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PubMed1982

Cell interactions and actin synthesis in mammalian oocytes.

In this study, we have examined the profiles of proteins synthesized by mammalian oocytes in the presence and absence of cumulus cells. The results show that the patterns of protein synthesis are broadly similar in cumulus-enclosed and denuded oocytes, but that as a consequence of removing the cumulus cells, the presence of a 45,000-dalton band is greatly reduced. This band, identified by comigration studies on two-dimensional polyacrylamide gels as actin, is strongly synthesized in both isolated cumulus cells and in oocytes labeled in the presence of cumulus cells, but is only weakly synthesized by oocytes incubated in the absence of cumulus cells. We suggest that the presence of newly synthesized actin in the oocyte is dependent upon cellular cooperation between the cumulus cells and oocytes.

Actins↗
PubMed2001

Leukemia inhibitory factor decreases the arylamine N-acetyltransferase activity in human cumulus granulosa cells.

PURPOSE: To evaluate the activities of acetyl coenzyme A (AcCoA):arylamine N-acetyltransferase (NAT) of intact cumulus granulosa cells and the role of leukemia inhibitory factor (LIF) upon their NAT activities. METHODS: Thirty women accepted controlled ovarian hyperstimulation (COH) and oocyte retrievals. Human cumulus granulosa cells were obtained during oocyte retrievals. Using 2-aminofluorene (2-AF) and p-aminobenzoic acid (PABA) as substrates, NAT activity of all samples was determined by high pressure liquid chromatography. After the incubation with different time and concentrations of 2-AF, PABA, and LIF, 2-acetyl-aminofluorene (2-AAF) and N-acetyl-PABA (N-Ac-PABA) were measured. RESULTS: After incubation with 2.812, 5.625, 11.25, and 22.5 microM of 2-AF/PABA, their product concentrations (2-AAF/N-Ac-PABA) were 0.42/0.32, 0.76/0.58, 1.29/1.04, and 1.94/1.26 nmol/10(6) cells, respectively. After 6, 12, 18, and 24 h incubation with 11.25 microM of 2-AF/PABA, their product concentrations were 0.19/0.12, 0.56/0.4, 0.98/0.79, and 1.3/1.0 nmol/10(6) cells, respectively. After incubation with 0, 5, and 50 microM of LIF, the 2-AAF/N-Ac-PABA concentrations were 0.98/0.80, 0.70/0.52, and 0.49/0.30 nmol/10(6) cells, respectively. CONCLUSION: Intact human cumulus granulosa cells could acetylate arylamine carcinogen (2-AF) and noncarcinogens drug (PABA). LIF decreased the NAT activities. It provides a model for monitoring the effects of COH and LIF upon the oocytes.

2-Acetylaminofluorene↗
PubMed2001

Two distinct populations of tumor necrosis factor-stimulated gene-6 protein in the extracellular matrix of expanded mouse cumulus cell-oocyte complexes.

After the luteinizing hormone surge, the cumulus cell-oocyte complexes (COCs) in the preovulatory follicles produce a viscoelastic extracellular matrix, a process that requires the synthesis of hyaluronan as well as the incorporation of some components of the inter-alpha-trypsin inhibitor (IalphaI) family. In this study we report, that a hyaluronan-binding protein, the translated product of tumor necrosis factor-stimulated gene-6 (TSG-6), is also specifically accumulated in this matrix. TSG-6 mRNA expression is quickly upregulated and peaks at approximately 1500 copies/cell 4 h after the ovulatory stimuli as assessed by quantitative reverse transcription-polymerase chain reaction. Immunohistochemistry reveals the colocalization of the TSG-6 protein and hyaluronan around the cumulus and granulosa cells. The TSG-6 protein exists in two distinct populations in the COC matrix as demonstrated by Western-blot analysis. One population is a monomer that is anchored to the matrix by a noncovalent interaction. The second population is a covalent complex with either of the heavy chains of IalphaI and is bound to hyaluronan through a strong interaction that is resistant to denaturing conditions. The specific incorporation of the TSG-6 protein into the COC matrix suggests a structural role for this molecule.

Alpha-Globulins↗
PubMed1976

Effects of gonadotrophins on the cumulus oophorus of isolated rat Graafian follicles.

Graafian follicles were extirpated before the endogenous LH surge on the day prior to ovulation from PMS-injected immature rats. They were incubated in chemically defined medium in presence or absence of gonadotrophins for 4-10 h. After incubation the oocyte-cumulus complexes were recovered from the follicles and one group inspected by Nomarski interference contrast microscopy and one group was placed in saline containing hyaluronidase. In hormone-free medium both the oocyte and the cumulus cells remained morphologically unchanged: a dictyate oocyte surrounded by a compact mass of cumulus cells. Hyaluronidase did not detach cells from the cumulus structure. However, in presence of LH or FSH morphological changes developed in both cell types: the oocyte resumed meiosis as revealed by germinal vesicle breakdown and polar body formation; the cumulus structure became dispersed and embedded in a viscous matrix. The individual cumulus cells displayed pseudopodia-like processes of the cell surface. Treatment with hyaluronidase resulted in detachment of cells from the cumulus. The effects of LH described on the oocyte and cumulus cells were unimpaired in presence of cyanoketone or aminoglutethimide although these agents blocked the follicular relase of progesterone, estradiol and androstenedione as revealed by RIA. The results indicate that a close functional relationship exists between the two cell types of the cumulus oophorus, the oocyte and the cumulus granulosa cells. Both cell types are affected directly or indirectly by gonadotrophins and characteristical morphological changes develop synchronously in both cell types.

Aminoglutethimide↗
PubMed2003

Bovine cumulus-granulosa cells contain biologically active retinoid receptors that can respond to retinoic acid.

Retinoids, a class of compounds that include retinol and its metabolite, retinoic acid, are absolutely essential for ovarian steroid production, oocyte maturation, and early embryogenesis. Previous studies have detected high concentrations of retinol in bovine large follicles. Further, administration of retinol in vivo and supplementation of retinoic acid during in vitro maturation results in enhanced embryonic development. In the present study, we hypothesized that retinoids administered either in vivo previously or in vitro can exert receptor-mediated effects in cumulus-granulosa cells. Total RNA extracted from in vitro cultured cumulus-granulosa cells was subjected to reverse transcription polymerase chain reaction (RT-PCR) and mRNA expression for retinol binding protein (RBP), retinoic acid receptor alpha (RARalpha), retinoic acid receptor beta (RARbeta), retinoic acid receptor gamma (RARgamma), retinoid X receptor alpha (RXRalpha), retinoid X receptor beta (RXRbeta), retinaldehyde dehydrogenase-2 (RALDH-2), and peroxisome proliferator activated receptor gamma (PPARgamma). Transcripts were detected for RBP, RARalpha, RARgamma, RXRalpha, RXRbeta, RALDH-2, and PPARgamma. Expression of RARbeta was not detected in cumulus-granulosa cells. Using western blotting, immunoreactive RARalpha, and RXRbeta protein was also detected in bovine cumulus-granulosa cells. The biological activity of these endogenous retinoid receptors was tested using a transient reporter assay using the pAAV-MCS-betaRARE-Luc vector. Addition of 0.5 and 1 micro molar all-trans retinoic acid significantly (P < 0.05) increased the activity of the pAAV-MCS-betaRARE-Luc reporter compared to cells transfected with the control reporter lacking a retinoic acid response element. Addition of 5 or 10 micro molar all-trans retinol stimulated a mild increase in reporter activity, however, the increase was not statistically significant. Based on these results we conclude that cumulus cells contain endogenously active retinoid receptors and may also be competent to synthesize retinoic acid using the precursor, retinol. These results also indirectly provide evidence that retinoids administered either in vivo previously or in vitro may have exerted a receptor-mediated effect on cumulus-granulosa cells.

Animals↗
PubMed2003

Impaired cumulus mucification and female sterility in tumor necrosis factor-induced protein-6 deficient mice.

Mucification of the cumulus layer around the oocyte is an obligatory process for female fertility. Tumor necrosis factor-induced protein-6 (TNFIP6 or TSG6) has been shown to be specifically expressed during this process. We have generated TNFIP6-deficient mice and tested the ability of their cumulus cells to undergo mucification. Cumulus cell-oocyte complexes fail to expand in TNFIP6-deficient female mice because of the inability of the cumulus cells to assemble their hyaluronan-rich extracellular matrix. The impaired cumulus matrix formation is due to the lack of covalent complexes between hyaluronan and the heavy chains of the inter-alpha-trypsin inhibitor family. As a consequence, TNFIP6-deficient females are sterile. Cultured TNFIP6-deficient cumulus cell-oocyte complexes also fail to expand when stimulated with dibutyryl cyclic AMP or epidermal growth factor. Recombinant TNFIP6 is able to catalyze the covalent transfer of heavy chains to hyaluronan in a cell-free system, restore the expansion of Tnfip6-null cumulus cell-oocyte complexes in vitro, and rescue the fertility in Tnfip6-null females. These results provide clear evidence that TNFIP6 is a key catalyst in the formation of the cumulus extracellular matrix and indispensable for female fertility.

Animals↗
PubMed1989

Zona drilling increases the penetrability of rat oocytes matured in vitro.

Immature rat follicular oocytes were cultured either with cumulus cells intact (CI) or cumulus-free (CF) in bovine serum albumin (BSA)- or serum-supplemented medium under conditions in which meiotic maturation occurs spontaneously. After 12 h of culture to permit in vitro maturation (IVM), the cumulus cells were stripped from the CI group. Control oocytes recovered 2-4 h after ovulation from oviducts of pregnant mare's serum gonadotropin (PMSG)-treated rats were similarly stripped of cumulus cells. Half the oocytes in each group had holes "drilled" in their zonae pellucidae by topical application of acid Tyrode's solution with a micropipette to enable bypass of the zona barrier to penetration. They were cultured for a further 14-16 h with epididymal sperm and then were assessed for sperm penetration and pronuclear formation. In a preliminary study using various concentration of sperm, 50,000 sperm/ml was identified as an appropriate concentration and was used in all subsequent experiments. For oocytes matured in serum-supplemented medium, penetration rates of non-drilled oocytes-expressed as a percentage of oocytes exposed to sperm for CF, CI, and ovulated oocytes were 10%, 34%, and 80%, respectively (p less than 0.01). Drilling significantly increased the penetration rates of both IVM groups (CF: 40%, CI: 77%) but not of ovulated oocytes (78%). Forty-one percent of non-drilled CF oocytes failed to form normal pronuclei after penetration. This was significantly higher than either the CI (0%) or ovulated (1%) groups (p less than 0.001). Drilling increased the incidence of failure to form normal pronuclei in penetrated oocytes of the CF group (64%) but not of the CI or ovulated groups.2z=

Animals↗
PubMed1996

Activation of protein kinase A and protein kinase C mediates the depolarising effect of LH in ovine cumulus-corona cells.

We have studied the changes in membrane potential induced by LH in cumulus and granulosa cells isolated from sheep antral follicles. The investigation was carried out by using a non-invasive technique based on the use of a membrane potential sensitive probe, bis-oxonol. The membrane potential of mural granulosa cells was totally unaffected by LH, while that of cumulus or corona cells showed a marked depolarisation, starting 2-3 min after the addition of the hormone and plateauing after 5-10 min. None of the cells tested reacted to FSH. In the second part of the experiment the role of protein kinase A (PKA) and protein kinase C (PKC) in mediating the effect of LH was studied. The selective activation of PKA or PKC induced in cumulus-corona cells a rapid hyperpolarisation due to increased Cl and K conductance respectively. By contrast, the simultaneous activation of the two kinases induced a rapid membrane depolarisation due to the progressive decrease in K conductance. The activation of each kinase or their combined stimulation did not induce any change in the membrane potential of mural granulosa cells. These data demonstrated that LH has a depolarising effect regionally circumscribed to cumulus-corona cells and that this depolarisation depends on a reduction of K conductance caused by the activation of PKA and PKC.

Animals↗
PubMed2000

Signal transduction mechanism for LH in the cumulus-oocyte complex.

The paper reviews recently described signalling mechanisms by which cumulus cells exposed to peak levels of gonadotropins, activate oocyte maturation. Cumulus cells react to LH with a prompt Ca raise which diffuses through gap junctions in a few minutes also into the oocyte where a local amplification system spreads the signal all over the cell. Few h later, still as a consequence of LH stimulation, cumulus cells undergo aprogressive depolarisation of their plasma membrane potential. Due to the electric coupling with these cells the oocyte depolarises too and this open specific voltage gated Ca channels responsible for a second wider and more sustained intracellular Ca rise. As a result of changes throughout maturation with a consequent modification of the size and charge of the molecules that can diffuse from one cell compartment to the other. This cell to cell interaction is further modified with cumulus expansion that leads to a progressive uncoupling of outer cumulus cells while the inner cell layer, corona radiata, remains in oocyte maturation by addressing to the oocyte nutrients and instructions in a well-orchestrated sequence. The identification of these mechanisms are a fundamental prerequisite for the development of in vitro systems suitable to produce oocytes matured in vitro with normal developmental competence.

Animals↗
PubMed2003

[Some factors affecting in vitro development of porcine embryo reconstitution from somatic cells nuclear transfer].

In this paper, a study on reconstitution of porcine oocytes by using nuclear transfer with cumulus cells(CC) and fibroblast cells(FC) was carried out. Reconstituted oocytes which were the fusion with CC and showed a cleavage rate of 56.7%, developed to morula(11.7%) and blastocysts(6.7%) phases which were higher than those derived from the fusion with FC(p < 0.05). The results of this study also involved the effects of oocyte collection method and maturational age of recipient oocytes during the in vitro development of nuclear-transfer embryos which were reconstructed with cultured cumulus cells. The cumulus cells synchronized in G0/G1 phases through serum-starvation culture, were transferred into enucleated oocytes which were collected by aspiration or dissection method and cultured for 33 or 44 h. Reconstituted embryos were activated with a combination of calcium ionophore A23187 or electric pulsation and 6-DMAP, and cultured for 6 days. As for the oocytes collection methods, activation treatment in the presence of cytochalasin B did not affect the developmental rate of embryos reconstituted with 44-h-mature recipients. However, the development rate of reconstituted embryos with 33-h-mature recipients was significantly higher(p < 0.05) by activation with the combination of electric pulsation and 6-DMAP. These results suggest that reconstituted porcine embryos derived from cultured cumulus cells can develop to the blastocyst stage and that the development of the former could be improved by reconstruction with young oocyte cytoplast after the activation with the combination of electric pulsation and 6-DMAP.

Adenine↗
PubMed2002

Activity of key enzymes involved in glucose and triglyceride catabolism during bovine oocyte maturation in vitro.

Little is known about the metabolic profile of cumulus-oocyte complexes (COCs) during maturation. The aim of this study was to determine the differential participation of enzymatic activity in cumulus cells and the oocyte during in vitro maturation of bovine oocytes, by measuring the activity of key enzymes involved in the regulation of glycolysis (phosphofructokinase), the pentose phosphate pathway (glucose-6-phosphate dehydrogenase) and lipolysis (lipase). COCs were matured in medium 199 plus 10% (v/v) steer serum for 22-24 h at 39 degrees C in 5% CO(2):95% humidified air. Phosphofructokinase, glucose-6-phosphate dehydrogenase and lipase activities were measured in immature and in vitro matured COCs, denuded oocytes and cumulus cells, respectively. Phosphofructokinase and glucose-6-phosphate dehydrogenase activities (enzymatic units) remained constant during in vitro maturation of COCs, but there was a significant decrease in lipase activity (units) (P < 0.05), as activity in cumulus cells decreased significantly (P < 0.05). For the three enzymes studied, enzyme activity (units) remained unchanged in the oocyte during in vitro maturation. Specific activity increased in the oocyte (P < 0.05) and decreased in cumulus cells as a result of maturation (P < 0.05). In cumulus cells, phosphofructokinase was the most abundant of the three enzymes followed by glucose-6-phosphate dehydrogenase and then lipase (P < 0.05), whereas in the denuded oocyte this order was reversed (P < 0.05). Thus, the metabolism of cumulus cells is adapted to control the flow of metabolites toward the oocyte, which maintains its enzymatic activity even when dissociated from cumulus cells during maturation. The high activity of phosphofructokinase in cumulus cells indicates that glucose is metabolized mainly via the glycolytic pathway in these cells. The greater relative activity of glucose-6-phosphate dehydrogenase recorded in the oocyte indicates that glucose uptake could be directed mainly toward the pentose phosphate pathway. The marked lipolytic activity concentrated in the oocyte indicates an active participation in lipid catabolism during maturation.

Animals↗
PubMed1991

The meiotic response of cumulus cell-enclosed mouse oocytes to follicle-stimulating hormone in the presence of different macromolecules.

Experiments were carried out to determine the effect of different macromolecules on the follicle-stimulating hormone (FSH)-induced maturation of mouse oocytes in culture. Cumulus cell-enclosed oocytes (CEO) were isolated from gonadotropin-primed mice and maintained in meiotic arrest for 17-18 h with the cAMP analogue, dibutyryl cAMP (dbcAMP). Germinal vesicle breakdown (GVB) was stimulated by the addition of FSH. Medium was supplemented with either no macromolecule or with varying concentrations of polyvinylpyrrolidone (PVP), polyvinylalcohol (PVA), crystallized bovine serum albumin (BSA), or fetal bovine serum (FBS). Oocyte maturation in all FSH-free cultures occurred at a frequency of about 30% or below. High frequencies of maturation were achieved when FSH was added to macromolecule-free medium or to cultures containing PVP, PVA, or BSA. Crystallized BSA was the most effective of these in supporting stimulation of maturation (94% GVB at 3 mg/ml, compared with 72-74% with synthetic polymer-supplemented or macromolecule-free media). The BSA effect was not due to contaminating fatty acids, and a less pure fraction V BSA was not as effective in supporting FSH-induced maturation. FBS suppressed FSH stimulation of maturation in a dose-dependent fashion. Sera from pigs, goats, horses, and rats were also inhibitory, but bovine calf serum (BCS) permitted a high maturation frequency (80% GVB). When added to medium containing either FBS or BCS, crystallized BSA had no effect on FSH-stimulated maturation, but fraction V BSA suppressed maturation in both serum-supplemented media. Under no conditions did FSH stimulate maturation in cumulus cell-free oocytes. These results demonstrate that hormone-induced oocyte maturation is supported in vitro by nonprotein polymers as well as BSA and that the behavior of the oocyte-cumulus cell complex depends on the purity of the BSA sample. In addition, serum contains inhibitory factors that suppress the positive response to FSH. Thus, the choice of macromolecular supplement is of critical importance when testing the hormone responsiveness of isolated cumulus cell-enclosed oocytes in culture.

Animals↗
PubMed1985

Effect of follicle-stimulating hormone on cyclic adenosine monophosphate level and on meiotic maturation in mouse cumulus cell-enclosed oocytes cultured in vitro.

We have reported that in vitro treatment with follicle-stimulating hormone (FSH) delays by about 3 h spontaneous meiotic resumption in cumulus cell-enclosed mouse oocytes. In the present paper we show that the temporary meiotic block is accompanied by a transient increase of cAMP concentration in the oocyte. In cumulus cell-oocyte complexes stimulated with 1 microgram/ml FSH, cAMP significantly increases within 1 h both in the whole complex (from a basal value of 1.9 +/- 0.2 to 169 +/- 13 fmol) and in the enclosed oocyte (from 0.9 +/- 0.2 to 2.4 +/- 0.2 fmol), then progressively decreases to basal values. Stimulation by FSH does not cause any cAMP increase in denuded oocytes. As the concentration of cAMP in the cells decreases, the percentage of oocytes escaping the meiotic block imposed by FSH increases. If the complexes are cultured in the presence of 1 microgram/ml FSH plus 1 mM isobutyl-1-methylxanthine (1BMX), cAMP concentration increases approximately 250-fold in the complex, and 10-fold in the enclosed oocyte; the level of cAMP in the oocyte drops very rapidly (50% degradation in less than 2 min) if the oocyte is then transferred to IBMX-free medium. The data are discussed in terms of the possible role of cAMP transfer from cumulus cells to the oocyte in the regulation of meiotic progression in mouse oocytes.

1-Methyl-3-isobutylxanthine↗
PubMed1992

Interleukin-1: local production and modulation of human granulosa luteal cells steroidogenesis.

OBJECTIVES: To investigate the possibility of local interleukin-1 (IL-1) and IL-1 inhibitor production by human granulosa and cumulus cells and to assess their direct effects on the steroidogenesis of these cells in vitro. DESIGN: Prospective study. PARTICIPANTS: Normal ovulatory women undergoing ovulation induction for in vitro fertilization. INTERVENTION: Pretreatment of patients with gonadotropin-releasing hormone analogue, human menopausal gonadotropin, and human chorionic gonadotropin (hCG). MAIN OUTCOME MEASURES: Retrieval and isolation of granulosa luteal cells and follicular fluid (FF). Granulosa luteal cells and cumulus cells cultured and analyzed by fluorescent activated cell sorter. Follicular fluid separated and bioassayed for IL-1 and IL-1 inhibitory activity. Steroid measurement performed. Interleukin-1 inhibitor purified. Interleukin-1 and IL-1 inhibitor bioassay performed. Statistical analysis made and interpreted. RESULTS: Interleukin-1, but not IL-1 specific inhibitory activity, was found in granulosa and cumulus cell cultures and also in FF, only after its purification on a high-pressure liquid chromatography column. Under nonstimulated conditions, neither IL-1 nor IL-1 inhibitor had any effect on basal progesterone (P) or estradiol (E2) secretion. However, IL-1 inhibitor demonstrated significant (P < 0.01) inhibition of hCG-stimulated P secretion (from 200 to 110 ng/10,000 cells per 24 hours). In addition, IL-1 demonstrated a significant (P < 0.05) and dose-dependent inhibition of hCG-stimulated E2 production (from 6,832 +/- 460 to 4,237 +/- 141 pg/10,000 cells per 24 hours). CONCLUSIONS: Interleukin-1 may exert a significant local autocrine regulatory role in the human ovary.

Cells, Cultured↗
PubMed2000

Presence of Fas-Fas ligand system and bcl-2 gene products in cells and fluids from gonadotropin-stimulated human ovaries.

Apoptosis, or programmed cell death, is an important mechanism for the regulation of embryonic development and tissue homeostasis. It is coordinated by a number of molecules including the Fas-Fas ligand (FasL) system and bcl-2. The purpose of this study was to characterize the expression of these molecules in human oocytes and cumulus cells from gonadotropin-stimulated human ovaries and to determine whether the presence of soluble Fas (sFas), soluble FasL, or interferon-gamma in follicular fluid (FF) correlated with apoptosis in cumulus cells, oocyte maturation, and embryo quality. Levels of sFas were significantly higher in FF containing immature oocytes compared with those containing atretic oocytes (P < 0.05; FF containing mature oocytes had highly variable levels of sFas. Levels of sFas in FF did not correlate with either fertilization, embryo quality resulting from fertilized oocytes, or apoptosis rate in cumulus cells. Fas was expressed in both unfertilized oocytes and cumulus cells, whereas FasL expression was not usually detected in these cell types. Messenger RNA for bcl-2 was detectable in both freshly isolated oocytes and cumulus cells but was not demonstrable following 24 h of culture that coincided with a significant increase of apoptosis in cumulus cells. Our results indicate that soluble forms of the Fas-FasL system are present in FF from gonadotropin-stimulated human ovaries and suggest that this system may play a role in preventing oocyte atresia during folliculogenesis but is probably not important for apoptotic events in cumulus cells and oocytes after fertilization failure. Apoptosis in this case may be facilitated by the downregulation of bcl-2. Further studies on the expression of these molecules in follicles containing atretic oocytes and immature oocytes are needed to confirm this new hypothesis.

Apoptosis↗
PubMed2003

Expression of messenger RNA for prostaglandin E receptor subtypes EP4/EP2 and cyclooxygenase isozymes in mouse periovulatory follicles and oviducts during superovulation.

Prostaglandin (PG) E(2) is synthesized from arachidonic acid by cyclooxygenase (COX) and acts as a regulator in ovulation and fertilization reactions. We present the temporal and regional expression patterns of mRNAs for the two Gs-coupled PGE receptors, EP2 and EP4, and for COX-1 and COX-2 in mouse periovulatory follicles and oviducts during superovulation. Analysis using reverse transcription polymerase chain reaction revealed that the mouse ovaries express a significant amount of EP4 mRNA in addition to EP2 mRNA during superovulation. In situ hybridization results revealed that the signals for EP4 mRNA were localized mostly to oocytes in the preantral follicles. Three hours after hCG injection, the signals for EP4 and EP2 mRNA were present in both granulosa and cumulus cells. However, 9 h after hCG injection, just before ovulation, the signals for EP4 mRNA were still detectable in both cell types, whereas those for EP2 mRNA were found only in cumulus cells. COX-2 mRNA expression was present in both granulosa and cumulus cells at 3 h but was present only in cumulus cells at 9 h. COX-1 mRNA expression was not found in granulosa cells at 3 h but was found in these cells at 9 h. In the oviduct, the expression of EP4 and COX-1 mRNA was localized to epithelial cells, whereas expression of EP2 mRNA was localized to the smooth muscle layer. The tightly regulated expression of both EP2 and EP4 in the preovulatory follicles may reflect the essential role of PGE(2) in the ovulation process.

Animals↗
PubMed1985

An electron microscopic study of sperm penetration into the human egg investments.

The ultrastructure of human spermatozoa located in the cumulus cells and the zona pellucida of a pro-nuclear egg, and in the zona pellucida of a two-cell egg, both fertilized in-vivo, has been analysed in order to understand how the human spermatozoon penetrates the investing coats of the oocyte. Among the 36 spermatozoa found in the cumulus cells, 31 were phagocytosed by cumulus cells and 5 were wedged in the matrix between the cells. These spermatozoa were acrosome-reacted and their equatorial segment was intact. Six of the seven spermatozoa found in the zona pellucida (four spermatozoa in the pronuclear egg and three in the two-cell egg) had lost the equatorial segment, while the other one was partially reacted. The sperm heads were located in slits with sharp edges. From these findings it was concluded that in the human (1) only few and normal spermatozoa seem to reach the cumulus cells after natural insemination, (2) the acrosome reaction probably occurs sometime before the spermatozoa reach the vicinity of the corona cells, (3) the reaction of the equatorial segment seems to occur during or before the initial phase of zona penetration, since the spermatozoa located in the matrix of the zona pellucida had no equatorial segment. No evidence of the presence of spermatozoa with an intact acrosome in the matrix of cumulus cells or with an intact equatorial segment in the zona pellucida were found.

Female↗
PubMed2005

Prolactin receptor mRNA expression in oocytes and preimplantation mouse embryos.

Prolactin was first identified as an anterior pituitary lobe hormone, responsible for the regulation of mammary gland growth and development. Prolactin receptors have been localized in a number of peripheral tissues, including tissues involved in reproduction. Studies with knockout animals have shown that prolactin receptor deficient mice present reproductive defects, whereas prolactin promotes the developmental potential of preimplantation mouse and rat embryos in vitro. To better understand the role of prolactin in the process of reproduction and early embryo development in mice, the expression of the four transcript variants of prolactin receptor was examined in the first stages of mouse embryo development. Prolactin long receptor mRNA was expressed in all stages examined, that is in cumulus cells, oocytes, zygotes, 2-cell embryos, 4-cell embryos, morulae and blastocysts. Prolactin receptor type S1 mRNA was observed only in cumulus cells, while S2 mRNA was present in cumulus cells, oocytes, zygotes and 2-cell embryos. S3 mRNA was expressed only in cumulus cells and oocytes. These results indicate that different isoforms of prolactin receptors may be present in the various stages of mouse preimplantation embryo and may play an important role in the control of its growth and development.

Animals↗