the co-culture of in vitro fertilized eggs with sheep oviduct epithelial cells could support development of 8- to 16-cell embryos or early morula, but their viability is still questionable.     

Effects of co-culture, medium components and gas phase on in vitro culture of in vitro matured and in vitro fertilized bovine embryos

To develop an in vitro culture system for bovine oocytes and early embryos, we examined the effects of co-culture of in vitro matured and in vitro fertilized embryos with trophoblastic vesicles and cumulus cells. We also studied the effects of culture medium components and oxygen gas pressure by modifying TCM-199 medium and using a gas-tight chamber. We found that co-culture with trophoblastic vesicles or cumulus cells promoted early embryos to develop beyond the eight-cell block; 17 to 19% of the initial oocytes developed to the morula stage. The effects of removing glucose and other energy sources from the medium, adding EDTA to the medium, reducing the concentration of serum, and reducing the oxygen gas pressure on the development of embryos were also examined. These modifications during the initial phase of co-culture greatly increased the rate of embryo development to the morula (36 to 38% of oocytes developed to morulae) and blastocyst stages.     

In vitro development of bovine one-cell embryos: Influence of glucose, lactate, pyruvate, amino acids and vitamins

To elucidate the effect of nutrient substrates on embryo development, in vitro fertilized bovine one-cell embryos were cultured in a medium similar to synthetic oviduct fluid (SOF) but without glucose and containing 3.3 mM lactate, 0.3 mM pyruvate and 3 mg/ml bovine serum albumin (BSA) at 39 degrees C in 5% CO(2) in air. Results indicated that addition of glucose was not only unnecessary, but it also had a deleterious effect on embryo development to the morula stage. Lactate supported embryo development up to the morula stage as well as pyruvate. Supplementation with 20 amino acids contained in basal medium Eagle's (BME) and minimum essential medium (MEM) improved development to the morula stage dramatically and increased the cell number compared with that of the controls. Addition of the vitamins from MEM to SOF had no beneficial effect. The SOF with amino acids did not increase the frequency of blastocysts 7 days after in-vitro fertilization but did increase the total number of cells compared with that of the controls. Frequency of blastocysts at Day 7 in SOF with amino acids was equivalent to that of co-culture although the total cell number was lower. These results demonstrate that a semi-chemically defined medium can successfully support the development of bovine embryos to the morula stage to a limited extent, but the medium lacks some nutrients or growth factors to fully support development through the blastocyst stage.     

Triglyceride content of bovine oocytes and early embryos

A microfluorescence technique was used to measure the triglyceride content of a minimum of two bovine oocytes or preimplantation embryos up to the hatched blastocyst stage. Embryos were produced in vitro from abattoir-derived ovaries and grown in medium containing synthetic oviductal fluid, amino acids and BSA (SOFaaBSA medium); 10% fetal calf serum was added to some of the embryos at the four-cell stage. Before maturation, the triglyceride content of oocytes was 59 +/- 1.37 ng and it decreased (P < 0.05) after maturation to 46 +/- 0.85 ng. A decrease in triglyceride content (P < 0.05) was also observed after fertilization with the formation of the two-cell embryo (34 +/- 1.80 ng). In the absence of serum, the triglyceride content remained relatively constant from the two-cell to the hatched blastocyst stage. The triglyceride content of blastocysts produced in vivo was similar (33 +/- 0.70 ng) to that of blastocysts produced in vitro in the absence of serum. In contrast, the triglyceride content of embryos grown with 10% fetal calf serum increased steadily from the 9-16-cell stage to a value in hatched blastocysts (62 +/- 1.14 ng) almost double that in serum-free conditions. These results indicate that triglyceride may act as energy source during bovine oocyte maturation and fertilization and that the presence of serum causes excessive synthesis or accumulation of triglyceride in early embryos.     

Effect of biopsy and vitrification on in vitro survival of ovine embryos at different stages of development

The objective of the present study was to assess the in vitro viability of ovine embryos at different stages of development after combining cell sampling and vitrification. Precompacted morulae, compacted morulae and blastocysts were obtained from superovulated Sarda ewes at 4, 5 or 6 d following insemination. Embryo cell biopsy was carried out in a 100-microl drop of PBS + 10% fetal calf serum (FCS) with 10 micromol nocodazole and 7.5 microg/ml cytochalasin-b by aspiration (3-5 cells). Embryos were cryopreserved at room temperature after exposure of 2 solutions for 5 min, transferred into a vitrification solution, loaded into the center of 0.25-ml straws separated by air bubbles from 2 columns of sucrose 0.5 M and plunged immediately into liquid nitrogen. In Experiment 1, the in vitro viability of manipulated or vitrified embryos after in vitro co-culture in TCM 199 medium with 10% FCS and sheep oviductal epithelial cells (SOEC) in 5% CO2 humidified atmosphere in air at 39 degrees C was significantly lower (P < 0.05 and P < 0.01, respectively) at precompacted morula (60 and 30%) and compacted morula (62 and 39%) stages than intact embryos at the same stages (87 and 88%). No differences were found at the blastocyst stage. In Experiment 2, the in vitro survival rate of precompacted morulae which were manipulated and immediately vitrified was lower (P < 0.05) than in those manipulated and, after a temporary period of culture, vitrified at blastocyst stage (21 vs 48%); while no differences were found at compacted morula and blastocyst stages. The results show that 1) the stage of development influences the subsequent in vitro viability of manipulated and vitrified ovine embryos, 2) temporary culture after manipulation and before vitrification improves the in vitro viability of embryos, and 3) the hole in the zona pellucida resulting from biopsy does not affect blastocyst survival after subsequent vitrification.     

Porcine oviductal cells support in vitro bovine embryo development

This study was designed to investigate the developmental competency of in vitro-matured and in vitro-fertilized bovine embryos co-cultured with a) medium alone, b) bovine oviductal cells (BOC), c) bovine conditioned medium (BCM), d) porcine oviductal cells (POC), and porcine conditioned medium (PCM). Follicular oocytes collected from cattle at local slaughterhouses were matured and fertilized in vitro. Epithelial cells were scraped from the luminal surface tissue of either bovine or porcine oviducts collected after ovulation, cultured in TALP + 10% heat-treated fetal calf serum, and the conditioned media were collected following a 3- to 5-d incubation period. After 18 to 22 h of sperm-ova co-incubation, the fertilized and/or cleaved ova were randomly assigned to 1 of 5 co-culture groups. The results revealed that the efficiency of medium alone in supporting embryo development from the 16- to 32-cell stage up to the blastocyst stage was significantly (P<0.01) lower than of embryos co-cultured with either bovine or porcine epithelial cells, or with conditioned media from such cells. Epithelial cell co-culture, regardless of cell source, was more effective (P<0.01) than culture with conditioned medium. Co-culture in medium containing or conditioned by porcine cells was more effective in supporting bovine embryo development than co-culture with bovine-derived cells or conditioned medium. These data support the concept that oviductal cells produce a soluble component which enhances embryo development to the blastocyst stage in vitro and that the effect is not species-specific.     

Effect of protein supplementation in potassium simplex optimization medium on preimplantation development of bovine non-transgenic and transgenic cloned embryos

The present study evaluated the effect of protein supplementation in potassium simplex optimization medium (KSOM) on bovine preimplantation embryo development. The in vitro fertilized (IVF) (Experiment 1), non-transgenic (Experiment 2) and transgenic cloned embryos (Experiment 3) were cultured for 192 h in KSOM supplemented with 0.8% BSA (KSOM-BSA), 10% FBS (KSOM-FBS) or 0.01% PVA (KSOM-PVA). Transfected cumulus cells with an expression plasmid for human alpha1-antitrypsin gene and a green fluorescent protein (GFP) marker were used to produce transgenic cloned embryos. Modified synthetic oviductal fluid (mSOF) supplemented with 0.8% BSA (mSOF-BSA) was used as a control medium. In Experiment 1, cleavage rate was significantly (P < 0.05) lower (69.1%) in IVF embryos cultured in KSOM-FBS than in KSOM-BSA (80.3%). The rate of hatching/hatched blastocyst formation was significantly (P < 0.05) lower in embryos cultured in KSOM-PVA than in KSOM-FBS (2.2% versus 10.8%). Blastocysts cultured in KSOM-FBS contained significantly (P < 0.06) higher numbers of inner cell mass cells (50.4 +/- 20.2) than those cultured in mSOF-BSA (36.9 +/- 19.2). In Experiment 2, the rate of blastocyst formation was significantly (P < 0.05) lower (20.5%) in embryos cultured in KSOM-PVA than in other culture media (33.3-38.5%). The rate of hatching/hatched blastocysts was significantly (P < 0.05) lower in KSOM-PVA (13.9%) and KSOM-FBS (17.1%) than in KSOM-BSA (30.8%) and mSOF-BSA (33.9%). The numbers of total and trophectoderm cells (104.6 +/- 32.2 and 71.7 +/- 25.5, respectively) were significantly (P < 0.05) lower in blastocysts cultured in KSOM-PVA than in KSOM-BSA (125.7 +/- 39.7 and 91.7 +/- 36.2, respectively). In Experiment 3, no significant differences in embryo development, GFP expression and blastocyst cell numbers were observed among the culture groups. In conclusion, the present study demonstrated that KSOM and mSOF supplemented with BSA were equally effective in supporting development of bovine non-transgenic and transgenic cloned embryos. Moreover, different developmental competence in response to protein supplementation of KSOM was observed between bovine non-transgenic and transgenic cloned embryos.