Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Cumulus Cells”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 235 records · Page 13Linked to original sources
PubMed1996

A serum-free medium for use in a cumulus cell co-culture system for bovine embryos derived from in vitro maturation and in vitro fertilization.

The objective of this study was to develop a serum-free medium for the co-culture of bovine embryos that would yield a percentage of blastocysts equal to that obtained with fetal bovine serum (FBS)-supplemented medium. Cumulus cell-enclosed oocytes (CEO) matured and inseminated in vitro were cultured in a tissue culture medium (TCM)-199 or in a serum-free medium (bovine embryo culture medium; BECM) until 240 h post insemination. Replacement of 10% (v/v) FBS with either 3 mg crystallized bovine serum albumin (BSA)/ml or 3 mg fatty acid-free BSA/ml in TCM-199 had no effect (P > 0.14) on embryo development to the >or= 2-cell (51 to 60%), >or= 8-cell (24 to 33%), blastocyst (16 to 19%) and hatched-blastocyst (7 to 10%) stages at 48, 96, 192 and 240 h post insemination, respectively. Oocyte-enclosing cumulus cells in BSA-supplemented medium grew in clusters rather than in layers, as was noted in FBS-supplemented medium. When CEO were cultured in fatty acid-free BSA-supplemented media (TCM-199 and BECM), a significantly (P < 0.001) higher percentage of oocytes developed to blastocysts after culture with (22%) or without (18%) a cumulus cell monolayer than after denuding the oocytes (7%). Glucose in concentrations of 0 to 5.56 mM added for periods of 18 and 120 h post-insemination had neither a stimulatory nor a deleterious effect on preimplantation development. In conclusion, a serum-free medium supplemented with BSA can be successfully used in a cumulus cell co-culture system for bovine embryos.

Journal Article↗
PubMed1988

Kinematics of hamster sperm during penetration of the cumulus cell matrix.

During capacitation, mammalian spermatozoa gain the ability to penetrate the cumulus cell matrix (CCM). The role of hyperactivated motility for this capacity is uncertain. In the present study, hamster sperm were observed during penetration and progression through the CCM, and flagellar beat patterns were quantitated by characterization of the underlying flagellar bends. Small numbers of sperm were added to cumulus masses slightly compressed on a slide (150 micron depth), and penetration was videorecorded using interference contrast optics. During penetration of the cumulus surface, sperm did not generate the large flagellar bends and asymmetric beats that are hallmarks of hyperactivation in low viscosity media. Instead, they entered slowly using high-frequency, low-amplitude sinusoidal flagellar motions. Within the CCM, sperm continued to move slowly, and they exhibited three distinct patterns of motility. The first was sinusoidal, produced by alternating, propagated bends: principal bends (PB) moved the head away from the beat midline, with the convex edge of the head leading, and reverse bends (RB) had the opposite curvature. The second pattern was asymmetric and sinusoidal: an extreme RB developed in the distal flagellum, was propagated distally, and was followed by a PB of less curvature. The third motility pattern was a hatchet-like stroke of the sperm head which resulted when an extreme, nonpropagated PB developed slowly in the proximal midpiece, and was released rapidly. In this mode there were no reverse bends, and sperm did not progress. There were subpopulations of capacitating sperm in free-swimming medium which had these same bend types and motility patterns, suggesting that qualitative flagellar movement may not change during CCM penetration. Sperm velocity in the CCM was not strongly correlated with flagellar beat kinematics, suggesting local heterogeneity in cumulus mechanical resistance and/or differences in interaction of the matrix with the surfaces of individual sperm. An effective viscosity of the cumulus near its border was estimated to be of the order of 1-4 P.

Animals↗
PubMed1990

Effect of removal of cumulus cells from one-cell mouse embryos on in vitro development.

The effects of the removal of cumulus cells from fertilized mouse oocytes (one-cell embryos) and the presence of streptomycin in culture medium on in vitro development were studied. Ham's F-10 medium with (0.075 g/liter) or without streptomycin was supplemented with human serum (15%). Cumulus-intact embryos were harvested from oviducts after mice were superovulated with pregnant mare's serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG). Hyaluronidase (300 IU/ml) was used to remove the cumuli. Embryos were cultured (i) with cumulus/without streptomycin (n = 238), (ii) with cumulus/with streptomycin (n = 185), (iii) without cumulus/with streptomycin (n = 210), and (iv) without cumulus/without streptomycin (n = 218). Embryonic development was assessed 24, 96, and 120 hr after initiation of culture. Percentage two cells and percentage small or expanded blastocysts were not different (P greater than 0.05) among experimental groups. Percentages (mean +/- SE) hatched blastocysts for the four groups were (i) 36 +/- 8 and 54 +/- 7, (ii) 35 +/- 8 and 55 +/- 6, (iii) 19 +/- 5 and 42 +/- 6, (iv) 23 +/- 5 and 47 +/- 5 at 96 and 120 hr, respectively. Percentages all (small, expanded, and hatched combined) blastocysts were (i) 74 +/- 5 and 74 +/- 5, (ii) 74 +/- 9 and 72 +/- 5, (iii) 56 +/- 6 and 63 +/- 5, and (iv) 61 +/- 5 and 63 +/- 5 at 96 and 120 hr, respectively. A greater (P less than 0.05) percentage of embryos developed to blastocysts and hatched by 96 and 120 hr, when they were cultured with the cumulus intact.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Oxygen consumption by rat oocytes and cumulus cells during induced atresia.

Oxygen consumption was measured in denuded oocytes and oocyte-cumulus complexes isolated from atretic rat follicles. Adult cyclic rats or immature PMSG-treated rats were used, and follicular atresia was induced by hypophysectomy on the morning of pro-oestrus or by repeated pentobarbitone injections beginning on the day of pro-oestrus. The later stages of atresia were accompanied by meiosis-like changes in the oocytes. Oxygen consumption by oocytes that had resumed meiosis (germinal vesicle breakdown, GVB) was higher than in oocytes with an intact germinal vesicle, a change similar to that observed in oocytes maturing in healthy follicles. This may indicate that the meiotic process in the atretic follicles is similar to that in normal ones. Oxygen consumption by the cumulus cells was not altered during pentobarbitone-induced atresia. Hypophysectomy led to a rapid and marked increase in cumulus oxygen consumption in cyclic rats but there was no change in PMSG-treated young animals. Since both pentobarbitone-treatment and hypophysectomy result in follicular atresia, but changes in cumulus respiration occurred only in hypophysectomized adult rats, it is concluded that an increase in cumulus respiration is not inherent to the atretic process.

Animals↗
PubMed1985

Metabolic, fluorescent dye and electrical coupling between hamster oocytes and cumulus cells during meiotic maturation in vivo and in vitro.

Heterologous intercellular communication was determined qualitatively by lucifer yellow dye transfer and quantitatively by transfer of radiolabeled uridine metabolites and electrical current in hamster oocyte-cumulus complexes during meiotic maturation in vitro and in vivo. In addition, changes in cell resting potentials during maturation were recorded. Significantly less time was required for germinal vesicle breakdown (GVBD) in oocytes matured in vitro than in oocytes stimulated in vivo (1.81 +/- 0.06 hr, N = 13 vs 2.46 +/- 0.07 hr, N = 18, respectively, P less than 0.001). Resting potentials of the oocyte (RP-o) and cumulus cells (RP-c) significantly increased contemporaneously with GVBD in vitro (RP-o: from -18.9 +/- 3.2 mV to -33.2 +/- 2.9 mV, P less than 0.001; RP-c: from -16.3 +/- 1.9 mV to -27.5 +/- 2.6 mV, P less than 0.001) and in vivo after hCG injection (RP-o: from -16.8 +/- 5.9 mV to -30.1 +/- 3.9 mV, P less than 0.001; RP-c: from -15.5 +/- 3.8 mV to -26.3 +/- 3.2 mV, P less than 0.001). RP-o and RP-c progressively increased with time of culture up to 7 hr (maximum time examined) while the values reached maxima in in vivo matured oocytes 4.5 hr post-hCG and subsequently declined concomitant with the onset of cumulus expansion. Cumulus to oocyte coupling decreased progressively with time after release from meiotic arrest both in vitro and in vivo, as assessed by a progressive reduction in transfer of either uridine marker or lucifer yellow from the cumulus cell to the oocyte. By 4.5 hr after hCG injection, cumulus expansion had begun in 100% of complexes examined. Expansion was extensive by 7 hr post-hCG and spread of lucifer yellow from a cumulus cell was limited to very few adjacent cumulus cells. Oocyte to cumulus cell metabolic coupling also decreased progressively with time in both treatment groups. Examination of the extent of heterologous ionic coupling revealed that ionic coupling exhibited biphasic and, bidirectionally parallel, increases during meiotic maturation. While these temporal changes were observed in both groups, the coupling ratios were much greater in those complexes matured in vitro than in vivo. These results show that dye, metabolic, and electrical coupling exist between the immature hamster oocyte and its surrounding cumulus cells but that during the early stages of meiosis, metabolic and dye coupling decrease, while electrical coupling increases biphasically.

Action Potentials↗
PubMed2007

Assessment of human oocyte developmental competence by cumulus cell morphology and circulating hormone profile.

The predictive value of the morphology of the cumulus--oocyte complex (COC) has not yet been explored as a possible factor contributing to the success of human in-vitro maturation (IVM). In the present study, development-supporting competency of oocytes encircled in a large ( > or = 5) (grade A), moderate (3 approximately 4) (grade B) or small ( < or = 2) (grade C) number of cumulus cell layers was assessed, together with changes in hormonal profile following a truncated course of 150 IU pure FSH administration for 3 days prior to aspiration on laparoscopy indicated for endometriosis. FSH priming increased the number of COC aspirated without changing the proportion of the three morphological types of COC, which were then subjected to IVM in the presence of 200 mIU/ml FSH plus 1000 mIU/ml human chorionic gonadotrophin, followed by intracytoplasmic sperm injection. The highest development-supporting competence was observed not with oocytes in grade A COC harvested from natural cycles, but with oocytes in grade B COC from FSH-primed cycles. Hormonal profiles in patients bearing grade B COC were characterized by moderate response in oestradiol and progesterone production following FSH, with LH/FSH ratio being below 1.0. It is concluded that an optimal window of hormonal profile(s) may exist for follicle aspiration to obtain grade B COC in FSH-stimulated human IVM cycles.

Cell Culture Techniques↗
PubMed1981

Ovarian glycosaminoglycans: evidence for a role in regulating the response of the oocyte-cumulus cell complex to FSH.

The effects of sulfated glycosaminoglycans (GAGs) on FSH-stimulated cumulus expansion and hyaluronic acid (HA) synthesis were tested using cumuli oophori isolated from mice. It was found that heparin (Hep), heparin sulfate (HeS) and chondroitin sulfates (CSs) A,B, and C inhibited FSH-stimulated cumulus expansion and HA synthesis. The relative potencies of these GAGs in inhibiting HA synthesis was as follows: Hep greater than HeS congruent to CS-B greater than CS-C greater than CS-A. The GAGs did not block spontaneous oocyte meiotic maturation. It is suggested that the GAGs may function in vivo to block the response of the cumulus cells to FSH indigenous to the Graafian follicle prior to the preovulatory gonadotropin surge.

Animals↗
PubMed1986

A dramatic loss of cumulus cell gap junctions is correlated with germinal vesicle breakdown in rat oocytes.

Interactions between the cumulus-oophorus and the oocyte have been implicated in the regulation of meiotic maturation. Quantitative analysis of freeze-fractured rat cumulus-oocyte complexes reveals that the net area of cumulus cell gap junction membrane decreases about 15-fold, 2-3 hr following an ovulatory stimulus. This dramatic loss of gap junctions is temporally correlated with germinal vesicle breakdown and cumulus expansion, and is discussed with respect to meiotic maturation and ovulation of the mammalian oocyte.

Animals↗
PubMed1993

Oocytes preserve the ability of mouse cumulus cells in culture to synthesize hyaluronic acid and dermatan sulfate.

A soluble factor(s) produced by fully grown oocytes is essential, together with follicle stimulating hormone (FSH), to stimulate in vitro hyaluronic acid (HA) synthesis by mouse cumulus cells (CCs). The stability of the response to this stimulus by CCs in culture was investigated. The data showed that preculture for 8 hr in basal medium reduced to approximately 30% the ability of CCs to synthesize HA in response to FSH or dibutyryl cyclic AMP (Bt2cAMP) and soluble oocyte factor(s). However, if CCs were precultured for the same period of time as intact cumulus cell-oocyte complexes, or in the presence of fully grown oocytes, or in medium conditioned by fully grown oocytes, their ability to synthesize HA was 75-95% preserved. In vitro stimulation of dermatan sulfate (DS) synthesis by CCs does not require oocyte factors and is induced by FSH or Bt2cAMP treatment alone. However, the preservation of such activity, like that of HA synthesis, depended on the presence of a soluble oocyte factor(s) during preculture. The presence of isolated oocytes or of oocyte-conditioned medium also prevented the spreading of CCs in culture. However, inhibiting CC spreading by culture on agar-coated plates or in serum-free medium did not preserve their HA or DS synthetic activity, thus suggesting that the two oocyte actions on CCs are independent. Growing oocytes were unable both to induce HA synthesis in freshly isolated CCs stimulated with FSH and to preserve the ability to synthesize HA and DS in 8-hr precultured CCs. The results suggest that the stability of the differentiated state of mouse CCs in vitro depends upon continued exposure to a soluble factor(s) produced by fully grown oocytes.

Animals↗
PubMed1991

Progression of oocyte maturation from metaphase I to metaphase II is disturbed by previous immunological interference with cumulus cell function.

The effects of an antibody preparation reacting with preovulatory mouse cumuli oophori (anticumulus Ig) on oocyte maturation in vivo and in vitro were studied. Continuous presence of anticumulus Ig in culture medium did not impair oocyte maturation in vitro. Similarly, no effect on oocyte maturation in vivo was observed when anticumulus Ig was given to females superovulated with pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG) at the time of hCG treatment. However, when administered earlier, anticumulus Ig brought about serious disturbances of oocyte meiotic competence, since only immature oocytes were ovulated after anticumulus Ig injection at the time of PMSG treatment and as much as 70% of the ovulated oocytes were immature when the antibody was applied 24 hr later. Previous absorption of anticumulus Ig with isolated cumulus cells removed the inhibitory effect of this preparation on oocyte meiotic competence to the same extent as absorption with whole cumuli oophori, despite the persistence of a strong reactivity of the cumulus cell-absorbed antibody preparations with the cumulus intercellular matrix. The ability of oocytes obtained from antibody-injected animals to mature in vitro was also considerably impaired when the injection was made at the time of PMSG treatment. In all cases the maturation defect concerned the progression of meiosis from metaphase I to metaphase II, while the ability of oocytes to undergo germinal vesicle breakdown (GVBD) was unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed2000

Increased progesterone secretion and 3 beta-hydroxysteroid dehydrogenase activity in human cumulus cells by pregnenolone is limited to the high steroidogenic active cumuli.

PURPOSE: Several reports imply that lower progesterone secretion by cumulus-oocyte complexes (COCs) is associated with lower fertilization in the corresponding oocyte. The possible role of progesterone in oocyte fertilization in humans was studied using two approaches: (a) increasing the total progesterone secretion by culturing more than one COC per dish; and (b) increasing the cumulus cell progesterone secretion by providing pregnenolone as a substrate. METHODS: Mature COCs were cultured individually or cocultured in groups. Oocyte fertilization and progesterone secretion were tested after 20 hr and 3 days in culture, respectively. The cumuli from individually plated COCs were cultured in the absence of oocyte for an additional 3 days in order to test the effects of pregnenolone on progesterone secretion and the 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) activity. A comparable study with pregnenolone was performed on the corresponding granulosa-lutein cells. RESULTS: Increasing the number of COC to two instead of one led to a significant increase in both fertilization rate and progesterone secretion. The addition of pregnenolone during days 3-6 increased significantly both progesterone secretion and 3 beta-HSD activity. Comparable results were observed in granulosa-lutein cells subjected to pregnenolone treatment. Following the first 3 days culture, cumulus masses were categorized as secreting high or low progesterone levels. Adding pregnenolone had a greater effect on both progesterone secretion and 3 beta-HSD activity in the high-progesterone-secreting cumuli. CONCLUSIONS: Addition of pregnenolone increased progesterone secretion and 3 beta-HSD more efficiently in the higher-progesterone-secreting cumuli. Coculture of two COCs instead of one led to a higher fertilization rate and greater progesterone secretion.

3-Hydroxysteroid Dehydrogenases↗
PubMed1989

RNA and protein synthesis requirements for the resumption of meiosis in rabbit oocytes: the role of cumulus cells.

In vitro maturation of rabbit cumulus-enclosed oocytes was fully inhibited in alpha-amanitin- (100 micrograms/ml) and cycloheximide- (5 micrograms/ml) supplemented media. The inhibition was reversible and substantially reduced by delaying the addition of alpha-amanitin (2h) or cycloheximide (3 h). In contrast, both drugs did not inhibit germinal vesicle breakdown in denuded oocytes. Co-culture of granulosa cells (1 x 10(6)/ml) with denuded oocytes did not substitute for an intact cumulus. The data presented here suggest that the resumption of meiosis in rabbit cumulus-enclosed oocytes is dependent upon early transcriptional and translational events which probably occur within the cumulus cells.

Amanitins↗
PubMed2005

The potential role of gap junction communication between cumulus cells and bovine oocytes during in vitro maturation.

Preliminary studies in our laboratory have indicated that modulating cumulus expansion early or late during culture has a profound influence on the subsequent development of cumulus-enclosed oocytes. Our objectives were to evaluate the effect of short term exposure to recombinant human follicle-stimulating hormone (r-hFSH) during in vitro maturation (IVM) on cumulus expansion and developmental competence of bovine oocytes. A highly significant (P < 0.0001) improvement in blastocyst development rate as a proportion of cleaved oocytes after IVM of oocytes was observed in the presence of r-hFSH for the first 6 hr of culture. To demonstrate the importance of the functional coupling between the oocyte and the cumulus compartment during that period of 6 hr, cumulus-oocyte complexes (COCs) were matured with r-hFSH for the first 6 hr followed by 18 hr in presence of 1-heptanol or 1-octanol (gap junction inhibitors) to block the communication between the two. With the coupling inhibitors, the blastocyst yield was significantly decreased (P < 0.05). A brief treatment (30 min) with the weak base methylamine, known to reverse the gap junction inhibitors effect, significantly (P < 0.05) reversed the inhibitory action of these agents on the blastocyst rate. Gap junction communication between the oocyte and surrounding cumulus cells was further studied using microinjection of the fluorescent dye Lucifer Yellow. Morphological evidences (dye transfer) were obtained that support the presence of functional coupling for a longer period with the FSH short exposure. In conclusion, high developmental rates of bovine oocytes can be achieved with a short exposure to r-hFSH. This effect is believed to be mediated through gap junctions as developmental competence of oocytes is compromised by the inhibition of their function.

Animals↗
PubMed2003

Glutamine and the maintenance of meiotic arrest in mouse oocytes: influence of culture medium, glucose, and cumulus cells.

The selection of culture media and supplements therein has a tremendous impact on the regulation of oocyte maturation in vitro. In the present study, we have evaluated how altering the levels of glutamine in the presence or absence of glucose affects meiotic arrest in cumulus cell-enclosed oocytes (CEO) and denuded oocytes (DO) when cultured in either the simple medium M16 or the more complex Eagle's minimum essential medium (MEM). We have also tested the effectiveness of follicle-stimulating hormone (FSH) in triggering germinal vesicle breakdown (GVB) and purine de novo synthesis in differing MEM culture conditions. When DO were cultured 17-18 hr in hypoxanthine (HX)- or dbcAMP-supplemented M16 medium, neither glucose nor glutamine had any effect on oocyte maturation, with dbcAMP the more effective inhibitor. In the absence of glutamine, cumulus cells promoted meiotic resumption, since significantly lower levels of meiotic arrest were maintained in CEO than in DO by either HX or dbcAMP, but addition of the amino acid dose-dependently decreased the maturation percentage in CEO below that observed in DO. In MEM, glutamine and glucose again had little effect on the maturation of DO, although the percentage of maturing DO in HX-supplemented medium was about 20% lower than that in M16 medium. In the absence of glucose, high levels of maturation were observed in CEO in glutamine-free medium that were dose-dependently lowered by the amino acid. However, when glucose was present, CEO were as effectively arrested as DO when glutamine was absent, with no further effect of the amino acid. This inhibitory action of glucose was dependent on the essential amino acids present in MEM. The effects of glutamine were not due to changes in metabolic coupling between the oocyte and cumulus cells. Measurement of purine de novo synthesis indicated that the maintenance of meiotic arrest as well as FSH induction of meiotic resumption were associated with increases in purine synthesis. We conclude that glucose and glutamine act cooperatively to promote the synthesis of new purine compounds within the somatic compartment and that the timing and duration of such synthesis determines whether meiotic resumption will be suppressed or promoted.

Animals↗
PubMed2003

Decreased expression of tumor necrosis factor-alpha-stimulated gene 6 in cumulus cells of the cyclooxygenase-2 and EP2 null mice.

Ovulation, the release of fertilizable oocytes from mature follicles, involves tissue remodeling and increased prostaglandin (PG) signaling. Cyclooxygenase (COX)-2 is the rate-limiting enzyme during PG synthesis. Female mice null for either COX-2 or the PGE(2) receptor EP2 are infertile, show decreased ovulation, and exhibit abnormal cumulus expansion. Cumulus expansion is the production of a complex extracellular matrix surrounding the cumulus-oocyte complex (COC). Matrix components consist of hyaluronan, proteoglycans, and proteins with hyaluronan binding domains. One such hyaluronan binding protein is TNFalpha-stimulated gene 6 (TSG-6). By various methods, we show induction of TSG-6 and hyaluronan synthase-2 mRNA in ovaries of mice treated with pregnant mare serum gonadotropin and human chorionic gonadotropin. By in situ hybridization, we show that both genes are expressed in periantral mural granulosa cells and cumulus cells of the mouse ovary. Notably, RT-PCR and in situ hybridization show that TSG-6 mRNA but not hyaluronan synthase-2 mRNA expression is selectively reduced in cumulus cells of COX-2 and EP2 null mice. Western analysis further confirms that TSG-6 protein is reduced in isolated COCs but remains covalently associated with inter alpha-trypsin inhibitor in COX-2 null mice. These observations identify TSG-6 as a target of PG action and show that its production in ovulatory follicles is associated with proper formation of the cumulus-derived extracellular matrix.

Alpha-Globulins↗
PubMed2006

Comparative protein expression profiling in human cumulus cells in relation to oocyte fertilization and ovarian stimulation protocol.

Comparative profiling was performed on proteins synthesized in human cumulus cells (CC) from individual oocytes recovered after two different ovarian stimulation protocols for classical IVF (cIVF). Using high-resolution two-dimensional protein electrophoresis after metabolic labelling with [35S]-methionine, protein expression was profiled in CC of metaphase II oocytes obtained after two different ovarian stimulation protocols (rFSH versus human menopausal gonadotrophin). Analysis was done on CC from two cIVF cycles in the same patient and then extended to CC from individual oocytes from two groups of patients. CC from single oocytes have robust levels of protein expression into 600-800 protein spots. Comparison of CC protein expression from oocytes obtained from the same patient but after two different stimulation protocols shows that the type of hormonal treatment influences CC protein expression. In contrast, CC from oocytes obtained under the same stimulation protocol but with different fertilization outcome show a high profile similarity with differences in only a few spots. Comparison of two groups of patients indicates that dissimilarities in protein pattern between patients become very high, even when comparing the same stimulation protocol and oocyte fertilization outcome. Thus protein expression profiling of human CC may provide a correlation between the synthesis of specific cumulus proteins and maturity and fecundity.

Female↗
PubMed2004

Human sperm chemotaxis: both the oocyte and its surrounding cumulus cells secrete sperm chemoattractants.

BACKGROUND: Human sperm chemotaxis to pre-ovulatory follicular fluid is well established in vitro. However, it is not known whether the female's oocyte-cumulus complex secretes sperm chemoattractants subsequent to ovulation (for enabling sperm chemotaxis within the Fallopian tube) and, if so, which of these cell types--the oocyte or the cumulus oophorus--is the physiological origin of the secreted chemoattractant. METHODS: By employing a directionality-based chemotaxis assay, we examined whether media conditioned with either individual, mature (metaphase II) human oocytes or the surrounding cumulus cells attract human sperm by chemotaxis. RESULTS: We observed sperm chemotaxis to each of these media, suggesting that both the oocyte and the cumulus cells secrete sperm chemoattractants. CONCLUSIONS: These observations suggest that sperm chemoattractants are secreted not only prior to ovulation within the follicle, as earlier studies have demonstrated, but also after oocyte maturation outside the follicle, and that there are two chemoattractant origins: the mature oocyte and the surrounding cumulus cells.

Cells, Cultured↗
PubMed2002

Fate of donor mitochondrial DNA in cloned bovine embryos produced by microinjection of cumulus cells.

This study examined the fate of donor mitochondrial DNA during preimplantation development after nuclear transfer (NT) in cattle. Frozen-thawed cumulus cells were used as donor cells in the nuclear transfer. Mitochondrial DNA heteroplasmy in the nuclear transfer embryos was analyzed by allele-specific PCR (AS-PCR), direct DNA sequencing, and DNA chromatography. AS-PCR analysis for the detection of donor mitochondrial DNA was performed at the 1-, 2-, 4-, 8-, 16-cell, morula, and blastocyst stages of the embryos. The mitochondrial DNA from donor cells was detected at all developmental stages of the nuclear transfer embryos. However, mitochondrial DNA heteroplasmy was not observed in direct DNA sequencing of displacement-loop sequence from nuclear-transfer-derived blastocyst embryos. To confirm the mtDNA heteroplasmy in cloned embryos, the AS-PCR product from NT-derived blastocysts was analyzed by DNA sequencing and DNA chromatography. The nucleotides of NT-derived blastocysts were in accordance with the nucleotides from donor cells. These results indicate that the foreign cytoplasmic genome from donor cells was not destroyed by cytoplasmic events during preimplantation development that followed nuclear transfer.

Alleles↗