Glycosaminoglycans in porcine follicular fluid promoting viability of oocytes in culture

Copper deficiency affects the developmental competence of porcine oocytes matured in vitro

The trace element Cu is required for the activity of various enzymes essential for physiological processes. In this study, we elucidated the copper transport system in porcine follicular cells and investigated the effect of Cu chelation during in vitro maturation (IVM) of porcine oocytes and subsequent embryonic development after parthenogenetic activation (PA). Cu chelation was induced by adding tetraethylenepentamine (TEPA) to the maturation media (TCM199-PVA). First, we identified the localization and relative levels of the copper transporter CTR1 in follicular cells. The level of CTR1 protein was the highest in mature cumulus cells; moreover, CTR1 was mainly localized in the cytoplasmic vesicular compartment in oocytes, whereas it was evenly distributed in the cytoplasm in cumulus cells. A total of 42 h after IVM, the TEPA-treated group showed reduced maturation rates compared to those of the control (p < 0.05). This negative effect of TEPA disappeared when it was added to the media with Cu (Cu + TEPA group). The TEPA treatment during IVM significantly increased the mRNA levels of the Has2 gene, which is related to cumulus expansion (p < 0.05). Both Cu supplementation and chelation significantly increased the reactive oxygen species (ROS) levels in porcine oocytes (p < 0.05). When we analyzed the transcript levels of folliculogenesis-related genes in Cu chelation conditions, only the expression of MAPK3 in cumulus cells significantly increased compared to that of the control. We also evaluated the subsequent embryonic development of PA embryos. TEPA-treated oocytes showed significantly decreased blastocyst formation rates compared to those of the control. The TEPA-induced toxic effect was alleviated when Cu was added with TEPA. Our findings suggest that the Cu transport system plays an important role in the porcine follicular development process and that the Cu deficiency negatively affects porcine oocyte maturation, as well as their subsequent developmental competence.

Zinc supplementation alleviates endoplasmic reticulum stress during porcine oocyte in vitro maturation by upregulating zinc transporters

Endoplasmic reticulum (ER) stress is a major contributor to embryonic development failure. Mammalian oocytes have a high risk of exposure to cellular stress during in vitro embryo production. We investigated the effects of zinc supplementation during in vitro maturation under ER stress. We evaluated cumulus expansion, embryonic development derived by parthenogenetic activation, reactive oxygen species, protein expression of X-box binding protein 1 (XBP1), and expression of genes related to ER stress. Supplementation with 1 μg/ml zinc significantly increased the nuclear maturation of oocytes, cleavage and blastocyst formation rates, and total blastocyst cell number (p < .05). Under ER stress, zinc significantly reduced protein expression of XBP1, and increased cleavage and blastocyst rates (p < .05). Concomitantly, zinc supplementation upregulated the expression of zinc transporters (SLC39A14 and SLC39A10), PTGS2, and downregulated ER stress-related genes (sXBP1, uXBP1, ATF4, and PTPN1/PTP1B), and caspase 3. These results suggest that zinc supplementation alleviates ER stress by providing essential metal-ion transporters for oocyte maturation and subsequent embryonic development.

In vitro Production of Porcine Embryos: Current Status and Possibilities – A Review

This paper presents the current possibilities, state of knowledge and prospects of in vitro production (IVP) of pig embryos, which consists of in vitro oocyte maturation, in vitro fertilization and in vitro embryo culture. In pigs, oocyte maturation is one of the most important stages in the embryo IVP process. It determines the oocyte’s fertilization ability as well as its embryonic development. Through many research studies of the proper selection of oocytes and appropriate maturation medium composition (especially the addition of various supplements), the in vitro maturation of pig oocytes has been significantly improved. Recent studies have demonstrated that modifications of the diluents and in vitro fertilization media can reduce polyspermy. Furthermore, several adjustments of the porcine culture media with the addition of some supplements have enhanced the embryo quality and developmental competence. These updates show the progress of IVP in pigs that has been achieved; however, many problems remain unsolved.

Improved quality of porcine embryos cultured with hyaluronan due to the modification of the mitochondrial membrane potential and reactive oxygen species level

Although considerable progress has been made in pig embryo culture systems, the developmental competence and quality of the produced embryos are still lower than their in vivo-derived counterparts. Because hyaluronan (HA) regulates various cellular processes and possesses antioxidant properties, this glycosaminoglycan seems to be a promising supplement in culture media. However, until now, its beneficial influence on in vitro pig embryo development has been debatable. Hence, we aimed to investigate the effect of 0.25 mg/mL, 0.5 mg/mL and 1 mg/mL concentrations of HA on the developmental potential and quality of cultured porcine embryos. We found that 1 mg/mL HA supplementation significantly increased the obtained percentages of cleaved embryos to ∼95%, morulae to ∼87% and blastocysts to ∼77%. At 0.5 mg/mL and 1 mg/mL HA concentrations, we observed a significantly improved blastocyst quality, expressed as the total number of cells per blastocyst, number of cells in the inner cell mass, number of TUNEL-positive nuclei per blastocyst, the TUNEL index and the blastocyst diameter. Because the inner mitochondrial membrane potential (ΔΨm) and reactive oxygen species (ROS) level are important for proper embryo development, for the first time, we measured these two parameters in cultured embryos at various HA concentrations and during their development up to the expanded blastocyst stage. For blastocysts cultured with 1 mg/mL HA, the ΔΨm and ROS level were ∼1.6 and 2.7 times lower, respectively, than those of the control blastocysts. Both ΔΨm and the ROS level were increased in parallel during in vitro embryo development with and without HA, but this increase was less pronounced in the presence of HA. Hence, our quantitative data unequivocally show that supplementation of NCSU-23 culture medium with 1 mg/mL HA improves the developmental potential and quality of pig embryos. This effect results from a significant decrease in the ROS level induced by the HA-dependent ΔΨm reduction.

Syndecan 1 represses cell growth and FSH responsiveness in human granulosa cells

Albeit devoid of intrinsic catalytic activity, the transmembrane heparan sulphate proteoglycan syndecan 1 plays critical roles in cellular processes such as extracellular matrix crosstalk, cytoskeletal organization, cell spreading, proliferation and differentiation. During the ovarian cycle, the expression of syndecan 1 in granulosa cells shows cyclic variation suggesting that it might fulfil specific roles in follicle development. To investigate its physiological roles on granulosa cells, syndecan 1 was overexpressed in human granulosa cell line KGN which retains features of granulosa cells from small antral follicle such as estradiol (E2) synthesis and low expression of functional FSH receptor (FSHR). We demonstrated that overexpression of syndecan 1 in immature granulosa cells (KGN-SDC1) induces a profound alteration in their intrinsic characteristics including enhanced spreading and attachment, both associated with a reduced growth rate. Flow cytometry analysis revealed that syndecan 1 overexpression increases the percentage of KGN cells in quiescent phase. This partial cell cycle exit is concordant with downregulated levels of CCND1 and CDK4 and upregulated expression of CDK inhibitor CDKN1A. In parallel both unstimulated and FSH-induced E2 synthesis are reduced in KGN-SDC1 through both repression of CYP19A1 and FSHR mRNA associated with decreased levels of potential regulators NR5A1 and ESR2. Additionally, we provide evidence that transient cAMP accumulation reduction in cells overexpressing syndecan 1 is accompanied by an increase in cAMP-hydrolysing PDE activity. Our results demonstrated that syndecan 1 might regulate differentiation of granulosa cells and follicular development by means of various mechanisms involving morphological changes, control of signalling pathways and alterations in gene expressions.

Free French abstract: A French translation of this abstract is freely available at http://www.reproduction-online.org/content/153/6/797/suppl/DC2

Intraovarian control of selective follicular growth and induction of oocyte maturation in mammals

In newborn mammals, most of the germ cell population rests in a pool of quiescent small follicles in the ovaries. Regularly throughout adulthood, a small percentage of these oocytes and follicles grows to a certain stage of development and then either degenerates or matures and ovulates. This entire process is under both exogenous and endogenous control. Recent work, including my laboratory's, has clarified that cytokines and glycosaminoglycans are involved as exogenous and endogenous factors in ovarian follicular development, atresia, and maturation in mammals. The present article describes our contribution regarding the cytokines and ovarian glycosaminoglycans that act as intraovarian regulators of follicular development and oogenesis, including oocyte maturation, in mammals.

Glycomic analyses of ovarian follicles during development and atresia

To examine the detailed composition of glycosaminoglycans during bovine ovarian follicular development and atresia, the specialized stromal theca layers were separated from the stratified epithelial granulosa cells of healthy (n = 6) and atretic (n = 6) follicles in each of three size ranges: small (3–5 mm), medium (6-9 mm) and large (10 mm or more) (n = 29 animals). Fluorophore-assisted carbohydrate electrophoresis analyses (on a per cell basis) and immunohistochemistry (n = 14) were undertaken. We identified the major disaccharides in thecal layers and the membrana granulosa as chondroitin sulfate-derived ∆uronic acid with 4-sulfated N-acetylgalactosamine and ∆uronic acid with 6-sulfated N-acetylgalactosamine and the heparan sulfate-derived Δuronic acid with N-acetlyglucosamine, with elevated levels in the thecal layers. Increasing follicle size and atresia was associated with increased levels of some disaccharides. We concluded that versican contains 4-sulfated N-acetylgalactosamine and it is the predominant 4-sulfated N-acetylgalactosamine proteoglycan in antral follicles. At least one other non- or 6-sulfated N-acetylgalactosamine proteoglycan(s), which is not decorin or an inter-α-trypsin inhibitor family member, is present in bovine antral follicles and associated with hitherto unknown groups of cells around some larger blood vessels. These areas stained positively for chondroitin/dermatan sulfate epitopes [antibodies 7D4, 3C5, and 4C3], similar to stem cell niches observed in other tissues. The sulfation pattern of heparan sulfate glycosaminoglycans appears uniform across follicles of different sizes and in healthy and atretic follicles. The heparan sulfate products detected in the follicles are likely to be associated with perlecan, collagen XVIII or betaglycan.

Association of cumulus–oocyte complexes with the intrafollicular levels of a blood proten inBubalus bubalis

The protein pattern of the follicular fluid (FF) and the ultrastructure of the inner cumulus–oocyte complex (COC) has been analysed in single antral follicles (n= 146) of buffaloB. Bubalisovaries. The protein population of FF was fractionated by SDS-PAGE; the resulting pattern was Coomassie stained and processed for densitometry. Comparartive analysis of sera and autologous FFs showed a marked difference in the level (measured as the percentage of total proteins) of one 21 kDa polypeptide band, called ‘L’. Concentration of L, which was mainly higher in the serum (2.05 ± 1.5%) than in the surrounding FF(0.98 ± 0.94%), fluctuated widely in fluids from the in the same ovary. On gel filtration of FF and SDS-PAGE of ther factions collected, the L polypeptide was found and eluted together with a 36 kDa polypeptide, called ‘H’, with an exclusion volume lower than that of albumin. The levels of both polypeptides in the eluted fractions were measured by gel densitometry and the same ratio H/L was found (2:1). These data suggest that H and L are subunits of a complex high-molecular-weight protein. The presence of L levels in male sera comparable to those detected in females indicates that this putative protein does not originate in the ovary but is transported from the blood. Moreover, a correlation between the increase in the percentage of Lf (calculated as %L in FF/%L in serum) and atresia was observed. COCs (n= 86) obtained during the collection of the single FF samples were processed for transmission electron microscopy. The ultrastructure of each COC was compared with the SDS-PAGE data of the associated FF. Healthy COCs were found to be related to very low levels of Lf (between 0 and 14% of those measured in serum). COCs with an early atretic ultrastructure undetectable at the dissection microscope, were associated with FFs having Lf levels between 24% and 60%; advanced atresia was associated with Lf values up to 70%. Finally, the acrosome reaction of buffalo precapacitated spermatozoain vitrowas monitored by adding one volume of FF with high (FF +; Lf = 80%) or undetectable (FF - ) values of Lf to the sperm suspension. It was found that 96.2% of spermatozoa treated with FF - showed a normal acrosome reaction, without any change in their motility pattern; spermatozoa treated with FF +, in contrast, exhibited poor motility, and only 66.4% of them underwent the acrosome reaction. The ionophore A23187, in a control experiment, resulted in lower percentages of acrosome reactions (38%). In conclusion, our results suggest that enhanced influx of L from serum into the follicle antrum causes an increase in the polypeptide level in FF. This might be due to a loss of selectivity in the blood-follicle barrier of early atretic follicles. The use of the L polypeptide as a biochemical marker for identifying the earlier stage of follicular atresia is proposed.

Expression of hyaluronan synthase-3 in porcine oviducal epithelium during oestrus

Hyaluronan (HA) has been related to fertilization and embryo development in the pig. Furthermore, HA is present in pig oviduct fluid and the lining epithelium, particularly of the pre-ovulatory sperm reservoir. Because the mechanisms that regulate HA synthesis have not yet been clarified, semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) was conducted to assess the expression of mRNAs of two HA-synthesizing enzymes (has2 and has3) in the oviduct epithelium (uterotubal junction, isthmus, ampullary-isthmic junction and ampulla segments) of non-inseminated (control) and inseminated (treatment) sows at pre-, peri- and post-ovulatory oestrus. Only has3 mRNA was detected; it was present in all tubal segments of both control and treatment samples. The level of has3 expression did not vary significantly between non-inseminated and inseminated specimens, but there was a tendency (NS) for increased mean values during the peri- and post-ovulatory stages compared with pre-ovulation. It is concluded that has3 is expressed by the porcine endosalpinx epithelium and the levels of expression do not vary during the critical periods of sperm transport and fertilization, despite fluctuating levels of HA in the tubal fluid at corresponding periods.

Embryotropic effect of glycosaminoglycans and receptors in development of porcine pre-implantation embryos

The present study investigated the expression of receptors for glycosaminoglycans (GAGs) and the effect of GAGs supplementation on development of porcine IVF embryos. Total RNA was prepared from oocytes, 2-, 4- and 8-cell embryos, morulae and blastocysts. The expression of hyaluronic acid receptor (CD44) and heparin (HP) interacting protein (HIP) was determined using RT-PCR and Southern blot analysis. The CD44 and HIP mRNA were detected from in vitro matured oocytes and all stages of pre-implantation embryos. The IVF embryos were cultured in modified NCSU-23 medium supplemented with various concentrations (0, 0.1, 0.5 or 1.0 mg/mL) of hyaluronic acid (HA) or heparin. Supplementing with 0.5 mg/mL HA significantly increased total cell number compared to other experimental groups, due to increase in trophectoderm cells. Supplementing with 1.0 mg/mL, HP significantly increased blastocyst formation rate compared to the control group. Supplementing media, in which IVF embryos were cultured with 0.5 mg/mL HA + 1.0 mg/mL HP, significantly increased blastocyst formation rate compared to the control group. In conclusion, the present study demonstrated the expression of HA and HP receptors and the embryotrophic effect of HA or HP on porcine IVF embryos.

Cumulus-oocyte complex interactions during oocyte maturation

In most mammals, the oocyte in the Graafian follicle is surrounded by tightly packed layers of cumulus cells, forming the cumulus-oocyte complex. During the preovulatory period, cumulus cells change from a compact cell mass into a dispersed structure of cells for the synthesis and deposition of a mucoid intercellular matrix, a process referred to as cumulus expansion. Cumulus expansion is thought to influence a variety of fundamental developmental changes during oocyte maturation. Volumetric expansion of the cumulus-oocyte complex correlates, at least in pig, with the outcome of oocyte maturation, fertilization, and embryo development. Therefore, detailed functional studies of cumulus expansion seem to be required to elucidate the mechanism of oocyte maturation. We summarize the current knowledge about (1) morphological changes of cumulus-oocyte complexes during oocyte maturation, (2) follicle factors inducing cumulus expansion, (3) the role of cumulus expansion in oocyte maturation, (4) cytoplasmic regulators of oocyte maturation, and (5) possible roles of cumulus expansion.

The hyaluronic acid receptor (CD44) is expressed in bovine oocytes and early stage embryos

Hyaluronic acid (HA) is a high molecular weight polysaccharide found in the extracellular matrix of most animal tissues, that exerts a profound influence on cell behavior. HA is one of the most abundant glycosaminoglycans (GAGs) in the uterine, oviductal and follicular fluids in mouse, pig, human and cattle. CD44, the principal cell membrane receptor for HA, is expressed from the 1- to 8-cell stage in human embryos, during post-implantation mouse embryogenesis and on the surface of differentiated embryonic stem cells. In the present study, we have analyzed by immunofluorescence, whether CD44 is present in bovine oocytes, fertilized oocytes and early stage embryos. Bovine cumulus-oocyte complexes (COCs) were aspirated from follicles (2-5mm) and were selected for IVM and incubated for 24h. Oocytes showing an expanded cumulus (generally 90-95%) were used for IVF. Fertilized oocytes were separated for immunofluorescence assay after 16h of sperm incubation in order to fix the eggs at the pronuclear stage. The embryos were cultured for 8 days and the different stages of development for immunofluorescence assay were separated every 24h of culture. The CD44 receptor was detected at every observation time examined. Fluorescence-tagged HA for the internalization assay was prepared by mixing fluorescein amine, Isomer I and 1mg of HA from umbilical cord. Fluorescence-tagged HA was internalized in 2-, 4-, 8- and 16-cell-stage embryos, morulae and blastocysts. CD44 is expressed on the surface and in the cytoplasm of bovine oocytes and embryos in different stages of development.

The suppression of fragmentation by stabilization of actin filament in porcine enucleated oocytes

A thorough understanding of the mechanism underlying fragmentation would contribute to the improvement of the developmental ability of reconstructed embryos after nuclear transfer. We conducted the present study to elucidate the influence of the nuclear transfer method on fragmentation of enucleated oocytes and the relationship between change in actin filament distribution and fragmentation. In Experiment 1, we examined activation rates of in vitro matured oocytes. These were 12.9% in maturation alone, 75.7% in electrical stimulation, and 57.9% in ethanol/cycloheximide treatment. In Experiment 2, we observed a higher rate of fragmentation (P < 0.05) in cultured oocytes that had been enucleated and electrically stimulated than in oocytes subjected to the other treatments (maturation alone, enucleation alone and enucleation plus ethanol/cycloheximide activation). In Experiment 3, we stained enucleated and electrically stimulated oocytes with rhodamine/phalloidin dye to show discontinuous distributions in the ooplasm of treated oocytes; oocytes in the other treatment groups showed homogenous distributions of actin filaments (AFs). In Experiment 4, we added cytochalasin B, an inhibitor of AF polymerization, to the culture medium, which prevented fragmentation of enucleated plus electrically stimulated oocytes (cytochalasin B, [+] 0.0%, [-] 60.7% at 24 h after treatment, P < 0.05). In Experiment 5, we investigated the relationship between fragmentation and alteration in AF distribution in enucleated plus electrically stimulated oocytes. At 0 h of culture, enucleated plus electrically stimulated oocytes showed discontinuous distributions of AFs, while nontreated oocytes showed homogenous AF distributions. At 24 and 48 h of culture, fragmentation proceeded in enucleated plus electrically stimulated oocytes and the discontinuous AF distribution diminished with time. In Experiment 6, we added hyaluronic acid (HA) to the culture medium, which suppressed fragmentation of enucleated plus electrically stimulated oocytes (HA, [+] 28.5%, [-] 66.4% at 24 h after treatment, P < 0.05). The results suggest that electrical stimulation induces a change in the AF distribution of oocytes, resulting in fragmentation, and that the addition of HA to the culture media is effective for the suppression of fragmentation.

Expression of hyaluronan synthases and CD44 messenger RNAs in porcine cumulus-oocyte complexes during in vitro maturation

The transient synthesis and accumulation of hyaluronan (HA), an extracellular matrix component of cumulus cells, brings about expansion of cumulus-oocyte complexes (COCs) in preovulatory mammalian follicles. In this study, we investigated the mRNA expressions of hyaluronan synthase 2 (has2), hyaluronan synthase 3 (has3), and CD44, as well as the responsiveness to eCG and porcine follicular fluid (pFF) of these genes, in porcine COCs, oocytectomized complexes (OXCs), and oocytes during in vitro maturation. Immunolocalization of CD44 was also analyzed in COCs. After 12 h of culture, the area of cumulus expansion in medium 199 supplemented with both 10 IU/ml eCG and 10% (v/v) pFF was significantly greater than that in the medium supplemented with eCG or pFF. Oocytectomy reduced the expansion area in the group supplemented with eCG. In reverse transcription-polymerase chain reaction analysis, all transcripts were identified in COCs, but has3 transcript was not found in OXCs. Only has3 mRNA was detectable in oocytes, indicating that cumulus cells express has2 and CD44 mRNAs, and oocytes express has3 mRNA. The expression levels of has2 and CD44 mRNAs in COCs and OXCs increased in the presence of eCG and pFF after 24 h of culture, suggesting that these genes have a positive dependency on eCG and pFF. In contrast, the high level of has3 mRNA was detected in COCs cultured in the medium alone. Oocytectomy slightly reduced the expression level of has2 mRNA. On immunostaining for CD44, CD44 was expressed apparently in COCs cultured with eCG and pFF for 24 h. The positive staining was distributed on cytoplasm along the perimembrane of cumulus cells and at the junctions between cumulus cells and oocytes. CD44 was also localized on cytoplasm of some oocytes. These results indicate that 1) porcine oocytes promote eCG-dependent cumulus expansion and the expression of has2 mRNA in cumulus cells, but these are not essential for expansion of cumulus cells and the expression of has2 mRNA; 2) HAS2 is involved in HA synthesis during cumulus expansion, and eCG and pFF up-regulate its expression; 3) the expression profile of the has3 mRNA that is transcribed in oocytes is different from those of has2 and CD44 mRNA; and 4) CD44 may participate in the interaction between cumulus cells and oocytes.

In vitro production of embryos in swine

In recent years, progress has been achieved in the production of pig embryos through IVM and IVF techniques. Cytoplasmic maturation of oocytes has been improved by modifications to IVM procedures. However, the historical problem of polyspermic penetration still remains a major issue to be solved. Recent studies indicate that the type of IVF medium and certain modifications to that medium can reduce polyspermy. Efforts should be directed to increase the developmental competence and quality of embryos. At present, many embryo culture (EC) media are available that can overcome the historical 4-cell block and support development of early in vivo derived embryos to the blastocyst stage. In contrast, blastocyst development of in vitro produced embryos in these culture media varies significantly. Furthermore, morphology and cell numbers in in vitro produced blastocysts are inferior to their in vivo counterparts. However, several modifications to EC techniques have improved embryo quality and developmental competence. Testing embryo viability through surgical transfer to recipient animals has resulted in acceptable pregnancy rates with moderate litter sizes. Although reliable in vitro systems are available for the generation of pig embryos, the problem of polyspermy and poor embryo development hamper their large-scale implementation. Further research efforts should be directed to improve oocyte/embryo quality and the methods to minimize polyspermy through development of novel IVM, IVF, and EC techniques.

Identification and immunolocalization of decorin, versican, perlecan, nidogen, and chondroitin sulfate proteoglycans in bovine small-antral ovarian follicles

Proteoglycans (PGs) consist of a core protein and attached glycosaminoglycans (GAGs) and have diverse roles in cell and tissue biology. In follicles PGs have been detected only in follicular fluid and in cultured granulosa cells, and the composition of their GAGs has been determined. To identify PGs in whole ovarian follicles, not just in follicular fluid and granulosa cells, small (1-3-mm) bovine follicles were harvested. A proportion of these was incubated with (35)SO(4) for 24 h to incorporate radiolabel into the GAGs. The freshly harvested and cultured follicles were sequentially extracted with 6 M urea buffer, the same buffer with 0.1% Triton X-100 and then with 0.1 M NaOH. Proteoglycans were subjected to ion-exchange and size-exclusion chromatography. The GAGs were analyzed by chemical and enzymic digestion, and on the basis of their composition, we chose a list of known PGs to measure by ELISA analyses. Versican, perlecan, decorin, but not aggrecan or biglycan, were identified. These, excluding decorin for technical reasons, as well as a basal lamina glycoprotein, nidogen/entactin, were immunolocalized. Versican was localized to the thecal layers, including externa and the interna particularly in an area adjacent to the follicular basal lamina. Perlecan and nidogen were localized to the follicular basal lamina of antral follicles, both healthy and atretic, but not to that of preantral follicles. Both were localized to subendothelial basal laminas, but the former was not readily detected in arteriole smooth muscle layers. This study has confirmed the presence of versican and perlecan, but not the latter as a component of follicular fluid, and identified decorin and nidogen in ovarian antral follicles.

Effect of hyaluronic acid on development of in vitro produced bovine embryos

The present study was carried out to evaluate the effect of hyaluronic acid (HA) added to the culture medium on bovine embryo development to the blastocyst stage as well as embryo quality and viability after freezing and thawing. In vitro matured and fertilized (IVM/IVF) bovine oocytes from slaughterhouse ovaries were cultured for 8 d in SOFm supplemented with 4 mg/mL fatty acid-free BSA, either in the absence or presence of 1 or 0.5 mg/mL HA. There was a significant increase in blastocyst yield in the presence of 1 mg/mL HA (P < 0.01), whereas 0.5 mg/mL HA was ineffective. Cleavage rate and mean number of days to blastocyst formation were unaffected by HA at any concentration. At 1 mg/mL, HA did not affect either post-freeze survival of Grade 1 and 2 blastocysts or the number of nuclei per blastocyst. Supplementation with HA at 1 mg/mL also significantly enhanced embryo development up to the blastocyst stage (P < 0.05) in a chemically-defined culture medium without a protein source. It is concluded that supplementation of both semi-defined and defined culture media with 1 mg/mL HA improves the development of IVM/IVF bovine embryos to the blastocyst stage, without affecting embryo quality and post-freeze survival. These results open the possibility of including HA in culture media in order to increase the efficiency of in vitro blastocyst production from in vitro-matured bovine oocytes.

Developmental capacity of bovine oocytes matured in two kinds of follicular fluid and fertilized in vitro

This study was conducted to assess the ability of the follicular fluid derived from large and small follicles to support the in vitro oocyte maturation and subsequent fertilization and developmental capacity. Oocytes were cultured in bovine follicular fluid aspirated from small (SFF; 2-5 mm in diameter), large (LFF; 10 to 20 mm in diameter) follicles and TCM199 as a control under 5% CO2 in air. All maturation media were supplemented with 1 IU ml-1 pregnant mare serum gonadotropin. After 24 h culture, oocytes were fertilized in vitro with frozen-thawed and heparin-treated (10 micrograms ml-1, 15 min) bull spermatozoa and cultured in TCM199 with bovine oviductal epithelial cells (BOEC) for 7 days. Maturation of bovine oocytes cultured in LFF was inhibited and the low of male pronucleus formation was observed when compared with that of SFF (maturation rate: 69 vs. 78%; P < 0.05; male pronucleus formation rate: 58 vs. 80%; P < 0.05). Developmental capacity of bovine oocytes cultured in SFF was significantly (P < 0.05) higher than that of LFF (15 vs. 5%), but significantly (P < 0.05) lower than that of the control. There were no differences in the number of nuclei per blastocyst obtained after each treatment. These results indicate that the inhibitory action of follicular fluid on in vitro maturation, male pronucleus formation and developmental capacity of bovine oocytes is dependent on the developmental stage of the follicles from which fluid was obtained.

In vitro maturation of porcine oocytes in follicular fluid with subsequent effects on fertilization and embyo yield in vitro

The objective of the present study was to test the ability of porcine follicular fluid (pFF) to improve maturation of porcine cumulus-oocyte-complexes (COC) in vitro and to observe subsequent effects on fertilization and development to late morula/blastocyst stages under in vitro conditions. The COC were incubated in Tissue Culture Medium (TCM) 199, supplemented with 1% fetal calf serum (FCS), 10% pFF collected from immature follicles (2 to 5 mm), with or without addition of 1microg/ml FSH. Control groups were matured in TCM 199 with or without FSH. Follicular aspirates were centrifuged (1700 x g, 5min.) and the supematants were stored at -20 degrees in 1.5-ml Eppendorff cups until used. On 7 experimental days a total of 3849 immature COC was aspirated from follicles ranging from 2 to 5 mm in diameter. A total of 1117 COC was selected for the experiments, and 239 COC were fixed and stained with 1.5% aceto-orcein after 48 h of in vitro maturation at 39 degrees C with 5% CO(2) in humidified air. Germinal vesicle breakdown (GVBD; 91.7%) and development to metaphase II (60.4%) were superior (P <or= 0.05) when 10% pFF and 1microg/ml FSH were present in the maturation medium. Another 878 COC were mechanically denuded and used for in vitro fertilization (IVF). Eighteen hours after IVF, 561 oocytes were fixed and stained with aceto orcein. No diffeences were found among groups at this time point. Another 317 embryos were continuously cultured to morula and blastocyst stages in medium NCSU 23. Cleavage rates differed significantly (P <or= 0.05) 48 h after IVF, and were superior (52.5% vs 32.5% vs 30.7%) when oocytes were matured in maturation medium supplemented with pFF and FSH as compared with maturation rates in TCM 199 without pFF and/or FSH. Once the embryos had cleaved, no further differences were observed in the development to morula and blastocyst stages. These data indicate that GVBD and nuclear matuation to metaphase II are enhanced by a combination of pFF and FSH and that cytoplasmatic maturation is more complete and better synchronized as indicated by the increased cleavage rates.

Follicular development, oocyte viability and recovery in relation to follicular steroids, prolactin and glycosaminoglycans throughout the estrous period in superovulated heifers with a normal LH surge, no detectable LH surge, and progestin inhibition of LH surge

Estrous cycles of heifers (n = 137) were synchronized with prostaglandin (PGF2 alpha) and follicular development stimulated with follicle stimulating hormone. Twenty-eight animals were administered Norgestomet implants 12 hr prior to the initial PGF2 alpha injection to suppress the LH surge that initiates ovulation. Animals were ovariectomized every 12 hr after the initial PGF2 alpha (7-9/time, 12-108 hr and at 192 and 240 hr post PGF2 alpha) and divided into three treatment groups to consist of: 1) animals exhibiting a normal luteinizing hormone (LH) surge (n = 86), 2) animals in which no LH surge was detected (n = 23), and 3) suppression of the LH surge via Norgestomet implants (72-108 hr, n = 28). Follicular diameter was measured and follicular fluid was collected for analysis of prolactin, estradiol, progesterone and glycosaminoglycan concentrations. Progesterone concentrations were increased in animals exhibiting an LH surge as compared to animals in which no LH surge was detected; primarily in large follicles (> 8 mm diameter) after the LH surge. Animals not exhibiting an LH surge also had increased follicular progesterone concentrations compared to Norgestomet-implanted animals (242.3 +/- 36.3 vs 86.7 +/- 6.4 ng/ml, respectively, P < .01), indicating some LH stimulation. Follicular estradiol in animals exhibiting an LH surge increased up to the time of LH surge detection and then declined whereas animals with no LH surge detected had follicular estradiol concentrations that declined after the PGF2 alpha injection. No differences were noted between those that did not exhibit an LH surge or in which the LH surge was suppressed with Norgestomet in relation to follicular estradiol concentrations. Follicular estradiol concentrations increased with follicular size in all treatment groups (P < .01). Follicular concentrations of prolactin were increased in small follicles (P < .05; < or = 4 mm diameter) and follicular prolactin increased from 12 to 36 hr post PGF2 alpha injection, then declined after the LH surge. Follicular glycosaminoglycan concentrations decreased with increases in follicular size (P < .01) and were higher in animals that did not exhibit an LH surge (P < .01). No differences in follicular glycosaminoglycans were noted between Norgestomet-implanted animals and those not exhibiting an LH surge. In the animals representing days 4 and 6 of the subsequent estrous cycle (192 and 240 hr post PGF2 alpha), numbers of small-sized follicles were increased. Follicular progesterone and estradiol concentrations were related to atretic large follicles unovulated from the prior estrus and a new wave of growth in small and medium follicles.(ABSTRACT TRUNCATED AT 400 WORDS)

Cumulus and oocyte maturation and in vitro and in vivo fertilization of oocytes in relation to follicular steroids, prolactin, and glycosaminoglycans throughout the estrous period in superovulated heifers with a normal LH surge, no detectable LH surge, and progestin inhibition of LH surge

Crossbred heifers (n = 103) were synchronized to estrus with prostaglandin (PGF2 alpha) and superovulated with follicle stimulating hormone (FSH-P). Animals were ovariectomized every 12 hr after the PGF2 alpha injection (n = 7 to 9/time) up to 108 hr to monitor the follicular, hormonal, and oocyte changes associated with follicular development and ovulation. Twenty-eight animals were implanted with Norgestomet implants 12 hr before PGF2 alpha and ovariectomized at 72, 84, 96, and 108 hr post PGF2 alpha injection to monitor effects of progesterone and suppression of the luteinizing hormone (LH) surge on oocyte maturation and quality. Follicular fluid was collected and analyzed for progesterone, estradiol, prolactin, and glycosaminoglycan content in conjunction with cumulus maturation and nuclear stage of oocyte maturation. Analysis of in vivo matured oocytes by in vitro fertilization was carried out at 60, 72, 84, and 96 hr post PGF2 alpha and in vitro matured oocytes at 12 to 108 hr post PGF2 alpha. No developmental changes in cumulus cells surrounding the oocyte of small follicles was noted (< or = 4 mm dia) indicating a static population. Medium (> 4 < or = 8 mm) and large size (> 8 mm) follicles developed to the corona radiata and loose cumulus stages in animals in which an LH surge was detected but cumulus status remained primarily in the tight cumulus stage for animals without an LH surge. The estradiol-to-progesterone ratio for tight cumulus (TC), corona radiata (CR), and loose cumulus (LC) stages was 1.8 +/- .1, 1.0 +/- .1, and .4 +/- .2, respectively (P < .01). Nuclear maturation of oocytes in small follicles from animals without a detectable LH surge seem to indicate early maturation (48 to 72 hr post PGF2 alpha) in conjunction with a high percent of degenerate oocytes not seen in animals exhibiting an LH surge. Oocytes from medium size follicles matured to germinal vesicle breakdown (GVBD) and early meiosis (metaphase I; MI) stages of development in all treatments. Most oocytes were degenerate in Norgestomet-implanted animals. Oocytes from large follicles (> 8 mm dia) from animals exhibiting an LH surge were in MI and metaphase II (MII) stages (48 to 84 hr post PGF2 alpha) in preparation of ovulation whereas oocytes from animals not exhibiting an LH surge had oocytes that early matured to MII (48 to 72 hr post PGF2 alpha), later regressing to degenerate oocytes (84 to 108 hr). Follicular progesterone, estradiol, and prolactin increased with oocyte maturation, particularly in medium and large follicles.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

Environment and medium volume influence in vitro fertilisation of pig oocytes

Oviductal oocytes (n = 795) were obtained from ovulation-induced prepubertal gilts. In the first experiment, different parameters related to in vitro fertilisation (IVF) were compared in the presence and absence of cumulus matrix (which is shed with the oocytes at ovulation). The results show that the presence of this matrix is beneficial because the rates of fertilisation (69%) and monospermy (number of monospermic oocytes/total number of healthy mature oocytes; 42%), and the median number of spermatozoa per oocyte (1.52 +/- 0.06), were improved with respect to those obtained in its absence (54%, 22% and 2.33 +/- 0.08, respectively; p < 0.01). In the second experiment the effect of two different volumes of co-incubation medium (2 ml and 0.4 ml) on the same parameters of porcine IVF were compared. No significant differences between volumes were observed, except in the mean number of spermatozoa per oocyte and the percentage of dispermic oocytes.

Modulation of bovine oocyte-cumulus cell complex maturation and fertilization in vitro by glycosaminoglycans

Oocyte-cumulus cell complex maturation and fertilization potential of 4700 bovine oocytes in the presence of various intrafollicular regulators were studied. Endpoints for oocyte maturation included cumulus cell expansion, retention of [3H]hyaluronic acid, elevated cyclic AMP concentrations, and germinal vesicle breakdown. Media supplemented with FSH and fetal bovine serum stimulated oocyte maturation and fertilization. Heparin and mixed glycosaminoglycans (40% heparan sulfate and 60% dermatan sulfate) stimulated cumulus cell expansion and increased [3H]hyaluronic acid but decreased cyclic AMP and reduced percentages of oocytes with germinal vesicle breakdown at 12 h. Oocytes cultured in heparin or mixed glycosaminoglycans were incapable of fertilization. Addition of serum to oocytes treated with heparin decreased cumulus cell expansion. Addition of FSH to heparin and serum cultures did not overcome the inhibitory effect of serum on heparin-induced expansion. Dermatan sulfate failed to stimulate expansion of cumuli but resulted in cells retaining [3H]hyaluronic acid and elevated cyclic AMP content of oocytes. Dermatan sulfate did not affect the percentage of germinal vesicle breakdown at 12 h. Nitrogen-desulfated heparin did not promote any signs of oocyte maturation. These results demonstrate that heparin and mixed glycosaminoglycans stimulate events related to oocyte maturation but were not capable of preparing oocytes for fertilization. The addition of serum or desulfation of heparin inhibited heparin effects on oocyte maturation.