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PubMed2005

Expression of connexin 43 and gap junctional intercellular communication in the cumulus-oocyte complex in sheep.

To evaluate the effects of FSH, LH and/or cAMP on expression of connexin 43 (Cx43) in the ovine cumulus-oocyte complex (COC) and gap junctional intercellular communication (GJIC) of cumulus cells, two experiments were carried out. In experiment 1, Cx43 was immunodetected in the COC, before or after maturation, obtained from non-treated or FSH-treated ewes. The expression of Cx43 in the COC was greater (P < 0.01) on day 16 than on day 15 of the estrous cycle. In vivo FSH treatment decreased (P < 0.02) Cx43 expression on day 16 but not on day 15 of the estrous cycle. In experiment 2, intact COCs or isolated cumulus cells obtained from small and large follicles from FSH-treated ewes were cultured with or without FSH, LH or cAMP agonist and evaluated for GJIC by laser cytometry. For large follicles, the basal rate of GJIC was greater (P < 0.01) for cumulus cells in intact COCs than for isolated cumulus cells. FSH increased (P < 0.04) GJIC in cumulus cells in intact COCs and tended to increase (P < 0.1) GJIC in isolated cumulus cells from small follicles but decreased (P < 0.01) GJIC in cumulus cells in intact COCs from large follicles. LH also increased (P < 0.01) GJIC in isolated cumulus cells from small follicles but decreased GJIC in intact COCs (P < 0.01) and isolated cumulus cells (P < 0.02) from large follicles. cAMP increased (P < 0.01) the GJIC in both intact COCs and cumulus cells from small and large follicles. These results indicate that day of estrous cycle, stage of maturation and duration of FSH treatment affect expression of Cx43 in ovine COCs. In intact COCs, GJIC in cumulus cells was enhanced, probably due to the presence of the oocyte. In addition, the effects of FSH and LH, but not cAMP, on GJIC of cumulus cells depended on the stage of follicular development and on the presence of the oocyte.

Animals↗
PubMed2001

Antioxidant enzyme activity and oxidative stress in bovine oocyte in vitro maturation.

Reactive oxygen species (ROS) production is a normal process of cell metabolism. In vitro environments usually increase cell production of ROS, which has been implicated as a main cause of cell damage. Nevertheless, the role of ROS in oocyte in vitro maturation (IVM) is controversial. In most cells, enzymatic antioxidant systems can attenuate the effect of oxidative stress by scavenging ROS. The aim of this work was to determine whether: (1) standard conditions of bovine oocyte IVM are responsible for oxidative stress; (2) cumulus cells participate in protection against oxidative stress of the oocyte; and (3) enzymatic antioxidant activity is present in oocytes and cumulus cells. Cumulus-oocyte complexes (COCs) were matured in TCM-199 + 10% steer serum for 24 h at 39 degrees C in 5% CO2:95% humidified air. Oxidative stress was determined by the 2',7'-dichlorofluorescein diacetate assay. Superoxide dismutase (SOD), glutathione peroxidase, and catalase activities were measured spectrophotometrically. Under standard conditions of in vitro maturation, there was no increase in ROS production per COC (P > 0.05), but ROS level per cumulus cell diminished. There was no modification in ROS levels in oocytes matured in the presence versus the absence of their surrounding cumulus cells ( P > 0.05). To the best of our knowledge, the presence of SOD, glutathione peroxidase and catalase activities were detected in oocytes and cumulus cells for the first time. Enzymatic units were lower in denuded oocytes with respect to cumulus (P < 0.05), accounting for 37% for SOD, 25% for glutathione peroxidase, and 11% for catalase of the total COC units. Specific enzyme activity diminished in cumulus cells (P > 0.05) and increased in oocytes due to maturation (P > 0.05). The presence of activity of an enzymatic antioxidant system in the bovine oocyte would regulate in part ROS levels during IVM. Oocytes could be capable of controlling the increase in ROS because of the presence of their own enzymatic antioxidant system, SOD having the highest specific activity with respect to cumulus cells.

Animals↗
PubMed2005

Intracellular cAMP and calcium signaling by serotonin in mouse cumulus-oocyte complexes.

cAMP and intracellular Ca2+ are important second messengers involved in mammalian follicular growth and oocyte meiotic maturation. We investigated the capacity of the neurohormone serotonin (5-hydroxytryptamine, 5-HT) to regulate intracellular cAMP and Ca2+ in mouse oocytes and surrounding cumulus cells. On the basis of a reverse transcription-polymerase chain reaction study, 5-HT7 receptor mRNA is expressed in cumulus cells, oocytes, and embryos up to the four-cell stage, and 5-HT2A and 5-HT2B receptor mRNAs are expressed in cumulus cells only, whereas 5-HT2C, 5-HT4, and 5-HT6 receptors are expressed in neither oocytes nor cumulus cells. The addition of 5-HT (10 nM to 10 microM) to isolated metaphase II oocytes had no effect on their internal cAMP or Ca2+ levels, whereas it caused dose-dependent cAMP and Ca2+ increases in cumulus cells. This cAMP increase in cumulus cells could be mimicked by 5-HT agonists with the following order of potency: 5-HT > 8-hydroxy-2-(di-n-propylamino) tetralin = alpha-methyl-5-HT = 5-carboxamidotryptamine maleate > 2-[1-(4-piperonyl)piperazinyl]benzo-triazole, thereby supporting a preferential involvement of 5-HT7 receptors. As measured with cumulus cells preloaded with fura-2/acetoxymethyl ester (AM), the addition of 5-HT also caused dose-dependent Ca2+ increases, which were probably linked to detected 5-HT2A and 5-HT2B receptors. Adding the Ca2+ ionophore ionomycin to cumulus cells resulted in both Ca2+ and cAMP elevations, whereas preincubation of cells with the Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA)-AM abolished the 5-HT-induced Ca2+ increase and reduced the cAMP increase, indicating cross-talk between the 5-HT-sensitive Ca2+ and cAMP pathways. Our results show that 5-HT may be a local regulator in mouse cumulus-oocyte complexes through its actions on cAMP and Ca2+ signaling, as mediated by 5-HT2A, 5-HT2B, and 5-HT7 receptors.

Animals↗
PubMed1994

Conditioned medium from human cumulus oophorus cells stimulates human sperm velocity.

The objective of this study was to determine whether the cumulus oophorus cells surrounding the human oocyte release a factor(s) that stimulates sperm velocity. Medium from in vitro fertilization (IVF) that was exposed to cumulus/oocyte complexes was tested for its ability to stimulate sperm velocity by use of a computerized sperm motion analyzer. In subsequent experiments, primary cultures of cumulus cells, granulosa cells, and ovarian cancer cells were established, and conditioned medium from these cells was assessed for sperm velocity-stimulating activity. In the initial series of assays using four sperm donors, cumulus/oocyte complex-conditioned medium from IVF increased sperm curvilinear velocity and amplitude of lateral head displacement by an average of 12.3% and 19.3% (p < 0.0001), respectively, compared to medium from IVF that was not exposed to cumulus/oocyte complexes. These results were confirmed in a subsequent, more extensive series of assays using a single sperm donor. Testing of conditioned media after 24 h of primary cell culture showed that cumulus-conditioned medium consistently stimulated curvilinear velocity (8.8% increase) and lateral head amplitude (18.7% increase) compared to unconditioned medium (p < 0.0001) in a manner similar to cumulus/oocyte complex-conditioned medium. In contrast, granulosa-conditioned medium and ovarian cancer cell-conditioned medium did not stimulate curvilinear velocity and lateral head amplitude compared to unconditioned medium. The ability of cumulus-conditioned medium to stimulate curvilinear velocity and lateral head amplitude declined gradually during the 5-day culture period. Nevertheless, the results indicate that the cumulus released velocity-stimulating activity throughout the culture period.(ABSTRACT TRUNCATED AT 250 WORDS)

Culture Media, Conditioned↗
PubMed2002

[Cloned goats produced from the somatic cells of an adult transgenic goat].

This study was carried out to examine the effect of different donor cell type and micro-manipulation on the development of reconstituted embryos. Cultured mural cumulus cells or fibroblast cells from an adult transgenic goat expressing human erythropoietin(rhEPO) were used as the donor cells in nuclear transfer experiments. The reconstituted eggs were generated by transferring fibroblast cells or cumulus cells into the perivitelline space of enucleated M II oocytes and then followed by electrofusion and activation. After 6 days' incubation in vivo, the reconstructed embryos developed into morulae or blastocysts were transferred into 6 foster recipients. Two of the foster-mothers were pregnant and gave birth to two offspring, which were derived from the fibroblast cell and cumulus cell, respectively. Fingerprint analysis showed that the PCR-RFLP patterns of the two offspring were identical to that of donor goats. PCR results indicated that these cloned goats carried hEPO gene as same as their donor cells.

Animals↗
PubMed2000

Paracrine actions of oocytes in the mouse pre-ovulatory follicle.

In mammals, ovulation requires a tight control of extracellular matrix modifications, within both the follicle wall and the inner mass of granulosa cells surrounding the oocyte, namely the cumulus cells. During the pre-ovulatory period, mural granulosa cells promote selective degradation of perifollicular matrix, resulting in the formation of a follicle rupture site. Conversely, cumulus cells synthesize a large amount of a muco-elastic matrix that plays an essential role in the extrusion of the oocyte from the follicle and in the subsequent fertilization process. Formation of such matrix by cumulus cells in the pre-ovulatory follicle appears to be controlled by a paracrine influence by the oocyte. We have shown that mouse oocytes modulate the response of cumulus cells to an ovulatory gonadotropin stimulus by promoting the synthesis and preventing the degradation of cumulus matrix. Therefore, although gonadotropins are essential for triggering the complex events involved in ovulation, the oocyte appears to have an active role in this process. In the present review current data and hypotheses concerning molecular mechanisms involved in the organization and synthesis of cumulus matrix are discussed.

Animals↗
PubMed2003

A stereological study of medium antral follicles during the bovine estrous cycle.

Stereological methods were applied to bovine cumulus-oocyte complexes (COCs) in order to characterize them quantitatively during the estrous cycle. COCs from medium (4-8mm) antral follicles with a compact and complete cumulus mass, and with an uniform or a non-visible ooplasm were aspirated from ovaries of Holstein-Friesian cows, fixed in glutaraldehyde, randomly embedded in glycol-methacrylate, and sectioned at 20 microm. The unbiased nucleator principle was used for estimating the mean volumes of complexes, oocytes, cumulus cells, and nuclei of oocytes and cumulus cells. The thickness of the zona pellucida and the relative numerical percentages of the several morphological types (C1-C3) of cumulus cells were also evaluated. The optical disector procedure was used for cumulus cell sampling. Quantitative data show that COCs appear heterogeneous for all studied parameters. From metestrus to proestrus the volumes of COCs and oocytes remained constant, the volumes of oocytes and oocyte nuclei were correlated, the thickness of the outer zona pellucida decreased, and the relative numerical frequency of follicular type C3 cells increased. Results suggest that COCs from distinct estrus stages are structurally different, with type C3 follicular cells gradually differentiating from cell types C1 and C2.

Animals↗
PubMed2003

Stereological characterization of bovine (Bos taurus) cumulus-oocyte complexes aspirated from small antral follicles during the metestrous and proestrous phases.

Bovine cumulus-oocyte complexes (COCs) aspirated from slaughterhouse ovaries are used for in vitro maturation and fertilization after selection on the basis of morphological appearance of the cumulus and ooplasm. In this context, a quantitative characterization of COCs could provide additional criteria for selecting the most competent complexes. Bovine COCs from small (1-4mm) antral follicles were aspirated from metestrous and proestrous stage ovaries of Holstein-Friesian cows, fixed in glutaraldehyde, randomly embedded in glycol-methacrylate, and sectioned at 20 microm. The unbiased nucleator principle of stereology was used for estimating the mean volumes of complexes, oocytes, cumulus cells, and nuclei of oocytes and cumulus cells. The thickness of the zona pellucida and the relative numerical percentages of the several morphological types (C1, C2 and C3) of cumulus cells were also evaluated. The optical dissector procedure was used for cumulus cell sampling. Quantitative data show that the variability among complexes is generally high, especially for the volume of COCs. There were no linear correlations between the studied parameters, except between the volume of the oocyte and nucleus at metestrus. At proestrus, the volumes of COCs, oocytes and nuclei of oocytes, the volume of follicular cells and the thickness of the inner zona pellucida, were significantly higher than at metestrus. The relative numerical frequency of follicular type C1 cells was lower whereas that of type C3 cells was higher at proestrus than at metestrus. In conclusion, small antral follicles had larger COCs and oocytes at proestrus compared to metestrus and the COCs also had a higher percentage of follicular type C3 cells. Results suggest that for the same type of follicle size there may exist different functional populations of COCs at distinct stages of the bovine ovarian cycle.

Animals↗
PubMed2002

The stage-dependent inhibitory effect of porcine follicular cells on the development of preantral follicles.

The objective of this study was to examine the effects of follicular cells on the in vitro development of porcine preantral follicles. In Experiment 1, one preantral follicle alone (Trt 1) was cocultured with a follicle of the same size with oocytes (Trt 2) or without oocytes (Trt 3). Preantral follicles cultured alone in vitro for 12 days had greater follicle diameters (1017 +/- 96 microm versus 706 +/- 69 or 793 +/- 72 microm, P < 0.05), growth rates (201 +/- 0.3 versus 103 +/- 0.2 or 128 +/- 0.2, P < 0.05) and oocyte survival rates (73% versus 48, or 25%, P < 0.05) than other groups. The inhibitory effects of follicle cells on the growth of preantral follicles and oocyte survival rates were not enhanced by the addition of oocytectomized preantral follicles (Experiment 2). Follicles were cocultured with different sources of follicular cells in other experiments. Coculture with cumulus cells enhanced oocyte survival compared to the control (without coculture) and mural follicular cell groups (Experiment 3). The growth and survival rates of oocytes collected from the group of follicles cocultured with cumulus cells from large antral follicles (>3 mm) were greater (P < 0.05) than those from small antral follicles (<3 mm), or than the control group (without cumulus cells, experiment 4). No significant differences in the follicular diameters (674 +/- 30 microm versus 638 +/- 33 and 655 +/- 28 microm) and growth rate (105% versus 94 and 105%) were observed among the preantral follicles of the different treatments (P > 0.05). Taken together, coculture with the cells from large antral follicles (>3 mm) exerted a significant positive effect on oocyte survival. The growth and oocyte survival of preantral follicle cocultured with the same size of follicles (with or without oocyte) were inhibited. Growth and survival rates of preantral follicles and oocytes are improved by coculturing them with the cumulus cells derived from larger antral follicles.

Animals↗
PubMed2001

Control of mouse cumulus cell-oocyte complex integrity before and after ovulation: plasminogen activator synthesis and matrix degradation.

During the preovulatory period, cumulus cells (CCs) form a hyaluronan-protein extracellular matrix (cumulus expansion) that positively influences oocyte fertilization. Degradation of this matrix and CC-oocyte complex (COC) dissociation occurs within a few hours of ovulation and parallels the aging of oocytes. Modulation of CC proteolytic activity by gonadotropins and oocyte soluble factors has been hypothesized to determine such cumulus matrix changes. In the present study, we investigated plasminogen activator (PA) synthesis by COCs during the expansion and disassembly processes. Our results show that the secretion of tissue type PA and urokinase type PA (uPA) by oocytes and CCs, respectively, does not change significantly during expansion but dramatically increases thereafter. Compact COCs were isolated from immature mice, primed 48 h earlier with 5 IU PMSGs, and were induced to expand in vitro with 100 ng/ml FSH in the presence of 1% FCS. Full expansion was achieved at 16 h, when hyaluronan synthesis ceased. Release of hyaluronan and CCs from the COC matrix began between 18 and 20 h of culture, which indicates that matrix degradation started at this time. PA activities in culture media were determined by SDS-PAGE, followed by a zymography at various time intervals between 4 and 32 h of culture. Secreted tissue type PA and uPA activity abruptly increased between 16 and 20 h after FSH stimulation. Slot blot hybridization of CC messenger RNA showed that uPA messenger RNA levels correlated with the increase in uPA activity. Similar temporal patterns of PA synthesis and matrix degradation were found in COCs induced to expand in vivo by injection of 5 IU human CG into PMSG-primed mice. Cultures of CCs, both in the presence and absence of oocytes, revealed that uPA synthesis is repressed in FSH-stimulated CCs by an oocyte-soluble factor for the first 16 h of culture, whereas CC responsiveness to this factor is lost thereafter. In conclusion, the data show that a sophisticated interplay between oocyte and CCs causes the two cell types to simultaneously secrete PA activity after ovulation. The fact that matrix degradation parallels PA production strongly supports the hypothesis that these enzymes may destabilize the expanded COC matrix.

Animals↗
PubMed2006

Cumulus coculture and cumulus-aided embryo transfer increases pregnancy rates in patients undergoing in vitro fertilization.

OBJECTIVE: To evaluate the effect of the use of cumulus-aided embryo transfer on pregnancy rates. To study the proximity of expanded cumulus cells to the developing embryo. To document by light microscopy the anchoring of day 3 to day 4 embryos by the expanded cumulus cells. To demonstrate by transmission electron microscopy the cellular activity of the expanded cumulus cells. To evaluate the expression of growth factors (vascular endothelial growth factor, interleukin-6, insulin-like growth factor I) that are secreted by the cumulus cells. DESIGN: A comparative study of a group of women undergoing cumulus coculture and cumulus-aided embryo transfer, with those who underwent cumulus coculture but did not undergo cumulus-aided embryo transfer. The endpoint was the achievement of pregnancy. SETTING: Department of Infertility Management and Assisted Reproduction, Jaslok Hospital and Research Centre, Mumbai, India. PATIENT(S): Five hundred seventeen women undergoing treatment for infertility using intracytoplasmic sperm injection and embryo transfer and fulfilling set criteria. To validate our initial results, we conducted a similar study on 208 women where randomization was performed. INTERVENTION(S): Embryos were cocultured with the patient's own cumulus cells and were transferred into the uterus with approximately 30 microL of the expanded cumulus cells. MAIN OUTCOME MEASURE(S): Pregnancy, implantation, and multiple gestation rates. RESULT(S): Our study demonstrated a significant increase in the implantation rate in the study group (group A) of 25.6% versus 14.5% in the control group (group B) and a significant increase in the pregnancy rate in the study group (group A) of 47.6% versus 34% achieved in the control group (group B). Although the incidence of multiple gestation was similar (38.6% in the study group and 32.9% in the control group), the higher-order multiple gestation rate was significantly more in the study group as compared with the control group (18.1% vs. 2.4%). Similar pregnancy and implantation rates were observed in the randomized study. CONCLUSION(S): This study demonstrates the efficacy of cumulus-aided embryo transfer, using autologous cumulus cells. It indicates a significant increase in implantation and pregnancy rates. The results suggest that cumulus cells play an important role in embryonic development, and that they may provide a mechanism to improve embryo-uterine adhesion by physical proximity, and by secreting cytokines and growth factors required to aid the implantation process.

Adult↗
PubMed2002

Function of the cumulus oophorus before and during mammalian fertilization.

CONTENTS: Fertilization encompasses a series of different steps which have to be performed in a well-orchestrated way to create a new individual. They include sperm capacitation, sperm binding and penetration of the zona pellucida, traversing the perivitelline space, binding and fusion with the oolemma, activation of the oocyte and decondensation of the sperm head to form the male pronucleus. In most mammalian species, cumulus cells surround the oocyte at the time of fertilization. Removal of the cumulus oophorus at this point of time often leads to a drop in fertilization rates. It is not yet known how cumulus cells interact with the oocyte or with spermatozoa to promote fertilization. There are different possibilities: 1 cumulus cells cause mechanical entrapment of spermatozoa and guide hyperactivated spermatozoa towards the oocyte, while preventing abnormal spermatozoa to enter the cumulus matrix; 2 cumulus cells create a micro-environment for the spermatozoa which favours their capacitation and penetration into the oocyte; 3 cumulus cells prevent changes in the oocyte which are unfavourable for normal fertilization; these changes can be located in the zona pellucida or in the cytoplasm. In this review, studies in several species are listed to prove the importance of these three cumulus cell functions and the current lines of research are highlighted. Moreover, different ways to improve in vitro fertilization of bovine cumulus-denuded oocytes are discussed.

Animals↗
PubMed1998

Bovine cumulus-corona cells in maturing oocytes. A scanning electron microscopic study.

The ultrastructural features of cumulus-corona cells surrounding maturing oocytes in bovine were studied by means of scanning electron microscope in order to provide a detailed description of their surface changes during oocyte maturation. Cumulus corona cell complexes of immature oocytes showed a compact aspect with narrow intercellular spaces. The spaces around mature oocytes enlarged because they were progressively filled with abundant microfibrillar extracellular matrix. In cumulus corona cells complexes of immature oocytes very numerous long and filiform microvilli were observed, whereas the cumulus corona cell surface surrounding mature oocytes showed occasional large cytoplasmic protrusions along with scanty microvilli and numerous blebs.

Animals↗
PubMed1989

[Ultrastructural localization of prolactin in the cytoplasmic processes of the cumulus granulosa cells and the microvilli of the oocyte in the rat ovary].

The cytoplasmic processes of the cumulus granulosa cells are known to play an important role in connecting these cells with the oocyte, and in supplying nutrition and some to the oocyte for its growth and maturation. And it is also found that the follicular fluid contains prolactin, and that prolactin is present in the cytoplasm of the cumulus granulosa cells and the oocyte when studied by the light microscopic histochemical staining procedure. In this study, we used the protein A-colloidal gold method for transmission electron microscopic observation of the localization of prolactin in the cumulus granulosa cells and the oocyte in the rat ovary. We proved that prolactin is present in the cytoplasmic processes of the cumulus granulosa cells and in the microvilli of the oocyte. Therefore, it is suggested that prolactin is transported from the follicular fluid through the cytoplasmic processes of the cumulus granulosa cells, and that prolactin is absorbed into the oocyte from its microvilli.

Absorption↗
PubMed1990

Identification of extracellular proteins in the rat cumulus oophorus.

We have examined the proteins associated with the mucous matrix of the rat cumulus oophorus and compared them to the composition of rat serum, follicular fluid, ampullary fluid, and oocyte-cumulus cell extract. The cumulus matrix was dispersed using Streptomyces hyaluronidase, and the proteins were analyzed by high-resolution two-dimensional polyacrylamide gel electrophoresis and compared with proteins of the serum, proestrous follicular fluid, and postovulatory ampullary fluid and extracts of oocytes and cumulus cells. In addition to albumin and transferrin, which were common to all the fluids analyzed, the cumulus material contained many proteins in common with the follicular fluid and the ampullary fluid. However, the protein extract of the cumulus matrix also contained four major proteins not present in the other fluids analyzed. Two of these proteins were acidic and heterogenous in charge and size (MW approximately 81,000 and 100,000). The other two proteins were more basic and occurred at MW approximately 90,000 and 150,000. Our results show that the extracellular matrix of the cumulus contains proteins that are not present in the fluids that surround the oocyte.

Animals↗
PubMed1997

Substrate utilization and maturation of cumulus cell-enclosed mouse oocytes: evidence that pyruvate oxidation does not mediate meiotic induction.

This study was performed to address the possible role of pyruvate in meiotic induction in mouse oocytes. Cumulus cell-enclosed oocytes from primed, immature mice were cultured in 7.5 microliters microdrops under oil for 9 or 18 h in medium containing 4 mmol hypoxanthine l-1 plus 0.23 mmol pyruvate l-1, 1 mmol pyruvate l-1, or 1 mmol pyruvate l-1 plus 5.5 mmol glucose l-1. When compared with cultures containing 0.23 mmol pyruvate l-1, 1 mmol pyruvate l-1 induced germinal vesicle breakdown, and this was preceded by an increase in pyruvate utilization. Addition of glucose prevented both the increase in pyruvate consumption and the meiotic induction. When different combinations of pyruvate and glucose were tested on oocyte maturation in microdrop cultures, a high concentration of pyruvate or glucose alone was stimulatory to maturation. Addition of the complementary energy substrate prevented the induction of germinal vesicle breakdown and reduced the amount of substrate consumption. During spontaneous maturation in vitro, oocyte-cumulus cell complexes consumed glucose for the first 3 h; however, during the second 3 h period, which followed germinal vesicle breakdown, glucose consumption decreased and net pyruvate utilization was initiated. Treatment of hypoxanthine-arrested oocytes with dichloroacetate, an activator of pyruvate dehydrogenase, stimulated pyruvate consumption but had no effect on germinal vesicle breakdown. Although FSH stimulates meiotic resumption, no changes in pyruvate consumption were observed in response to this gonadotrophin. Measurement of oxygen consumption by hypoxanthine-treated complexes revealed no effect of high concentrations of pyruvate on respiration, and FSH treatment resulted in a suppression of oxygen utilization. These data indicate that, in mouse oocyte-cumulus cell complexes, pyruvate and glucose can each modulate metabolism of the other substrate, and the can significantly influence meiotic maturation of the oocyte. In addition, augmentation of pyruvate oxidation does not appear to play a mediating role in meiotic induction triggered by energy substrate manipulation or gonadotrophin treatment.

Animals↗
PubMed2004

Human cumulus granulosa cell gene expression: a predictor of fertilization and embryo selection in women undergoing IVF.

BACKGROUND: A biochemical marker for embryo development would increase the chance of a successful pregnancy with IVF by optimizing oocyte and embryo selection, and allow fewer embryos to be transferred. In this study, we correlated cumulus granulosa cell gene expression of hyaluronic acid synthase 2 (HAS2), cyclooxygenase 2 (COX2; PTGS2) and gremlin (GREM1) with subsequent embryo development in search of a parameter for embryo selection. METHODS: Cumulus cell gene expression was determined prospectively on eight consecutive patients undergoing IVF with ICSI. Immediately following oocyte retrieval, the cumulus was stripped from the oocyte, and cumulus gene expression for PTGS2, HAS2 and GREM1 was assessed using a one-step real-time quantitative RT-PCR assay. Oocyte quality, fertilization and embryo morphology were correlated to relative gene expression. RESULTS: Gene expression data were available on cumulus cells from 108 oocytes that developed into 70 embryos (64.8% fertilization rate). Cumulus PTGS2, HAS2 and GREM1 expression was higher from oocytes that developed into higher quality embryos (grades 3, 4 and 5) compared with lower quality embryos (grades 1 and 2) (P<0.05, P<0.001 and P<0.001, respectively). HAS2 and GREM1 expression was also higher from the cumulus surrounding oocytes that gave rise to higher grade embryos (P<0.001). The expression of PTGS2 and HAS2 was 6-fold higher, and that of GREM1 was 15-fold higher in cumulus yielding higher grade embryos versus lower grade embryos. CONCLUSION: PTGS2, HAS2 and GREM1 gene expression correlates to morphological and physiological characteristics and provides a novel approach to predict human embryo development. Ultimately, with better predictors of follicular and embryonic health, higher quality embryos can be selected and transferred, reducing higher order pregnancy rates.

Adult↗