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At least 19 recordsLinked to original sources
PubMed1979

A comparison between oocyte growth in coculture with granulosa cells and oocytes with granulosa cell-oocyte junctional contact maintained in vitro.

Evidence is presented that strongly supports the hypothesis that the junctional association between oocytes and granulosa cells must be maintained to promote oocyte growth and development in vitro and that the coculture of oocytes with granulosa cells is not a sufficient condition for oocyte development. Furthermore, it is shown that incorporation of uridine and leucine by oocytes into TCA-insoluble material is significantly greater in granulosa cell-enclosed oocytes than in cocultured oocytes.

Animals↗
PubMed1978

Meiotic maturation of mouse oocytes in vitro: protein synthesis in nucleate and anucleate oocyte fragments.

Nucleate and anucleate fragments of mouse oocytes have been isolated following treatment of fully grown oocytes with cytochalasin B. The nucleate oocyte fragments resume meiosis in vitro, progressing from dictyate of the first meiotic prophase to metaphase II ('meiotic maturation'), and exhibit all of the changes in protein synthesis normally associated with meiotic maturation of mouse oocytes. The anucleate oocyte fragments also undergo certain of the changes in protein synthesis associated with meiotic maturation, despite the absence of nuclear progression. These results suggest that the acquisition of meiotic competence (i.e. the ability to undergo meiotic maturation) during growth of the mammalian oocyte is due to changes in the quality, rather than the quantity, of cytoplasm and that the reprogramming of protein synthesis during meiotic maturation is directed by RNA templates already present in the cytoplasm. The behaviour of anucleate oocyte fragments is discussed in terms of the proposed role for nucleoplasm in the initiation of changes in protein synthesis during meiotic maturation of mouse oocytes.

Animals↗
PubMed1979

Oocyte maturation: aberrant post-fusion responses of the rabbit primary oocyte to penetrating spermatozoa.

Primary oocytes cannot be fertilized normally; they begin to develop this capacity as meiosis resumes. To elucidate the changes involved in acquisition of their fertilizability, rabbit primary oocytes displaying a germinal vesicle (GV oocytes) were placed in Fallopian tubes inseminated previously with spermatozoa, recovered 2--5 h later and examined by light and electron microscopy. At least 4 aspects of GV oocyte/sperm interaction were abnormal. Although the vestments and oolemma seem normally receptive to spermatozoa, fusion with the oolemma of the primary oocyte did not elicit exocytosis of cortical granules, and consequently multiple entry of spermatozoa into the ooplasm was common. Secondly, the GV oocyte cortex failed to achieve a normal englufment of the anterior part of the sperm head. It sank into the ooplasm capped by only a small rostral vesicle or left the stable inner acrosomal membrane as a patch in the oolemma. Only rarely then was there significant dispersion of the sperm chromatin, and this remained surrounded by nuclear envelope. The persistence of this envelope constitutes a further aberrant feature, for it disappears immediately in secondary oocytes and was absent in primary oocytes in which germinal vesicle breakdown had occurred. The results are discussed with particular reference to current ideas about male pronucleus formation.

Animals↗
PubMed1979

[RNA-binding proteins of Rana temporaria oocytes: incorporation into informosomes of oocytes in vivo].

The participation of RNA-binding protein in the formation of informosomes in vivo was studied using an intracellular microinjection technique. The RNA-binding protein of the frog Rana temporaria oocytes was isolated by affinity chromatography and was labelled in vitro without any loss of its activity. It was shown that during cultivation of the oocytes the specific incorporation of the injected RNA -- binding [3H]-protein into the ribonucleoprotein particles occurred. These particles were further described as informosomes, characteristic ribonucleoprotein particles of animal cells.

Animals↗
PubMed2026

IL17 signaling promotes oocyte developmental competence acquisition during maturation.

BACKGROUND: Defects in the acquisition of oocyte developmental competence during the maturation process causes subfertility or infertility in animals and humans. Understanding the regulatory mechanisms of oocyte maturation is essential for reproductive biology and medicine. Follicular fluid (FF) is an important microenvironment governing oocyte maturation. METHODS: A tandem mass tags (TMT)-based comparative FF proteomic analysis was employed to identify FF proteins that are potentially crucial for oocyte maturation. A very large number of pig and mouse oocytes (approximately 20,000) and embryos (over 13,000, including somatic cell nuclear transfer, parthenogenetic activation, and in vitro fertilization embryos) were used to investigate the effects of identified FF proteins on in vitro oocyte maturation and subsequent in vitro and in vivo embryo development. RNA sequencing, quantitative PCR, enzyme-linked immunosorbent assays, and immunofluorescence were used to study the expression patterns and action mechanisms of identified FF proteins in oocytes. In addition, intra-oocyte levels of glutathione and reactive oxygen species were measured to assess redox homeostasis. RESULTS: Interleukin 17D (IL17D) was identified as an important FF protein and it is significantly upregulated in porcine FF during oocyte maturation. IL17D promotes oocyte maturation by enhancing bidirectional communication between oocytes and cumulus cells, via upregulating CX43 expression and transzonal projections, which helps to maintain oocyte redox homeostasis and nuclear-cytoplasmic synchrony. IL17D treatment of oocytes enhances subsequent in vitro and in vivo full-term embryo development by modulating lipid metabolism and histone modification reprogramming. IL17D exerts its function via activating IL17 signaling through binding to CD93. Two other IL17 family members, IL17A and IL17F, also enhance oocyte maturation quality. IL17D displays a conserved expression pattern and function in pig and mouse oocytes. CONCLUSIONS: This study reveals the critical roles of IL17D in regulating oocyte developmental competence acquisition during maturation by activating IL17 signaling. The findings provide valuable insights into the molecular mechanisms underlining oocyte developmental potential acquisition and may help to develop methods for efficient production of oocytes for assisted reproduction.

Animals↗
PubMed1979

Germinal vesicle configurations and patterns of polypeptide synthesis of procine oocytes from antral follicles of different size, as related to their competency for spontaneous maturation.

The cytogenetic configurations of germinal vesicle (gv) chromatin were analyzed for pools of porcine oocytes harvested from small (1.0-2.0 mm), medium (3.0-5.0 mm), and large (6.0-10.0 mm) antral follicles. Groups of oocytes from these follicular classes also were examined by high-resolution, two-dimensional, polyacrylamide gel electrophoresis to compare their patterns of polypeptide synthesis. The results show a high incidence of gross and cytogenetic degeneration among oocytes from small antral follicles as compared with those from medium or lage follicles. Pools of oocytes could be separated, on the basis of gross morphology and integrity of adherent granulosa cells, into two classes: "Type A" which appeared normal, and "type B" which appeared to be atretic. Among selected "type A" oocytes a particular chromatin configuration, termed "fibrous" characterizes the gv of oocytes from small follicles; whereas a different configuration, termed "diffuse," characterizes the gv of oocytes from large follicles. The patterns of polypeptide synthesis were markedly different for samples of "type A" oocytes of the three follicular classes; and the patterns for oocytes from medium and large follicles were more similar to each other than to patterns for oocytes from slall follicles. The incidences of maturational development beyond the gv stage in vitro were similar for "type A" oocytes from the three follicular classes (i.e., 66% to 82% maturation); although "type B" oocytes underwent maturation beyond the gv at a significantly reduced incidence (i.e., 20% to 29% maturation). "Type A" oocytes from large follicles completed maturation in vitro (i.e., underwent the first meiotic division) at a significantly higher incidence (55%) than did oocytes from small (11% to 20%) or medium (16%) follicles. Our findings are consistent with the hypotheses that a high proportion of oocytes from small antral follicles are atretic, and that a developmental program controls the molecular and cytogenetic changes occurring in porcine oocytes during follicular growth. These changes appear to be highly correlated with the acquisition of competency to complete maturation in vitro, and possibly also are required for normal fertilization and embryogenesis.

Animals↗
PubMed1979

Nuclear requirement of post-maturational cortical differentiation of amphibian oocytes: effects of cycloheximide.

Cycloheximide induced a complex series of alterations in the cortical cytoplasm of amphibian (Rana pipiens) oocytes undergoing steroid induced nuclear and cytoplasmic maturation in vitro. The morphological changes were described and the role of nuclear-cytoplasmic interactions in the induction of these changes was investigated in intact, enucleated and enucleated-reinjected oocytes. Three stages of cortical changes were ascertained on the basis of: localized alterations at the animal pole, redistribution of pigment and localized contractility (furrow formation) primarily along the animal:vegetal pole axis. The extent and type of cortical alterations varied depending upon the time at which oocytes were examined following hormonal stimulation and cycloheximide treatment. Cycloheximide did not produce cortical alterations in non-hormone treated oocytes nor in steroid treated oocytes until after germinal vesicle breakdown. Nuclear and cytoplasmic maturation and the appearance of cortical alterations were all inhibited when cycloheximide was added to oocytes at the time of steroid treatment. Cycloheximide induction of cortical alterations occurred only after the inhibitor was no longer effective in preventing germinal vesicle breakdown. Enucleated oocytes underwent cytoplasmic maturation in response to the steroid but exhibited no cortical alterations following the delayed addition of cycloheximide. Simultaneous administration of cycloheximide and steroid to enucleated oocytes inhibited cytoplasmic maturation and all observable cortical alterations. Reinjection of nuclear material into enucleated oocytes restored the ability of cycloheximide to induce cortical alterations following steroid induction of cytoplasmic maturation. Without steroid treatment, such reinjected oocytes did not exhibit cortical changes in response to cycloheximide. The data demonstrate that the nucleus is required for and contains a factor(s) which controls the cycloheximide response and post-maturation differentiation of the oocyte. The maturational changes in the cortical cytoplasm appear to be dependent on the intermixing of the germinal vesicle nucleoplasm materials with mature cytoplasm following germinal vesicle breakdown. The results further suggest that the cortical effects of cycloheximide are dependent upon the initiation of protein synthesis during this period of oocyte development. The significance of these observations and experimental studies are discussed in relation to current understanding of the molecular mechanisms controlling meiosis induction and the composition of the germinal vesicle.

Animals↗
PubMed1979

Mammalian oocyte maturation: model systems and their physiological relevance.

Maturation of mammalian oocytes is studied mainly in two dissimilar in vitro models: isolated oocytes maturing spontaneously in culture, and hormone-induced maturation of follicle-enclosed oocytes. In this discussion the following aspects of maturation in vitro in the two aforementioned models were compared: timing of germinal vesicle breakdown (GVB), involvement of cyclic nucleotides, protein synthesis and divalent cations. A third approach to the study of oocyte maturation in vitro, namely oocyte co-culture with follicular constituents was adopted in order to test the role of follicular components in the control of the resumption of meiosis. Such studies demonstrated an inhibitory action of granulosa cells, granulosa cell-conditioned medium and of follicular fluid upon the spontaneous maturation of the co-cultured oocytes. Furthermore, addition of LH to co-cultures of oocytes and granulosa cells induced resumption of meiosis. Although oocytes obtained by spontaneous or by hormone-induced maturation cannot be distinguished morphologically, the developmental potential of oocytes matured spontaneously has been questioned, at least in some species. Furthermore, analysis of the kinetics of spontaneous maturation suggests that oocytes dislodged from their follicles escape physiologic mechanisms ensuring meiotic arrest and skip some of the regulatory steps involved in the normal hormonal triggering of maturation. Oocyte co-culture with granulosa cells offers a close approximation to physiological conditions in that meiotic maturation depends on hormonal stimulation, while the system permits the application of separate treatments to the oocyte-cumulus complex and granulosa cells. As in any in vitro system, critical evaluation is required to discriminate between artifacts inherent in the model and physiological processes.

Animals↗
PubMed1978

The involvement of calcium in the activation of mammalian oocytes.

Mouse oocytes with cumulus cells intact were parthenogenetically activated following release from the oviduct into calcium-free medium. The proportion of activated oocytes increased with post ovulatory age both for oocytes initially exposed to calcium-free and calcium-containing medium (control). Apart from oocytes released shortly after ovulation (approximately 1 h) when less than 1% of the oocytes from treated and control were activated, activation was always higher in oocytes incubated in calcium-free medium (p less than 0.001). The omission of magnesium from the medium had no effect on the activation response of oocytes obtained approximately 3 h after ovulation but its absence did increase the activation rate of oocytes of later post ovulatory age (approximately 9 h after ovulation) although it was still lower than that obtained with media devoid of calcium. When the extracellular calcium was replaced by other divalent cations (strontium, barium and manganese) high rates of activation were obtained even at post ovulatory times which produced relatively low rates of activation in calcium-free medium alone. Similar results were obtained when hamster oocytes were exposed to all the aforementioned treatments. It is concluded that calcium plays an essential role in the activation of the mammalian oocyte but the mechanism of its action remains obscure. Further development of oocytes activated by calcium-free treatment was limited and was similar to that of oocytes activated in other ways.

Animals↗
PubMed1977

Induction of oocytic maturation and differentiation: mode of progesterone action.

Full-grown amphibian oocytes, arrested in prophase I or meiosis, respond in vitro to progesterone and certain other steroids. They undergo an apparently normal sequence of nuclear maturation and cytoplasmic differentiation, which are necessary precedents for fertilization and embryogenesis. Individual oocytes or populations of these cells thus provide a model system for investigations concerning the nature and mechanism of hormone-cellular interactions. In this system, previous studies have shown that certain aspects of hormonal (progesterone, DOCA) induction of morphologic and biochemical differentiation in the nucleus can be induced in part, as a result of the formation of secondary cytoplasmic factors, some of which do not require the presence of the nucleus for their formation. In addition to initiating nuclear events, progesterone or DOCA alters the functional activity of the plasma membrane and establishes the conditions necessary for fertilization and activation. Uptake of radioactive vitellogenin, a yolk protein precursor, was inhibited by progesterone and DOCA. Maximum inhibition was dependent on induction of nuclear breakdown, the dose of steroid used, and was correlated with morphologic alterations at the oocytic surface. Estrone neither stimulated nor inhibited vitellogenin incorporation and had no effect on nuclear breakdown. Oocytic capacity to exhibit activation responses (vitelline membrane elevation) was dependent on oocytic exposure to progesterone or DOCA and development subsequent to the initiation of nuclear breakdown. Onset of the activation response after steroid treatment varied with the type of activation stimulus utilized (pricking or divalent ionophore A-23187). The results suggest that hormones cause ionic alterations in oocytes and that ions are directly involved in the activation response. To study steroid interaction with the cell surface, a method was developed for culturing oocytes that permits localized application of steroids to portions of the oocytic or follicular surface. The results obtained suggest that oocytes exposed to steroid over part of their surface do not respond, with regard to nuclear breakdown, in the same manner as do oocytes exposed over their entire surface to similar concentrations of steroid. Studies of isotopic distribution within the oocyte after local application of steroid indicate that hormone does not readily diffuse through the oocyte. Evidence for the role of cytoplasmic factors in the mediation of nuclear and cytoplasmic events is discussed.

Amphibians↗
PubMed1979

In vitro inhibition of oocyte and follicular maturation and spawning in starfish (Asterias forbesi) by 2-4-dinitrophenol.

The in vitro effects of 2-4-dinitrophenol (DNP) on spawning and follicular and oocyte maturation in starfish ovaries and its various cellular components were investigated. Spawning and oocyte and follicular maturation induced by starfish gonadotropin radial nerve factor (RNF) in isolated ovarian fragments were all inhibited by appropriate doses of DNP. DNP inhibits processes which occur shortly after addition of the gonadotropin; in ovarian fragments insensitivity to DNP inhibition occurred shortly after addition of RNF but prior to initiation of spawning. Spontaneous follicular and oocyte maturation which occurred following release of ovarian follicles into sea water was prevented by DNP. In non-spontaneously maturing follicles released from the ovary, DNP inhibited both follicle and oocyte maturation induced by the secondary stimulator of spawning and maturation, 1-methyladenine (1-MA). DNP also inhibited 1-MA induced meiotic maturation in isolated immature oocytes incubated in the absence of follicle cells. Inhibition of oocyte maturation was not associated with inhibition of 3H-1-MA incorporation by isolated oocytes. Immature oocytes incubated in the presence of DNP underwent maturation following washing and subsequent exposure to 1-MA. Immature oocytes initially exposed to both 1-MA and DNP, however, showed decreased maturation responsiveness following washing and re-exposure to 1-MA. The results suggest that the inhibitory effects of DNP on spawning and oocyte maturation are the result of direct effects on the oocytes and possibly other cells and tissues within the ovary.

Adenine↗
PubMed1977

Somatic nuclei in amphibian oocytes: evidence for selective gene expression.

Previous work has shown that multiple HeLa nuclei injected into Xenopus oocytes remain transcriptionally active for many days and that the expression of HeLa genes in oocytes can be detected by 2-D gel electrophoresis. We show here that of 25 proteins which have the electrophoretic properties of HeLa gene products, only 3 are expressed in injected oocytes. To test that these proteins are products of HeLa genes, and not products of activated oocyte genes, we have injected HeLa nuclei into enucleated oocytes. Three days later, several HeLa proteins were synthesized. The turning off of most HeLa genes in injected oocytes is apparently not at the translational level. This is indicated by the fact that adenovirus mRNA is efficiently translated when injected into Xenopus oocytes. When adenovirus-infected HeLa cells nuclei are injected into oocytes the adenovirus genes are not expressed, although some HeLa genes are expressed by the same nuclei. The same HeLa genes as are expressed or switched off in injected Xenopus oocytes are also preferentially expressed or switched off in injected oocytes of a Urodele amphibian, Pleurodeles. This suggests that conditions or molecules may exist in oocytes which selectively impose on injected nuclei a new programme of gene expression.

Adenoviridae↗
PubMed2026

IVM rescue: Effect of growth hormone supplementation combined to autologous cumulus co-culture on GV oocyte maturation and competency.

OBJECTIVE: IVM rescue is based on the in vitro maturation of mainly Germinal Vesicle (GV) oocytes collected from stimulated cycles. The objective was to investigate the effects of growth hormone (GH) and autologous cumulus cells co culture (CC) on oocyte meiosis resumption and maturation after 32 h post cumulus denudation, in order to obtain additional embryos for the couple as a rescue system to increase the changes of cumulative pregnancy. MATERIAL AND METHODS: Our study concerned 300 patients who underwent ICSI cycles, during which a total of 1940 cumulus-complex-oocytes were retrieved, giving 1260 metaphase II stage (MII), 200 at the metaphase I stage, and 480 at the Germinal Vesicle (GV) stage. Mature oocytes were microinjected on the same day of retrieval. Immature GV oocytes were divided into four groups, with the first undergoing in vitro maturation (IVM) without cumulus cells (group 1) and the second undergoing IVM with CC (group 2), the third undergoing IVM without CC and with GH (group 3), the fourth undergoing IVM with CC and with GH (group 4). After 32 h of IVM, the matured oocytes, underwent microinjection, followed by embryonic development monitoring. RESULTS: When comparing the IVM outcomes, we observed a significant increase in oocyte maturation, fertilization rates and the percentage of 8-cell embryos on day 3 across the different study groups (p < 0.001) (Figs. 2-5). Furthermore, all study groups (1-4) exhibited notably blastulation rates, with group 3 demonstrating the most promising clinical outcomes. A preliminary pregnancy rate of approximately 20% was recorded in group 3, suggesting a potential improvement in the developmental competence of oocytes matured under specific conditions. CONCLUSION: The IVM rescue of germinal vesicle oocyte could serve as an additional strategy to increase the chance getting extra embryos to patients. Autologous cumulus cells co-culture combined to GH supplementation to IVM media, appear to play a crucial role to enhance successful meiosis resumption, oocyte maturation and competency to support embryos development when the injected spermatozoa is not carrier of severe genome and epigenomic decays.

Humans↗