Effects of different concentrations of eugenol in maturation medium on bovine oocytes, oxidative status and preimplantation embryos

2021 ◽  
Author(s):  
Lhara Ricarliany Medeiros de Oliveira ◽  
Leonardo Vitorino Costa de Aquino ◽  
Maria Valéria de Oliveira Santos ◽  
Vicente José de Figueirêdo Freitas ◽  
Luciana Medeiros Bertini ◽  
...  
Keyword(s):  
Oxidative Status ◽  
Preimplantation Embryos ◽  
Maturation Medium ◽  
Bovine Oocytes

scholarly journals Pentose phosphate pathway activity: effect on in vitro maturation and oxidative status of bovine oocytes

2014 ◽  
Vol 26 (7) ◽  
pp. 931 ◽  
Author(s):  
Cynthia Gutnisky ◽  
Gabriel C. Dalvit ◽  
Jeremy G. Thompson ◽  
Pablo D. Cetica
Keyword(s):  
Glucose Uptake ◽  
Pentose Phosphate Pathway ◽  
Lactate Production ◽  
Pentose Phosphate ◽  
Oxidative Status ◽  
Meiotic Maturation ◽  
Mitochondrial Activity ◽  
Maturation Medium ◽  
Maturation Rate ◽  
Bovine Oocytes

The relationship between pentose phosphate pathway (PPP) activity in cumulus–oocyte complexes (COCs) and oxidative and mitochondrial activity in bovine oocytes was evaluated with the aim of analysing the impact of two inhibitors (NADPH and 6-aminonicotinamide (6-AN)) and a stimulator (NADP) of the key enzymes of the PPP on the maturation rate, oxidative and mitochondrial activity and the mitochondrial distribution in oocytes. The proportion of COCs with measurable PPP activity (assessed using brilliant cresyl blue staining), glucose uptake, lactate production and meiotic maturation rate diminished when 6-AN (0.1, 1, 5 and 10 mM for 22 h) was added to the maturation medium (P < 0.05). The addition of NADPH did not modify glucose uptake or lactate production, but reduced PPP activity in COCs and meiotic maturation rates (P < 0.05). The presence of NADP (0.0125, 0.125, 1.25 and 12.5 mM for 22 h of culture) in the maturation medium had no effect on PPP activity in COCs, glucose uptake, lactate production and meiotic maturation rate. However, in the absence of gonadotropin supplementation, NADP stimulated both glucose uptake and lactate production at 12.5 mM (the highest concentration tested; P < 0.05). NADP did not modify cleavage rate, but decreased blastocyst production (P < 0.05). During IVM, oocyte oxidative and mitochondrial activity was observed to increase at 15 and 22 h maturation, which was also related to progressive mitochondrial migration. Inhibiting the PPP with 6-AN or NADPH led to reduced oxidative and mitochondrial activity compared with the respective control groups and inhibition of mitochondrial migration (P < 0.05). Stimulation of the PPP with NADP increased oxidative and mitochondrial activity at 9 h maturation (P < 0.05) and delayed mitochondrial migration. The present study shows the significance of altering PPP activity during bovine oocyte IVM, revealing that there is a link between the activity of the PPP and the oxidative status of the oocyte.

scholarly journals 153EXPRESSION OF TGF-BETA I AND TYPE I AND TYPE II OF TGF-BETA RECEPTORS IN BOVINE EMBRYOS

2004 ◽  
Vol 16 (2) ◽  
pp. 198
Author(s):  
B.K. Kim ◽  
H.J. Chung ◽  
B.C. Yang ◽  
D.H. Kim ◽  
J.H. Woo ◽  
...  
Keyword(s):  
Embryo Development ◽  
Expression Patterns ◽  
Blastocyst Stage ◽  
Preimplantation Embryos ◽  
Type I ◽  
Bovine Embryo ◽  
Type Ii ◽  
Bovine Embryos ◽  
Mrna And Protein Expression ◽  
Bovine Oocytes

Although the effects of TGFβ1, as an important factor in the mice embryo development have been reported, little information relevant to this subject is known in the bovine embryo. The objectives of this study were to investigate the presence and expression patterns of TGFβ1 and TGFβ1 receptors, types I and II, in unfertilized oocytes and fertilized bovine embryos in normal and NT embryo development. We postulated that TGFβ1 may have a beneficial effect on the preimplantation embryo and show different expression patterns at different stages of bovine embryo development. Immature bovine oocytes were aspirated from follicles of ovaries obtained from a local abattoir and they were cultured for up to 24h and fertilized in vitro. Reverse transcription-polymerase chain reaction (RT-PCR) and immunocytochemistry were used to investigate the presence of TGFβ1 and type I and type II of TGFβ1 receptors (the essential components of the TGFβ1 signaling pathway) in unfertilized oocytes and preimplantation embryos. Also, mRNA and protein expression patterns of TGFβ1 and their receptors at various stages of embryos were examined. It was found that both receptors, as well as TGFβ1, were present in the unfertilized bovine oocytes, indicating that TGFβ1 is a maternally expressed protein. Although the type I TGFβ1 receptor was present at the morulae and blastocyst stages, the type II TGFβ1 receptor was not present at both stages. It was also confirmed that the expression level of TGFβ1 was high at the 8-cell stage, and mRNA and protein expression patterns of TGFβ1 and their receptors were not coincident. Interestingly, TGFβ1 protein was not detected at blastocyst stage of embryos, whereas the mRNA expression level was high at this stage. The results of this experiment indicate that TGFβ1 protein may be needed by embryos after the blastocyst stage and may be expressed in hatched embryos for implantation. These findings support the hypothesis that there may be an interaction between the TGFβ1 and TGFβ1 receptors in the unfertilized oocytes and preimplantation embryos, and that TGFβ1 signaling may be important for the development of the oocytes and the preimplantation embryos.

PSX-B-11 Comparing effects of FGF2 and IGF1 on the development competence of parthenogenetic activated bovine oocytes maturing in vitro

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 327-328
Author(s):  
Galina Singina
Keyword(s):  
Growth Factor ◽  
Cell Number ◽  
Blastocyst Stage ◽  
Total Cell ◽  
Control Group ◽  
Total Cell Number ◽  
Developmental Potential ◽  
Maturation Medium ◽  
Bovine Oocytes

Abstract The oocyte quality acquired during in vitro maturation (IVM) are the main limitative factors affecting the embryo production. The aim of the present research was to study effects of fibroblast growth factor 2 (FGF2) and insulin-like growth factor 1 (IGF1) during IVM of bovine oocytes on their developmental potential after parthenogenetic activation. Bovine cumulus-oocyte complexes (COC; n = 1176) were cultured for 22h in either standard maturation medium (TCM-199 supplemented with 10% fetal calf serum (FCS), 0.2 mM sodium pyruvate, 10 μg/ml FSH and 10 μg/ml LH; Control) or maturation medium supplemented with different concentrations (5–160 ng/ml) of FGF2 and IGF1. After IVM, matured oocytes activated by sequential treatment with ionomycin followed by DMAP and cyclohexamide and then cultured up to the blastocyst stage. The obtained blastocysts were fixed, and the total cell number and the level of apoptosis were determined using DAPI and TUNEL staining. The data from 4 replicates (77–91 oocytes per treatment) were analyzed by ANOVA. Cleavage rates of activated oocytes did not differ between groups and ranged from 63.7 to 68.1%. The addition of 10, 20 and 40 ng/ml of FGF2 to the IVM medium led to an increase in the yield of blastocysts [from 19.6±1.8% (Control) to 35.2±3.4, 29.8±1.9 and 31.1±2.1%, respectively (P&lt;0.05)] and in the total cell number in embryos that developed to the blastocyst stage (P&lt;0.05). Meanwhile, the blastocyst yield and the total cell number in blastocysts in the IGF1-treated groups were similar to that in the control group. No effects of both growth factors on the proportion of apoptotic nuclei in blastocysts (5.3–7.1%) were observed. Thus, FGF2 (but not IGF1) are able to maintain competence for parthenogenetic development of bovine COC during their maturation invitro. Supported by RFBR (18-29-07089) and the Ministry of Science and Higher Education of Russia.

scholarly journals LÍQUIDO FOLICULAR EQÜINO NA MATURAÇÃO IN VITRO DE OÓCITOS BOVINOS

2004 ◽  
Vol 9 (1) ◽  
Author(s):  
M.G.L. PINTO ◽  
M.I.B. RUBIN ◽  
C.A.M. SILVA ◽  
T.F. HILGERT ◽  
M.F. SÁ FILHO ◽  
...  
Keyword(s):  
Follicular Fluid ◽  
In Vitro Maturation ◽  
Mineral Oil ◽  
Control Group ◽  
Sodium Pyruvate ◽  
Vitro Fertilization ◽  
Treatment Groups ◽  
Maturation Medium ◽  
Bovine Oocytes

O desenvolvimento embrionário de oócitos bovinos maturados in vitro (MIV) foi avaliado em meio suplementado com líquido folicular eqüino (Lfe). Foram distribuídos 1045 oócitos em 11 repetições formando três grupos tratamentos (T1, T2, T3) e um controle (C). O meio de maturação utilizado foi o TCM-199 acrescido de piruvato de sódio, hormônio folículo estimulante recombinante (rFSHh) e hormônio luteinizante equino (LHe). Suplementou-se esse meio com 10% de soro de égua em estro para o grupo controle e para T1, T2 e T3, o meio foi suplementado com 5, 10, e 20% de LFe, respectivamente. Os oócitos foram maturados in vitro (MIV) por 24h. A fecundação in vitro (FIV) foi realizada em meio Talp-Fert. A MIV e a FIV foram realizadas em estufa a 39ºC com 5% de CO2 em ar e umidade saturada. Os zigotos foram cultivados em meio SOFaaci, sob óleo mineral no interior de bolsas plásticas gaseificadas. As taxas de clivagem e de blastocistos foram observadas diariamente (D), e em D7, foram superiores (P0,05) às do grupo controle. Em D9, a taxa de blastocistos do T2 foi superior (P0,05). O LFe, na concentração de 10% pode ser utilizado, em substituição ao soro de égua em estro para suplementar o meio de MIV de oócitos bovinos. Equine follicular fluid on in vitro maturation of bovine oocytes Abstract Embryo development of bovine oocytes was evaluated using maturation medium supplemented with equine follicular fluid (eFF). One thousand and forty five (1045) oocytes were distributed in 11 replications forming three treatment groups (T1, T2 e T3) and one Control (C). TCM-199 added with sodium pyruvate, rFSHh and LHe was used as maturation medium. This medium was supplemented with 10% estrous mare serum for Control group, and 5, 10, and 20% eFF, respectively, for T1, T2 e T3 groups. In vitro maturation (IVM) of all groups was performed during 24h. In vitro fertilization (IVF) was performed in TALP-FERT medium. IVM and IVF were carried out in an incubator at 39ºC with 5% CO2 in air and saturated humidity. Zygotes were cultured in SOFaaci medium, under mineral oil in gasified bags. Cleavage and blastocyst rates were daily observed (D), and at D7, were higher (P0.05) for those from control group. At D9, blastocyst rate of T2 was higher (P0.05). The eFF, at a 10% concentration, can replace the use of estrous mare serum to supplement the IVM medium of bovine oocytes.

165 FETAL CALF SERUM INFLUENCES CYCLIC GMP PATHWAY, WHICH IN TURN AFFECTS THE LIPID CONTENT IN IN VITRO-MATURED BOVINE OOCYTES

2014 ◽  
Vol 26 (1) ◽  
pp. 196
Author(s):  
K. R. L. Schwarz ◽  
R. C. Botigelli ◽  
F. C. Castro ◽  
M. R. Chiaratti ◽  
C. L. V. Leal
Keyword(s):  
Lipid Content ◽  
Fetal Calf Serum ◽  
Calf Serum ◽  
Cumulus Cells ◽  
Control Group ◽  
Maturation Medium ◽  
Cgmp Pathway ◽  
Bovine Oocytes ◽  
Synthesis And Degradation

The sensitivity of IVP embryos to cryopreservation is often associated with lipid accumulation in the cytoplasm induced by the presence of fetal calf serum (FCS) during culture. Intracellular levels of cyclic (c)AMP and cGMP are involved in the regulation of lipolysis in adipocytes; high levels stimulate lipolysis whereas low levels lead to lipogenesis. Both nucleotides are present in bovine oocytes, together with the enzymes for their synthesis and degradation. The aim of this study was to analysis the effect of FCS on the cGMP pathway and the influence of cGMP on cytoplasmic lipids in bovine oocytes. In experiments 1 and 2, cumulus–oocyte complexes (COC) were cultured for 24 h in maturation medium with different proportions of FCS (2 and 10%) and a control group was matured with 0.4% BSA. After this period, transcripts for cGMP pathway were assessed by real-time PCR (GUCY1B3 and PDE5, cGMP synthesis and degradation enzymes, respectively; experiment 1) in oocytes and cumulus cells, and cGMP levels were measured in COC using commercial enzyme immunoassay kits (EIA; experiment 2). In experiments 3 and 4, COC were matured for 24 h with 0.4% BSA and different concentrations of the phosphodiesterase (PDE)5 inhibitor (0, 10–7, and 10–5 M sildenafil) to inhibit cGMP degradation and a control group was matured with 0.4% BSA. The nucleotide levels were measured in COC (experiment 3) and the oocytes were stained with Nile Red (1 μg mL–1) for evaluation of lipid content (experiment 4). Statistical analyses were performed by ANOVA followed by Tukey post hoc test using SAS software (SAS Institute Inc., Cary, NC, USA). Data for gene expression from 5 replicates and for cGMP measurements and lipid content from 3 replicates were log10-transformed into before analyses. The level of significance was 5%. The presence of FCS reduced GUCY1B3 expression in both cells and increased PDE5A in cumulus cells (P < 0.05). In experiment 2, the groups treated with 2 (0.64 fmol/COC) and 10% FCS (1.04 fmol/COC) showed decreased cGMP levels compared with control (9.46 fmol/COC; P < 0.05). In experiment 3, inhibition of PDE5A increased cGMP levels in the treated groups (36 and 56 fmol/COC for 10–7 and 10–5 M sildenafil, respectively) compared with control (9.5 fmol/COC; P < 0.05). Therefore, sildenafil showed inverse effects compared with FCS (experiment 2). In experiment 4, oocytes treated with 10–7 and 10–5 M sildenafil showed a reduced lipid content compared with controls (11.6 ± 9.4 v. 13.9 μm2 fluorescence intensity, respectively; P < 0.05). The results suggest that FCS in maturation medium affects the cGMP pathway, interfering with the transcription of genes that control its levels, which in turn results in nucleotide reduction. Inhibition of PDE5 increases cGMP levels and reduces the lipid content of oocytes, indicating that changes in this pathway caused by FCS may affect lipid metabolism of oocytes. More studies are underway to better understand this mechanism. The authors acknowledge FAPESP 2012/00170-0 for financial support.

143 EFFECT OF FSH OR EPIDERMAL-GROWTH-FACTOR-LIKE PEPTIDE SUPPLEMENTATION TO MATURATION MEDIUM ON DEVELOPMENTAL COMPETENCE OF BOVINE OOCYTES DERIVED FROM FULLY DEVELOPED FOLLICLES INDUCED BY SUPER-STIMULATION

2017 ◽  
Vol 29 (1) ◽  
pp. 180
Author(s):  
T. Yamanouchi ◽  
S. Sugimura ◽  
H. Matsuda ◽  
M. Ohtake ◽  
Y. Goto ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Formation Rate ◽  
Calf Serum ◽  
Developmental Competence ◽  
Blastocyst Formation ◽  
Maturation Medium ◽  
Epidermal Growth ◽  
Bovine Oocytes

Bovine oocytes obtained by ovum-pick-up (OPU) following follicle growth treatment (FGT) have improved quality and competence (Imai et al. 2008 Reprod. Fertil. Dev. 20, 182). However, the effect of the presence of FSH or epidermal growth factor (EGF) like peptide during in vitro maturation (IVM) on the developmental competence of FGT oocytes has not been well known. This study was undertaken to examine the developmental competence of FGT oocytes following IVM in the presence of FSH (recombinant human FSH) or EGF-like peptide (amphiregulin; Areg) and IVF. Japanese Black cows (n = 17) were used as donors. Five days after arbitrary OPU (opu group), follicles ≥8 mm in diameter were aspirated again, a controlled internal drug release (CIDR) was inserted into the vagina, and then pFSH was injected twice a day from the evening of Day 6 to the morning of Day 10 with decreasing doses (total of 20 AU; 4, 4, 3, 3, 2, 2, 1, 1 AU/day). On the evening of Day 8, PGF2α (0.5 mg of cloprostenol) was administered. On Day 11, oocytes were aspirated from follicles with ≥5 mm in diameter of the treated donors by OPU (fgt group). The cumulus-oocyte complexes (COC) were cultured in the absence (opu-cont and fgt-cont groups) or presence of 0.1 IU mL−1 FSH (opu-fsh and fgt-fsh groups) or 100 ng mL−1 Areg (opu-areg and fgt-areg groups) in IVM medium (mTCM199 containing 5 mg mL−1 BSA) for 20 to 22 h (1 COC/5 µL, total of 162–171 COC per group), and then co-cultured with 3 × 106 sperm/mL for 6 h. The presumptive zygotes were continued to culture in mCR1aa supplemented with 5% newborn calf serum for 216 h (1 zygote/5 µL) using micro-well culture dishes (Dai-Nippon-Print). When repeating this opu-fgt session in the same cow, an interval at least for 50 days was kept, and the session was performed 28 times. Statistical analysis was carried out by Mann-Whitney’s U-test (between opu and fgt groups) or Steel-Dwass test after Kruskal-Wallis test (among all groups). The number of follicles ≥5 mm increased in the fgt than opu group (17.8 v. 2.9; P < 0.01). The number of COC collected was not different between the opu and fgt groups (23.1 v. 19.6; P > 0.05). The blastocyst formation rate was higher in the fgt than opu group (36.9 v. 23.1%; P < 0.01). Within 6 groups, the blastocyst formation rate was higher in the fgt-fsh (43.3%; P < 0.01) and fgt-areg (39.5%; P < 0.05) groups than the opu-cont (16.3%) group. The rate in the fgt-fsh group was also higher than that in the opu-fsh group (43.3 v. 18.7%; P < 0.01). These results suggested that FGT improved the developmental competence of bovine oocytes, probably through improving the ability of the COC to react against FSH/Areg.

Astaxanthin counteracts the effects of heat shock on the maturation of bovine oocytes

2018 ◽  
Vol 30 (9) ◽  
pp. 1169 ◽  
Author(s):  
J. Ispada ◽  
T. A. Rodrigues ◽  
P. H. B. Risolia ◽  
R. S. Lima ◽  
D. R. Gonçalves ◽  
...  
Keyword(s):  
Heat Shock ◽  
Cumulus Cells ◽  
Blastocyst Stage ◽  
Negative Effects ◽  
Cellular Mechanisms ◽  
Sod Activity ◽  
Oocyte Competence ◽  
Maturation Medium ◽  
Bovine Oocytes

The cellular mechanisms induced by elevated temperature on oocytes are not fully understood. However, there is evidence that some of the deleterious effects of heat shock are mediated by a heat-induced increase in reactive oxygen species (ROS). In this context, carotenoid antioxidants might have a thermoprotective effect. Therefore, the objective of this study was to determine the role of astaxanthin (AST) on oocyte ROS production and on the redox profile and developmental competency of cumulus-oocyte complexes (COCs) after 14 h heat shock (41°C) during in vitro maturation (IVM). Exposure of oocytes to heat shock during IVM increased ROS and reduced the ability of the oocyte to cleave and develop to the blastocyst stage. However, 12.5 and 25 nM astaxanthin rescued these negative effects of heat shock; astaxanthin counteracted the heat shock-induced increase in ROS and restored oocyte developmental competency. There was no effect of astaxanthin on maturation medium lipid peroxidation or on glutathione peroxidase and catalase activity in oocytes and cumulus cells. However, astaxanthin stimulated superoxide dismutase (SOD) activity in heat-shocked cumulus cells. In conclusion, direct heat shock reduced oocyte competence, which was restored by astaxanthin, possibly through regulation of ROS and SOD activity in oocytes and COCs.

Expression of methylation pathway enzymes in bovine oocytes and preimplantation embryos

2010 ◽  
Vol 9999A ◽  
pp. n/a-n/a ◽  
Author(s):  
Shuntaro Ikeda ◽  
Takahiro Namekawa ◽  
Miki Sugimoto ◽  
Shin-ichi Kume
Keyword(s):  
Preimplantation Embryos ◽  
Methylation Pathway ◽  
Bovine Oocytes

Effects of the addition of glutathione during maturation on in vitro fertilisation of prepubertal goat oocytes

Zygote ◽  
2001 ◽  
Vol 9 (4) ◽  
pp. 323-330 ◽  
Author(s):  
P. Mayor ◽  
M. López-Béjar ◽  
E. Rodríguez-González ◽  
M.T. Paramio
Keyword(s):  
Preimplantation Embryos ◽  
In Vitro Fertilisation ◽  
Treatment Groups ◽  
Fertilisation Rate ◽  
Maturation Medium ◽  
Nuclear Stage ◽  
17Β Estradiol ◽  
Bovine Fetal Serum ◽  
Fresh Semen

Glutathione (γ-glutamyl-cysteinyl-glycine; GSH) is a ubiquitous intracellular free thiol that improves development of the male pronucleus at fertilisation and has also been implicated in promoting the development of preimplantation embryos. The objective of this study was to evaluate the effects of adding GSH or cysteine to the in vitro maturation medium on intracellular GSH amounts after in vitro maturation and fertilisation of prepubertal goat oocytes. Oocytes were matured in TCM199 medium supplemented with 10% bovine fetal serum, 1 mg/ml 17β-estradiol, 10 μg/ml o-FSH, 10 μg/ml LH and 50 mg/ml gentamicin. In vitro maturation medium was completed with two independent treatments: GSH at different concentrations (0, 0.25, 0.50 and 1.00 mM) and L-cysteine at different concentrations (0, 150, 300, 600 and 900 μM). After 27 h of culture at 38.5 °C in 5% CO2 in air, the nuclear stage was evaluated. Simultaneously, another sample of oocytes was frozen and the intracellular GSH level was evaluated with spectrophotometric methodology. Oocytes were inseminated with fresh semen (2-3 × 106 sperm/ml) in TALP medium supplemented with 1 mg/ml hypotaurine. Oocytes were fixed at 20 h post-insemination to evaluate the in vitro fertilisation. Oocytes matured in 1.00 mM GSH-supplemented medium exhibited higher amounts of intracellular GSH (3.23 pmol per oocyte). The percentage of normal fertilisation (17-27%) was similar for the treatment groups. In conclusion, the addition of 1.00 mM GSH to the maturation medium could be a useful method for increasing the intracellular GSH levels of prepubertal goat oocytes. However, this increase was not associated with a higher normal fertilisation rate of prepubertal goat oocytes.

Alkaline phosphatase activity in bovine oocytes and preimplantation embryos as affected by removal of the zona pellucida and culture medium constituents

2003 ◽  
Vol 15 (5) ◽  
pp. 285 ◽  
Author(s):  
J. L. Edwards ◽  
A. M. Powell ◽  
C. E. Rexroad Jr
Keyword(s):  
Alkaline Phosphatase ◽  
Phosphatase Activity ◽  
Alkaline Phosphatase Activity ◽  
Zona Pellucida ◽  
Bovine Serum ◽  
Culture Medium ◽  
Preimplantation Embryos ◽  
Perivitelline Space ◽  
Mechanical Removal ◽  
Bovine Oocytes

The aims of the present study were: (1) to characterize alkaline phosphatase (AP) activity in bovine oocytes and embryos with intact or removed zona pellucida (ZP); and (2) to evaluate the effect of culture medium constituents on AP activity. Alkaline phosphatase activity in non-matured and matured oocytes was most evident nearest the plasma membrane and perivitelline space. In more than 90% of two- to 16-cell embryos, AP activity was observed in the perivitelline space and at blastomere contacts. In blastocysts, AP activity was localized to the trophectoderm. Only after immunodissection was AP activity detected in the inner cell mass. Removal of the ZP by pronase or mechanical means reduced AP activity. Alkaline phosphatase activity was detected in evacuated ZP after mechanical removal. Specific constituents comprising the embryo culture medium altered AP activity. Alkaline phosphatase activity was reduced in eight- to 16-cell embryos and evacuated ZP cultured in CR1aa + 0.4% bovine serum albumin compared with embryos cultured in CR1aa alone or embryos co-cultured on a monolayer of Buffalo rat liver cells in the presence of 10% fetal bovine serum. The presence of AP activity at blastomere contacts and in evacuated ZP limits its usefulness as a marker for the differentiation of embryonic cells comprising the early cleavage-stage embryo.

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