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PubMed2005

Strategies in human in-vitro maturation and their clinical outcome.

The basis of in-vitro maturation (IVM) is the maturing in vitro of oocytes from the germinal vesicle (GV) stage of development to the metaphase II stage. Experience in handling immature oocytes has been obtained from two main groups. The first group is women suffering from polycystic ovarian syndrome, who are extremely sensitive to stimulation with exogenous gonadotrophins in assisted reproduction, and have a significant risk of developing ovarian hyperstimulation syndrome (OHSS). The second group is regular cycling women with normal ovaries referred for IVF due to severe male infertility. In both groups, aspiration of immature oocytes has been performed in unstimulated cycles and after priming with human chorionic gonadotrophin or FSH respectively. Clinical pregnancy rates of 24% per aspiration have been obtained. Children born after IVM appear to be healthy. These data, taken together, suggest that in future, immature oocyte retrieval combined with IVM could replace conventional IVF in selected patients.

Adult↗

PubMed2003

Use of heterologous complementary DNA array screening to analyze bovine oocyte transcriptome and its evolution during in vitro maturation.

We have analyzed gene expression in bovine oocytes before and after in vitro maturation (IVM) using heterologous hybridization onto cDNA array. Total RNA was purified from pools of over 200 oocytes either immediately after aspiration from follicles at the surface of slaughterhouse cow ovaries or following in vitro maturation. Radiolabeled cDNA probes were generated by reverse-transcription followed by linear PCR amplification and were hybridized to Atlas human cDNA arrays. To our knowledge, this is the first report of gene expression profiling by this technology in the mammalian female germ cell. Our results demonstrate that cDNA array screening is a suitable method for analyzing the transcription pattern in oocytes. About 300 identified genes were reproducibly shown to be expressed in the bovine oocyte, the largest profile available so far in this model. The relative abundance of most messenger RNAs appeared stable during IVM. However, 70 transcripts underwent a significant differential regulation (by a factor of at least two). Their potential role in the context of oocyte maturation is discussed. Together they constitute a molecular signature of the degree of oocyte cytoplasmic maturation achieved in vitro.

Animals↗

PubMed2005

Low oxygen tension during in vitro maturation of porcine follicular oocytes improves parthenogenetic activation and subsequent development to the blastocyst stage.

To establish a reliable in vitro maturation system for activation and subsequent development as nuclear recipients for the effective production of pig clones, we assessed maturation, activation and parthenogenetic development in response to the following: (1) type of immature oocytes (cumulus-oocyte complexes (COCs) or parietal granulosa plus cumulus-oocyte complexes (GCOCs)); (2) oxygen (O(2)) tension (5 or 20%); and (3) maturation period (36-60 h). The rate of nuclear maturation to metaphase-II (M-II) in the GCOC group (73.0 +/- 3.1%) was higher than that in the COC group (P < 0.05, 60.6 +/- 3.5%), but the rates did not differ between the 5 and 20% O(2) tension groups. M-II rate increased (P < 0.05) to about 70% after 42 h and then remained constant until 60 h of culture. When oocytes were matured under 5% O(2) tension and stimulated, the rate of normal oocyte activation (a female pronucleus formation and emission of the second polar body) was higher (P < 0.05, 38.5 +/- 3.9%) than when oocytes were matured under 20% O(2) tension (24.5 +/- 3.9%). On the other hand, the rate of normal activation was not significantly different between the COC and GCOC groups, and the highest (P < 0.05) normal activation rate was obtained in oocytes cultured for 48 and 54 h (48.4 +/- 5.5% and 47.9 +/- 8.2%, respectively). When COC and GCOC matured for 48 h under 5 and 20% O(2) tension were stimulated and subsequently cultured in vitro for 6 days, the rate of blastocyst formation did not differ between the oocyte types nor between the O(2) tension groups. However, blastocyst quality, as measured by mean total cell number, was significantly higher in the 5% O(2) group (P < 0.05, 34.6 +/- 2.0 for COC; 33.8 +/- 1.8 for GCOC) compared with the 20% O(2) group (25.9 +/- 1.8 for COC; 27.0 +/- 2.0 for GCOC). In conclusion, low O(2) tension (5%) during in vitro maturation of porcine oocytes promoted their ability to be activated normally and improved the quality of parthenogenetic blastocysts developed in vitro in modified NCSU-37 solutions. This knowledge may be applicable for preparation of in vitro matured oocytes with good quality as recipient oocytes for generating pig clones.

Animals↗

PubMed2000

In vitro maturation of oocytes.

Only about 400 of the one million oocytes present at birth will be ovulated, while the rest will die by atresia. The ability to rescue oocytes destined to die and mature them in vitro would provide invaluable information about folliculogenesis and oocyte maturation, and could provide oocytes for infertile women. In vitro maturation (IVM) is challenging in the human because folliculogenesis is a lengthy process encompassing many complex cellular changes in the oocyte and its surrounding follicle cells. A few live births have resulted from the maturation and fertilization of immature human oocytes aspirated from small antral follicles. Furthermore, it is possible to grow primordial follicles to pre-antral stages in slices of ovarian tissue, and support antrum formation in isolated pre-antral follicles. However, we are still a considerable way from growing and maturing pre-antral follicles to pre-ovulatory stages in vitro. The importance of the follicular environment for producing a healthy and developmentally competent oocyte is illustrated by the oocyte's susceptibility to errors during meiosis. This counsels considerable caution in the development of IVM for clinical application.

Animals↗

PubMed1987

In vitro maturation of collagen fibrils modulates spreading, DNA synthesis, and collagenolysis of epidermal cells and fibroblasts.

Collagen fibrils were maturated in vitro by incubating them in a serum-containing culture medium at 37 degrees C for varied lengths of time. Epidermal cells and fibroblasts were cultured on these maturated collagen gels to see the effects of maturation on cellular morphology and physiology. The spreading and DNA synthesis of both types of cells on the maturated collagen gels were significantly enhanced compared to those on fresh gels. The maturation did not affect the cellular adhesiveness to the substrate. The secretion of collagenase by epidermal cells was suppressed on the maturated collagen gels, the extent of the suppression being related to the length of maturation of the gels. These maturation-related effects of collagen were also observed when collagen was incubated in the medium without serum, indicating that the effects are not due to deposition of serum proteins to collagen gels during maturation. Physical and chemical characterizations of the maturated collagen were performed: the mechanical strength of collagen gels increased in maturated collagen gels, the amounts of insoluble collagen increased with the maturation. These changes in the chemical and physical nature of the maturated collagen gel strongly suggested that there was an increase in intermolecular crosslinks during the process of maturation. These maturation-induced changes in collagen were marked when collagen gels were incubated in the presence of glucose, indicating that a glucose-protein reaction such as the Maillard reaction is involved in this phenomenon.

Animals↗

PubMed2003

Effects of myo-inositol on the in-vitro maturation and subsequent development of mouse oocytes.

BACKGROUND: The study aim was to assess whether the incorporation of myo-inositol (MI) into culture medium could improve oocyte maturation in vitro. METHODS AND RESULTS: We performed a controlled prospective study using female ICR strain mice superovulated with pregnant mare's serum gonadotrophins. Cumulus-enclosed germinal vesicle (GV) oocytes were randomly cultured in medium with or without MI supplementation. The kinetics of GV breakdown after 4 h of incubation was significantly higher in oocytes incubated with 30 mmol/l of MI than in controls (P < 0.001). Accordingly, this concentration of MI was used for subsequent experiments. The proportion of metaphase II oocytes achieved after 24 h of culture, their fertilization and cleavage rates were significantly higher in the MI-treated group (P < 0.01, P < 0.05, P < 0.05 respectively). This group also demonstrated significant improvement in postimplantation development after transferring the 2-cell embryos to pseudopregnant mice. Confocal microscopy revealed spontaneous intracellular Ca(2+) oscillations within competent GV oocytes and treatment with MI caused an earlier onset of these Ca(2+) signals. CONCLUSIONS: Our results suggest that MI may affect meiotic progression of mouse GV oocytes possibly by enhancing the intracellular Ca(2+) oscillations. Supplementation of MI in culture medium may be useful for human oocyte maturation.

Animals↗

PubMed1993

Parthenogenetic development of activated in vitro matured bovine oocytes.

Bovine oocytes matured in vitro for 26 hours were electrically stimulated 1) by a single pulse (Treatment A); 2) by 3 pulses 30 minutes apart (Treatment B); 3) by a single pulse followed by 5 minutes of incubation in the stimulation medium (Treatment C); or 4) by a single pulse at 27 hours of maturation (Treatment D). The oocytes were then cultured for up to 8 days to assess parthenogenetic activation and development. Each electrical stimulation consisted of a 60-mus square wave pulse of 2.5 or 3.6 kV/cm. Treatment A was less effective than the other treatments (P<0.05), activating 47 or 59% of oocytes at 2.5 or 3.6 kV/cm, respectively. However, there were no differences due to voltage nor among the other treatments, which activated 64 to 78% of the oocytes. The cleavage rate, 28 to 38%, was not affected by the activation treatment, but development to the 8-cell stage or beyond was greater after activation with the higher voltage. While the numbers of morulae or blastocysts resulting from any given treatment were too small to support meaningful statistical comparison, the results indicate that bovine parthenogenotes produced in vitro are capable of development to the blastocyst stage.

Journal Article↗

PubMed2000

Dynamic changes of cumulus-oocyte cell communication during in vitro maturation of porcine oocytes.

Oocyte maturation is a key issue of current animal biotechnology. This study was designed to examine the morphodynamics of the cumulus-oocyte association during oocyte maturation. Porcine cumulus-oocyte complexes were recovered from slaughterhouse ovaries; matured in vitro for 0, 24, 36, and 44 h; and evaluated by scanning electron microscopy either combined or not combined with the osmium-dimethyl sulfoxide-osmium maceration (ODO) method. The cytoskeleton distribution was also observed by fluorescence staining. Prior to maturation culture (0 h), the spherical cumulus cells were tightly clustered around the oocyte, with narrow intercellular spaces. They showed active secretion at 36 h and were fully expanded at 44 h of culture. The ODO methods revealed that the cumulus cells projected numerous long and thin transzonal projections at 0 h, but these were largely disconnected at 44 h. The outer surface of the zona pellucida showed a meshwork surface regardless of time of incubation, whereas the inner surface changed from a fine fibrous surface to a spongy surface that was coated with mucin. The vitelline surface changed from a sparse distribution of short microvilli (MV) to a dense distribution of well-developed MV. Fluorescence staining showed that the cumulus cell projections consisted mainly of microfilaments, which were abundant at the germinal vesicle and metaphase-I (M-I) stages (0-24 h) but which were decreased in number at the M-II stage (36-44 h). We conclude that the cumulus-oocyte transzonal projections became disconnected between the M-I and M-II stages as a result of cumulus expansion. The cumulus-cumulus communications, however, remained intact at these stages, although the biological functions of these communications were not clear.

Animals↗

PubMed1995

Microtubule rearrangement during in vitro maturation of pig oocytes. Effect of cycloheximide.

In freshly isolated fully grown pig oocytes at the germinal vesicle (GV) stage, the cytoplasmic microtubules are arranged in a meshwork. This microtubule arrangement is also maintained during the initial phases of meiotic maturation in vitro. A perinuclear array of microtubules is formed immediately before germinal vesicle breakdown (GVBD). Short-term treatment of oocytes with taxol when oocytes are at metaphase I stage induced formation of cytoplasmic asters. The oocyte cytoplasm is unable to respond to the taxol treatment at the earlier stages of meiotic maturation. In oocytes cultured with the proteosynthesis inhibitor cycloheximide, meiotic maturation is blocked. Condensation of chromatin occurs but the nuclear envelope is preserved and the microtubule arrangement is unchanged. A perinuclear array of microtubules does not appear and oocyte cytoplasm does not respond to short-term taxol treatment by the formation of cytoplasmic asters. We can conclude that the microtubule rearrangement and the acquisition of competence for tubulin assembly are blocked by cycloheximide and are thus dependent on de novo proteosynthesis.

Animals↗

PubMed2003

Time interval between FSH priming and aspiration of immature human oocytes for in-vitro maturation: a prospective randomized study.

This prospective randomized controlled study was performed to examine the influence of coasting for 2 days versus 3 days following a fixed daily dose of FSH for 3 days. The outcome was 2-fold. In the first experiment (n = 50 cycles), the incidence of apoptosis in granulosa cells was compared. In the second experiment (n = 28 cycles), the rates of maturation, fertilization, cleavage, pregnancy and implantation were compared. In addition, clinical pregnancy rate per aspiration was registered. Granulosa cells were collected from follicular aspirates and pooled for each patient. The APOPTAG Detection Kit was used for staining of the granulosa cells and detection of apoptosis. Oocytes were matured in vitro for 28-30 h before intracytoplasmic sperm injection. The incidence of apoptosis in granulosa cells did not differ between granulosa cells obtained after 2 days coasting (n = 25 cycles) compared with granulosa cells obtained after 3 days coasting (n = 25 cycles) (26.2 versus 26.2%). When oocytes obtained after coasting for 2 days (n = 12 cycles) were compared with oocytes obtained after coasting for 3 days (n = 16 cycles), no significant difference was found between rates of maturation (63 versus 65%), fertilization (60 versus 68%), cleavage (86 versus 92%) or implantation [5/12; 42 versus 1/12 (8%)]. A higher clinical pregnancy rate per aspiration [5/16 (31%) versus 1/12 (8%)] was obtained after coasting for 3 days compared with coasting for 2 days. The difference was not significant. This randomized study showed no difference in apoptosis of granulosa cells and no difference in developmental competence of oocytes obtained after coasting for 3 days compared with 2 days coasting.

Adult↗

PubMed2004

Chronological and ultrastructural changes in camel (Camelus dromedarius) oocytes during in vitro maturation.

Cumulus-oocyte complexes (COCs) were collected from non-pregnant camels at a local slaughterhouse by aspiration from antral follicles (2-6 mm). In Experiment I, camel COCs (n=304) were matured in vitro in Hams-F10, fixed at different time intervals (6, 12, 18, 24, 30, 36, 42, or 48 h) and stained with 1% aceto-orcein to assess nuclear changes in culture. A majority of the oocytes (81.5%) underwent germinal vesicle break down (GVBD) between 6 and 12h. Forty-eight percent of the oocytes were observed at the metaphase I (M I) stage by 18 h culture. The percentage of matured oocytes (M II stage) at 30 and 42 h were 66.5 and 71% respectively, which were significantly (p<0.05) different to that observed at 24 h (42.5%). In Experiment II, after different periods of culture (12, 24, 36, or 48 h), the COCs (n=26) were processed for transmission electron microscopy. Expansion of both the cumulus and corona radiate cells occurred between 12 and 24 h in the majority of oocytes concomitant with enlargement of the cumulus cell process endings (CCPEs) in the developed perivitelline space. After 12 h of culture disruption of the junctions between CCPEs and the oolemma was observed together with and breakdown of the GV. For 24-36 h of culture cortical granules had spread and aligned along the oolemma. Signs of degeneration in the cytoplasmic organelles of the oocytes were also observed from less than 36 h. After 48 h of culture, larger vesicles and lipid droplets had appeared in the central part of the oocytes and showed uneven distribution throughout the ooplasm. Predominantly non-penetrating CCPEs were also observed in four oocytes by 48 h. In conclusion, based on both light and electron microscopic evaluations, the optimal culture time for the development of competent Camelus dromedarius oocytes in vitro appears to be 30 h using Hams-F10 medium.

Animals↗

PubMed2006

Glucosamine supplementation during in vitro maturation inhibits subsequent embryo development: possible role of the hexosamine pathway as a regulator of developmental competence.

Glucose concentration during cumulus-oocyte complex (COC) maturation influences several functions, including progression of oocyte meiosis, oocyte developmental competence, and cumulus mucification. Glucosamine (GlcN) is an alternative hexose substrate, specifically metabolized through the hexosamine biosynthesis pathway, which provides the intermediates for extracellular matrix formation during cumulus cell mucification. The aim of this study was to determine the influence of GlcN on meiotic progression and oocyte developmental competence following in vitro maturation (IVM). The presence of GlcN during bovine IVM did not affect the completion of nuclear maturation and early cleavage, but severely perturbed blastocyst development. This effect was subsequently shown to be dose-dependent and was also observed for porcine oocytes matured in vitro. Hexosamine biosynthesis upregulation using GlcN supplementation is well known to increase O-linked glycosylation of many intracellular signaling molecules, the best-characterized being the phosphoinositol-3-kinase (PI3K) signaling pathway. We observed extensive O-linked glycosylation in bovine cumulus cells, but not oocytes, following IVM in either the presence or the absence of GlcN. Inhibition of O-linked glycosylation significantly reversed the effect of GlcN-induced reduction in developmental competence, but inhibition of PI3K signaling had no effect. Our data are the first to link hexosamine biosynthesis, involved in cumulus cell mucification, to oocyte developmental competence during in vitro maturation.

Animals↗

PubMed1999

Effect of different levels of intracellular cAMP on the in vitro maturation of cattle oocytes and their subsequent development following in vitro fertilization.

Serum, gonadotrophins, growth factors, and steroid hormones stimulate the in vitro maturation (IVM) of competent oocytes, acting, directly or indirectly, upon the adenylate cyclase pathway to produce the intracellular messenger, cAMP. The intracellular levels of cAMP in cattle cumulus-oocyte complexes (COC) were manipulated by adding to the collection and maturation media invasive adenylate cyclase (iAC), a toxin produced by the bacterium, Bordetella pertussis. High concentrations of iAC (1 or 5 microgram/ml) in the maturation medium inhibited the resumption of meiosis, while low concentrations (0.1 or 0.01 microgram/ml) resulted in high rates of maturation to the MII stage (92.6 +/- 2.5 and 98.5 +/- 1.4% respectively). The same low concentrations of iAC in the maturation medium resulted in rates of development to the blastocyst stage 8 days post insemination (30.1 +/- 4.2 and 45.1 +/- 3.9%, respectively), which were either not different, or significantly better, than those obtained after IVM in medium supplemented only with serum and gonadotrophins (36.1 +/- 2.9%). Finally, the addition of 0.1 microgram/ml iAC and 0.5 mM 3-isobutyl 1-methylxanthine (IBMX) in the collection medium significantly improved the blastocyst rate when IVM was performed in control medium or medium supplemented with 0.01 microgram/ml iAC (31.9 +/- 5.5 vs. 12.1 +/- 1.6 and 45.5 +/- 2.9 vs. 19.1 +/- 2.3% respectively). It is concluded that the maintenance of an optimal intracellular concentration of cAMP before and during IVM ensures a high developmental competence of bovine oocytes matured in medium without serum and hormones. Mol. Reprod. Dev. 54:86-91,1999.

1-Methyl-3-isobutylxanthine↗

PubMed2006

Multinucleation and cleavage of embryos derived from in vitro-matured oocytes.

In patients with polycystic ovary syndrome (PCOS), the proportion of optimal embryos-blastomere number and fragmentation rate-derived from in vitro-matured oocytes after the hCG priming protocol was higher (43.3%) than the proportion of optimal embryos derived from oocyte in vitro maturation with the FSH priming protocol (11.1%). The embryos derived from in vitro-matured oocytes after the hCG priming protocol also showed a lower incidence of multinucleated blastomeres. Pregnancies were recorded only in the hCG primed patients.

Adult↗

PubMed1980

Effect of striatal cells on in vitro maturation of mesencephalic dopaminergic neurones grown in serum-free conditions.

It is well documented that target cells can regulate the morphological and biochemical development of peripheral afferent neurones, but little is known about the existence of such regulatory mechanisms in the central nervous system. We therefore investigated previously the influence of striatal target cells on the maturation in vitro of nigrostriatal dopaminergic neurones, which survive in culture for more than 5 weeks, develop dense arborizations and both take up 3H-dopamine (DA) by a high-affinity specific process and synthesize 3H-DA from 3H-tyrosine. Furthermore, depolarization by potassium or veratridine stimulates the release of DA through a calcium-dependent mechanism and tetrodotoxin prevents the veratridine-evoked release of the transmitter. Both the number of 3H-DA uptake sites and the capacity for 3H-DA synthesis were at least doubled when the neurones were cultured with target cells from the striatum. To determine whether glial cells which proliferate in serum-complemented medium are partly responsible for the maturation of dopaminergic neurones and/or for the effect of striatal cells, we have now repeated the experiment using serum-free medium in which virtually pure neuronal populations can be obtained. The reduction in the number of glia did not affect either the maturation of dopaminergic cells alone, or the effect of striatal cells. Autoradiographic analysis of the number of dopaminergic cells strongly suggests that the stimulatory effect is related to increased capacities of 3H-DA uptake and synthesis per dopaminergic neurone.

Animals↗

PubMed2006

Effects of in vitro maturation of monkey oocytes on their developmental capacity.

The study of in vitro maturation (IVM) of rhesus monkey oocytes has important implications for biomedical research and human infertility treatment. In vitro-matured rhesus monkey oocytes show much less developmental potential than IVM oocytes of other species. Since about 1980 when rhesus monkey IVM, in vitro fertilization (IVF) and in vitro embryo culture (IVC) systems were established, numerous efforts have been made to improve the developmental competence of oocytes and to understand the mechanisms regulating oocyte maturation. This review describes recent progress in this area, particularly the effects of factors such as steroid hormones, energy substrates, amino acids, ovarian follicle status, maternal age and breeding season on the developmental competence, gene expression patterns and genome integrity of rhesus IVM oocytes.

Animals↗

PubMed2001

Mitochondrial distribution and adenosine triphosphate content of bovine oocytes before and after in vitro maturation: correlation with morphological criteria and developmental capacity after in vitro fertilization and culture.

In this study, we evaluated mitochondrial distribution and ATP content of individual bovine oocytes before and after in vitro maturation (IVM). Cumulus-oocyte complexes were classified according to morphological criteria: category 1, homogeneous oocyte cytoplasm, compact multilayered cumulus oophorus; category 2, cytoplasm with small inhomogeneous areas, more than five layers of compact cumulus; category 3, heterogeneous/vacuolated cytoplasm, three to five layers of cumulus including small areas of denuded zona pellucida; category 4, heterogeneous cytoplasm, completely or in great part denuded. In immature oocytes, staining with MitoTracker green revealed mitochondrial clumps in the periphery of the cytoplasm, with a strong homogenous signal in category 1 oocytes, a weaker staining in category 2 oocytes, allocation of mitochondria around vacuoles in category 3 oocytes, and poor staining of mitochondria in category 4 oocytes. After IVM, mitochondrial clumps were allocated more toward the center, became larger, and stained more intensive in category 1 and 2 oocytes. This was also true for category 3 oocytes; however, mitochondria maintained their perivacuolar distribution. No mitochondrial reorganization was seen for category 4 oocytes. Before IVM, the average ATP content of category 1 oocytes (1.8 pmol) tended to be higher than that of category 2 oocytes (1.6 pmol) and was significantly (P < 0.01) higher than in category 3 (1.4 pmol) and 4 oocytes (0.9 pmol). The IVM resulted in a significant (P < 0.01) increase in the average ATP content of all oocyte categories, with no difference between oocytes extruding versus nonextruding a polar body. After in vitro fertilization (IVF) and culture, significantly (P < 0.05) more category 1 and 2 than category 3 and 4 oocytes developed to the morula or blastocyst stage (determined 168 h after IVF). Total cell numbers of expanded blastocysts derived from category 1 and 2 oocytes were significantly (P < 0.05) higher than of those originating from category 3 and 4 oocytes. These data indicate that mitochondrial reorganization and ATP levels are different between morphologically good and poor oocytes and may be responsible for their different developmental capacity after IVF.

Adenosine Triphosphate↗

PubMed2002

Effect of cumulus cell removal of in vitro matured bovine oocytes prior to in vitro fertilization on subsequent cleavage rate.

The aim of this study is to identify the effect of cumulus cells removal prior to the in vitro fertilization of matured bovine oocytes on cleavage rate. Denuded, matured oocytes were fertilized in presence or absence of loose cumulus cells, cumulus cell conditioned IVF medium (CCCM), charcoal-treated CCCM and charcoal-treated CCCM supplemented with progesterone at a final concentration of 150 ng/ml. After 18 h of incubation with sperm, the presumptive embryos were cultured on a BRL monolayer and the percentage of cleaved embryos was evaluated on Day 4. Removal of cumulus cells prior to IVF significantly reduced the cleavage rate (25% for denuded oocytes versus 56% for cumulus-oocyte complexes (COCs)). The addition of loose cumulus cells partially restored the effect of denudation (cleavage rate: 37% for denuded oocytes supplemented with loose cumulus cells versus 27% for denuded oocytes and 58% for COCs). CCCM also had a positive effect on the cleavage rate of oocytes denuded prior to IVF (36% for denuded oocytes fertilized in CCCM versus 14% for denuded oocytes). Treating the CCCM with charcoal resulted in complete loss of its effect on cleavage rate (18% for denuded oocytes fertilized in charcoal-treated CCCM versus 34% for denuded oocytes fertilized in CCCM). The addition of progesterone to charcoal-treated CCCM partially restored the reduction of the cleavage rate caused by charcoal treatment (27% for denuded oocytes fertilized in charcoal-treated CCCM supplemented with progesterone versus 14% for denuded oocytes fertilized in charcoal-treated CCCM and 36% for denuded oocytes fertilized in CCCM). In conclusion, removal of cumulus cells prior to IVF adversely affects the cleavage rate through loss of a factor secreted by these cells. This factor probably is progesterone.

Animals↗