342 EFFECTS OF MELATONIN ON PREIMPLANTATION DEVELOPMENT OF PORCINE PARTHENOGENETIC EMBRYOS

2010 ◽  
Vol 22 (1) ◽  
pp. 327 ◽  
Author(s):  
J.-T. Kang ◽  
O.-J. Koo ◽  
D.-K. Kwon ◽  
S.-J. Park ◽  
M. Atikuzzaman ◽  
...  
Keyword(s):  
Treatment Group ◽  
Beneficial Effect ◽  
Real Time ◽  
Cell Expansion ◽  
Cumulus Cell ◽  
Cumulus Cells ◽  
Pcr Analysis ◽  
Melatonin Treatment ◽  
Parthenogenetic Embryos

In mammalian species, melatonin is a multi-functional pineal gland hormone that regulates several circadian and seasonal rhythms including reproduction. However, the melatonin study was not common as to the oocytes in the pig. Recently, we reported that exogenous melatonin has beneficial effects on nuclear and cytoplasmic maturation during porcine oocyte IVM and we also reported an existence of melatonin receptor on the cumulus cells and granulose cells (Kang JT et al. 2009 J. Pineal Res. 46(1), 22-28). In this study, as adding further experiments rather than our previous study, we investigated effect of exogeneous melatonin (10 ng mL-1) on the porcine oocytes and analyzed possible factors which can be responsible for that results. Oocytes were recovered by aspiration of slaughterhouse ovaries, and then matured in TCM-199 supplemented with EGF, insulin, pyruvate, cystine, and gonadotropin. Expression of apoptosis-related genes mRNA in oocytes cultured with melatonin were evaluated by real-time PCR (Exp 1), cumulus cell expansion on COC was assessed on the microscopes during in vitro maturation (Exp 2), and developmental effects between melatonin treatement group and non-treatment group on the in vitro culture of parthenogenetically activated oocytes was investigated (Exp 3). In results, oocytes matured with melatonin were assessed for the expression of apoptosis-related genes Bcl-xl (anti-apoptotic gene) and Bax (proapoptotic gene) by real-time quantitative PCR. Analysis of data showed that the expression of Bcl-xl was higher compared to the control while the expression of Bax was decreased relative to the control (P < 0.05). Cumulus cell expansion was evaluated under a stereomicroscope at 22 h, 44 h during IVM. Representative photomicrographs of porcine COC at the start of the IVM, after 22 h and 44 h treatment with melatonin, are shown in Figure. After 22 h of melatonin treatment, cumulus cells were visually expanded compared with non-treatment group. We analyzed significantly greater proportion of parthenogenetically activated oocytes developed to blastocyst when the IVM medium was supplemented with melatonin. Melatonin treatment in the IVM has consequently beneficial effect on the blastocyst formation rates on the development of porcine parthenogenetic embryos (15.4%) compared to non-treatment group (10.7%, P < 0.05). However, cleavage frequency was not affectedby the treatment. In conclusion, the present study demonstrated that melatonin had a beneficial effect on the development of parthenogenetically activated porcine embryos, probably through decreased apoptosis rate and increased cumulus cell expansion. This study was supported by Korean MKE, MEST (BK21 program), and Hanhwa L&C

60 EFFECTS OF AY9944 A-7 ON MEIOTIC RESUMPTION OF PORCINE OOCYTES AND CUMULUS CELL EXPANSION

2016 ◽  
Vol 28 (2) ◽  
pp. 160
Author(s):  
S. Lee ◽  
C. Khoirinaya ◽  
J.-X. Jin ◽  
G. A. Kim ◽  
B.-C. Lee
Keyword(s):  
Gene Expression ◽  
Oocyte Maturation ◽  
Cell Expansion ◽  
Cholesterol Biosynthesis ◽  
Cumulus Cell ◽  
Cumulus Cells ◽  
Mitogen Activated Protein Kinase ◽  
Control Group ◽  
Cumulus Expansion

In vitro studies on mammalian oocytes have shown that follicular fluid-meiosis activating sterol (FF-MAS) can overcome the inhibitory effect of hypoxanthine (Hx) on the resumption of meiosis. FF-MAS, an intermediate in the cholesterol biosynthesis pathway, is converted to testis meiosis–activating sterol by a sterol Δ14-reductase. AY9944 A-7, an inhibitor of Δ14-reductase and Δ7-reductase, induces accumulation of FF-MAS by inhibiting its metabolism. The aim of this study was to evaluate the effects of AY9944 A-7 on meiotic resumption of porcine oocytes, cumulus cell expansion, and gene expression related to M-phase-promoting factor (MPF), mitogen-activated protein kinase (MAPK), and oocyte maturation in oocytes and related to cumulus expansion in cumulus cells. In experiment 1, 1136 cumulus-oocyte complexes (COCs) were cultured in IVM media with 4 different concentrations (0, 10, 20, and 40 μM) of AY9944 A-7 in addition to a meiotic inhibitor (Hx, 4 mM) for 44 h. Oocytes treated with 10 and 20 μM AY9944 A-7 in the presence of Hx had significantly higher GVBD and M2 rates than the control group. However, 40 μM AY9944 A-7 significantly decreased GVBD and M2 rates and increased degeneration of oocytes compared with other groups. In experiment 2, 600 COCs were cultured in IVM media with 4 different concentrations (0, 10, 20, and 40 μM) of AY9944 A-7 in the absence of Hx for 44 h. Cumulus expansion of 40 μM AY9944 A-7 treated group was significantly decreased compared with other groups. In experiment 3, we evaluate the effects of AY9944 A-7 on gene expression, and the experiment was replicated four times. Data on gene expression were analysed using Student’s t-test. Oocytes treated with 10 μM AY9944 A-7 increased expression of genes involved in MPF (Cyclin B and Cdc2), MAPK (C-mos), and oocyte maturation (GDF9 and BMP15). Cumulus cells treated with 10 μM AY9944 A-7 decreased cumulus expansion-related genes (Has2, Tnfaip6, Ptgs2, and Ptx-3). In conclusion, our results suggest that although 10 μM AY9944 A-7 decreased cumulus expansion-related genes, there was no difference in cumulus expansion and it induced meiotic resumption of porcine oocytes with increased MPF, MAPK, and oocyte maturation-related genes. Further studies are needed to evaluate the effect of AY9944 A-7 on porcine embryo development. This study was supported by Ministry Of Trade, Industry & Energy (#10048948), Korea IPET (#114059–3), Research Institute for Veterinary Science, TS Corporation, and the BK21 plus program.

Time course of the meiotic arrest in sheep cumulus–oocyte complexes treated with roscovitine

Zygote ◽  
2015 ◽  
Vol 24 (2) ◽  
pp. 310-318 ◽  
Author(s):  
Letícia Ferrari Crocomo ◽  
Wolff Camargo Marques Filho ◽  
Camila Louise Ackermann ◽  
Daniela Martins Paschoal ◽  
Midyan Daroz Guastali ◽  
...  
Keyword(s):  
Exposure Time ◽  
Cell Expansion ◽  
Time Course ◽  
Cumulus Cell ◽  
Germinal Vesicle ◽  
Cumulus Cells ◽  
Nuclear Maturation ◽  
Maturation Medium

SummaryTemporary meiosis arrest with cyclin-dependent kinases inhibitors has been proposed in order to improve the quality of in vitro matured oocytes. In sheep, however, this phenomenon has been rarely investigated. Therefore, the present study aimed to evaluate the effect of different incubation times with roscovitine on nuclear maturation and cumulus cell expansion of sheep cumulus–oocyte complexes (COCs). For this, COCs were cultured for 0, 6, 12 or 20 h in basic maturation medium (Control) containing 75 μM roscovitine (Rosco). After, they were in vitro matured (IVM) for 18 h in the presence of luteinizing hormone (LH) and follicle-stimulating hormone (FSH). At the end of each treatment, cumulus cell expansion and nuclear maturation were assessed under a stereomicroscope and by Hoechst 33342 staining, respectively. In the Control and Rosco groups, the absence of cumulus cell expansion prevailed at 0, 6, 12 and 20 h. After IVM for 18 h, total cumulus cell expansion in the Rosco treatments was dependent on the exposure time to roscovitine. A significantly high percentage of oocytes treated with roscovitine for 6 h (87%), 12 h or 20 h (65%) were arrested at the germinal vesicle (GV) stage. In contrast, 23% GVBD, 54% metaphase I (MI) and 61% MII oocytes were observed in the Control groups at 6, 12 and 20 h, respectively. In all treatments, a significant percentage of oocytes reached MII after IVM for 18 h. Therefore, roscovitine reversibly arrested the meiosis of sheep oocytes during different culture times with the maximal efficiency of meiotic inhibition reached at 6 h. In addition, reversibility of its inhibitory action on cumulus cells was exposure-time dependent.

scholarly journals In vitro maturation of domestic cat oocytes subjected to different incubation times

2021 ◽  
Vol 10 (3) ◽  
pp. e15710313074
Author(s):  
Denilsa Pires Fernandes ◽  
Fernanda Araujo dos Santos ◽  
Luã Barbalho de Macêdo ◽  
Roberta Gonçalves Izzo ◽  
Brenna de Sousa Barbosa ◽  
...  
Keyword(s):  
Incubation Period ◽  
Cell Expansion ◽  
In Vitro Maturation ◽  
Polar Body ◽  
Cumulus Cell ◽  
Cumulus Cells ◽  
Domestic Cat ◽  
First Polar Body ◽  
The Ideal

The aim of this study was to evaluate the effect of three different incubation times on in vitro maturation of domestic cat oocytes. Thus, ovaries (n = 42) were submitted to slicing procedure and the oocytes recovered were classified; only good quality oocytes (Grade I and II) underwent in vitro maturation for three different periods (24 vs. 30 vs. 36 h) in supplemented TCM-99 medium. After, oocytes were evaluated for cumulus cell expansion and presence of the first polar body. After six replicates (7 ± 1,7 ovaries per replicate), a total of 334 viable oocytes were recovered. Differences (p <0.05) were observed regarding the percentage of oocytes presenting expansion of the cumulus cells, where higher values were observed in the group of oocytes incubated for 36 h (84.3%), when compared to 30 (73.4%) and 24 h (71.0%). Moreover, differences were also observed regarding the presence of the first polar body (24 h: 29.7%; 30 h: 58.2%; 36 h: 69.8%). We conclude that the incubation period influenced the maturation rates, indicating 36 h as the ideal period for the in vitro maturation of domestic cat oocytes in supplemented TCM-199 medium.

Effect of maturation medium on in vitro cleavage of canine oocytes fertilized with fresh and cooled homologous semen

Zygote ◽  
2007 ◽  
Vol 15 (1) ◽  
pp. 43-53 ◽  
Author(s):  
B. de Ávila Rodrigues ◽  
L. Carboneiro dos Santos ◽  
J.L. Rodrigues
Keyword(s):  
Cell Expansion ◽  
Cumulus Cell ◽  
Cumulus Cells ◽  
Final Concentration ◽  
Comparative Experiment ◽  
Cell Stage ◽  
Maturation Medium ◽  
Developmental Capacity ◽  
Fresh Semen

SUMMARYThis study evaluated the effect of three maturation media on the development of in vitro-matured and in vitro-fertilized dog oocytes. In Experiment 1 (non-comparative experiment) canine cumulus–oocyte complexes (COCs) were matured in vitro in TCM199 supplemented with estrous cow serum (10%) + gonadotropins + steroid (treatment A), TCM199 + estrous cow serum (10%) (treatment B), or TCM199 + polyvinylpyrrolidone (PVP) (4%) (treatment C). All maturation media contained a final concentration of 1 μg/ml of human somatotropin (hST). Oocytes were fertilized with fresh ejaculated sperm and development was assessed by cleavage. The objective of Experiment 2 (comparative experiment) was to compare the rates of cleavage and developmental capacity of COCs matured in vitro in same medium as in Experiment 1, and fertilized either with fresh ejaculated or with cooled extended homologous spermatozoa. In Experiments 1 and 2, oocytes fertilized with fresh semen were in vitro-matured for 48 h, while in Experiment 2 COCs fertilized with cooled semen were matured in vitro for 72 h. The results of Experiments 1 and 2 demonstrated that cleavage was not influenced by the oocyte's maturation environment. The results of Experiment 1 showed that pronucleus formation + cleavage (day 7 after IVF) was similar among treatments A, B and C (p = 0.277). Also, in Experiment 2, pronucleus formation + cleavage (day 7 after IVF) was not different for oocytes fertilized in vitro either with fresh or cooled semen and maturated in media A (p = 0.190), B (p = 0.393) or C (p = 0.687). In both experiments, the numbers of embryos that developed to the 6–8-cell stage were higher for oocytes matured in medium A and fertilized with fresh semen, when compared with numbers of oocytes matured in media B and C. Embryo development to the 6–8-cell stage of oocytes fertilized either with fresh or cooled sperm was observed in treatments A and C in Experiment 2. Cumulus cell expansion was similar among treatments in Experiment 1. In Experiment 2, cumulus cell expansion among treatments A, B and C was similar after 48 h or 72 h of IVM. In both experiments, the greatest expansion category seen was for category 2 (outer cumulus cells slightly expanded). No correlation between cumulus expansion and cleavage were observed. Polyspermy rates in oocytes matured in medium A, and fertilized with fresh sperm were not significantly different from polyspermy rates observed using media B and C, in both experiments. Our findings indicate that treatments A, B and C are similarly effective for the cleavage of dog oocytes. Furthermore, it was demonstrated that canine oocytes matured in vitro could be fertilized by homologous cooled spermatozoa and progress to cleavage.

scholarly journals Apoptosis in cumulus cells during in vitro maturation of bovine cumulus-enclosed oocytes

Reproduction ◽  
2003 ◽  
pp. 369-376 ◽  
Author(s):  
S Ikeda ◽  
H Imai ◽  
M Yamada
Keyword(s):  
Dna Fragmentation ◽  
In Vitro Maturation ◽  
Cumulus Cell ◽  
Cumulus Cells ◽  
Treated Group ◽  
Developmental Competence ◽  
Pcr Analysis ◽  
Control Group ◽  
Dependent Manner

The aim of this study was to investigate whether apoptosis occurs in cumulus cells during in vitro maturation (IVM) of bovine cumulus-enclosed oocytes (CEOs). The bovine CEOs obtained from ovaries from an abattoir were cultured for 24 h in IVM medium in the presence or absence of 10% (v/v) fetal bovine serum. The developmental competence of enclosed oocytes, as assessed by the development of the blastocyst after IVF, was significantly higher in the serum-treated group than in the control group. The morphological features of apoptosis that were analysed by orcein staining were hardly detectable in the cumulus cells at the start (0 h) of IVM, but were evident at the end (24 h) of IVM both in the control and serum-treated groups. Genomic DNA was extracted from CEOs at 0, 6, 12, 18 and 24 h of IVM and subjected to ligation-mediated PCR (LM-PCR) to detect apoptotic internucleosomal DNA fragmentation. DNA fragmentation was hardly detectable at the start of IVM, but increased in a time-dependent manner as the IVM culture proceeded. DNA fragmentation was not observed in the oocytes, indicating that fragmentation occurs in cumulus cells. The degree of fragmentation was lower in the serum-treated group compared with the control group. The LM-PCR analysis of DNA extracted from CEOs at 24 h of IVM, in which the DNA had been pretreated with Klenow enzyme or T4 DNA polymerase, revealed that the characteristic forms of the DNA ends generated during cumulus cell apoptosis were mainly 3'-overhangs and blunt ends. In conclusion, the results of the present study demonstrate that cumulus cells in bovine CEOs spontaneously undergo apoptosis during IVM. The degree of apoptosis may be correlated with the developmental competence of the enclosed oocytes.

71 MELATONIN IMPROVES PORCINE IN VITRO MATURATION VIA SONIC HEDGEHOG SIGNALLING

2017 ◽  
Vol 29 (1) ◽  
pp. 143
Author(s):  
J.-X. Jin ◽  
S. Lee ◽  
A. Taweechaipaisankul ◽  
G. A. Kim ◽  
B. C. Lee
Keyword(s):  
Embryo Development ◽  
Sonic Hedgehog ◽  
Oocyte Maturation ◽  
In Vitro Maturation ◽  
Cumulus Cell ◽  
Cumulus Cells ◽  
Melatonin Treatment ◽  
Cumulus Expansion ◽  
Hedgehog Signalling

Melatonin (N-acetyl-5-methoxytryptamine) is the hormone synthesised from the mammalian pineal gland, which has an antioxidant property and regulates physiological processes such as cellular metabolism. It is well known that melatonin affects in vitro maturation of oocytes and embryonic development in many species. However, limited information is available on the underlying beneficial effects of melatonin. Sonic Hedgehog (Shh) signalling is important for follicular development, oocyte maturation, and embryo development. To elucidate the relationship between melatonin and Shh signalling, we designed an experiment with the following three groups: (1) control, (2) melatonin, and (3) melatonin with cyclopamine (smoothened inhibitor) during porcine in vitro maturation. Porcine ovaries were collected from prepubertal gilts at a local slaughterhouse and transported to the laboratory at 28 to 32°C. The contents of follicles 3 to 6 mm in diameter were recovered by aspiration with an 18 G needle. Cumulus–oocyte complexes were pooled and cultured in TCM-199 medium for 44 h. The aim of this study was to evaluate the effects of melatonin (10−9 M) with or without cyclopamine (2 μM) on cumulus cell expansion (a total of 432 cumulus–oocyte complexes were used in 3 replicates), embryo development after parthenogenetic activation (a total of 432 oocytes were used in 4 replicates). Moreover, we detected gene expression related to cumulus expansion, oocyte maturation, and hedgehog signalling in cumulus cells and oocyte. Results indicated that melatonin treatment significantly increased cumulus expansion index (3.75 ± 0.02 v. 3.51 ± 0.03 and 3.59 ± 0.05, respectively; P < 0.05) and blastocyst formation rates (30.4 ± 2.4 v. 21.9 ± 2.2 and 20.0 ± 2.2, respectively; P < 0.05) compared with control and melatonin with cyclopamine. In addition, the expression of cumulus expansion-related genes (Ptgs1, Ptgs2, Has2, Ptx-3, and Tnfaip6) and hedgehog signalling-related genes (Shh, Pthc1, Smo, and Gli-1) in cumulus cells were up-regulated in melatonin treatment compared with control and melatonin with cyclopamine. Similarly, the expressions of oocyte maturation-related genes (GDF9 and BMP15) in porcine oocytes were up-regulated in melatonin treatment compared with control and melatonin with cyclopamine. In conclusion, Shh signalling mediated melatonin to improve porcine cumulus cell expansion, oocyte maturation, and subsequent embryo development. Further studies are needed to evaluate the effect of melatonin on protein levels of Shh signalling. Statistical analyses were performed using SPSS 22.0 (SPSS Inc., Chicago, IL, USA). All data were tested for normality and homoscedasticity and then subjected to one-way ANOVA, followed by Duncan’s multiple range test (when the variances were assumed to be equal) or Dunnet’s T3 test (when the variances were assumed to be unequal) to determine differences among experimental groups. All results are expressed as means ± SEM; P-values < 0.05 were considered to be statistically significant. This study was supported by Ministry of Trade, Industry and Energy (#10048948), Korea Institute of Planning and Evaluation for Technology in Food, Agriculture, Forestry, and Fisheries (#311011–05–4-SB010, #114059–03–2-SB010), National Research Foundation (2016M3A9B6903410), China Scholarship Council (CSC, No. 2015–3022), Research Institute for Veterinary Science, TS Corporation, and the BK21 plus program.

227. Eggs with a surprise: the 'sperm-specific' protein SPRASA is also expressed in the oocyte

2008 ◽  
Vol 20 (9) ◽  
pp. 27
Author(s):  
L. W. Chamley ◽  
A. Wagner ◽  
D. Prendergast ◽  
K. J. Woad ◽  
A. N. Shelling
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
In Silico Analysis ◽  
Human Sperm ◽  
Cumulus Cells ◽  
Reproductive Organs ◽  
Pcr Analysis ◽  
Quantitative Real Time Pcr ◽  
Bovine Oocytes

SPRASA is a newly identified protein which in silico analysis suggests is not expressed in other tissues. Antibodies reactive with SPRASA have been identified in some infertile men and an antiserum reactive with recombinant SPRASA prevented human sperm binding to hamster oocytes in vitro, indicating an important role in sperm/oocyte recognition. The aim of this study was to investigate the spatial and temporal expression of SPRASA in reproductive and other tissues. Brain, thymus, heart, spleen, kidney, liver and the reproductive organs from duplicate female and male Balb/C mice were collected at several postnatal timepoints. RNA was extracted, reversed transcribed and analysed by quantitative real time PCR for SPRASA expression. Abattoir-derived, in vitro matured, bovine oocytes were examined for SPRASA expression by fluorescent immunochemistry. To examine SPRASA binding sites on oocytes, matured bovine oocytes were exposed to biotinylated recombinant human SPRASA or biotinylated α-lactalbumin (control), then visualised by confocal microscopy using DTAF-conjugated streptavidin. We found SPRASA mRNA was expressed in the reproductive organs of both females and male mice from postnatal day 10. Fluorescent immunochemistry indicated SPRASA was expressed on the oolemmal membrane and in the few cumulus cells remaining attached to zona-intact oocytes. Control preimmune serum did not stain the oocytes or cumulus cells. Recombinant human SPRASA bound to the oolemmal membrane of both zona intact and zona free bovine oocytes. To date the expression of SPRASA has only been reported in the testes/sperm with an additional single EST identified in brain. Our quantitative real-time PCR analysis demonstrated SPRASA is also expressed in the female reproductive organs. This was confirmed by our immunoassays which show oocytes and possibly cumulus cells express SRPASA while the oolemmal membrane has the ability to bind (sperm-derived) SPRASA. That SPRASA expression is restricted sperm and oocytes confirms the likely function of this protein in reproduction.

10-gingerol induces oxidative stress through HTR1A in cumulus cells: in-vitro and in-silico studies

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Kiptiyah Kiptiyah ◽  
Widodo Widodo ◽  
Gatot Ciptadi ◽  
Aulanni’am Aulanni’Am ◽  
Mohammad A. Widodo ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Culture ◽  
Superoxide Dismutase ◽  
In Silico ◽  
Cumulus Cell ◽  
Cumulus Cells ◽  
Sod Activity ◽  
In Silico Studies ◽  
Incubation Periods

AbstractBackgroundWe investigated whether 10-gingerol is able to induce oxidative stress in cumulus cells.MethodsFor the in-vitro research, we used a cumulus cell culture in M199, containing 10-gingerol in various concentrations (0, 12, 16, and 20 µM), and detected oxidative stress through superoxide dismutase (SOD) activity and malondialdehyde (MDA) concentrations, with incubation periods of 24, 48, 72, and 96 h. The obtained results were confirmed by in-silico studies.ResultsThe in-vitro data revealed that SOD activity and MDA concentration increased with increasing incubation periods: SOD activity at 0 µM (1.39 ± 0.24i), 12 µM (16.42 ± 0.35ab), 16 µM (17.28 ± 0.55ab), 20 µM (17.81 ± 0.12a), with a contribution of 71.1%. MDA concentration at 0 µM (17.82 ± 1.39 l), 12 µM (72.99 ± 0.31c), 16 µM (79.77 ± 4.19b), 20 µM (85.07 ± 2.57a), with a contribution of 73.1%. Based on this, the in-silico data uncovered that 10˗gingerol induces oxidative stress in cumulus cells by inhibiting HTR1A functions and inactivating GSK3B and AKT˗1.Conclusions10-gingerol induces oxidative stress in cumulus cells through enhancing SOD activity and MDA concentration by inhibiting HTR1A functions and inactivating GSK3B and AKT˗1.

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.

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