Relationship between cumulus cell apoptosis, progesterone production and porcine oocyte developmental competence: temporal effects of follicular fluid during IVM

The objective of the present study was to determine the temporal effects of sow follicular fluid (FF) in vitro on cumulus cell viability and function, as well as oocyte nuclear and cytoplasmic maturation. Cumulus–oocyte complexes (COCs) recovered from the ovaries of prepubertal pigs were matured in medium with (+FF) or without (–FF) follicular fluid for the first 22 h of IVM. At 22 h of IVM, each group of COCs was then transferred to medium with or without FF and matured for another 22 h, forming four treatment groups (–FF/–FF, –FF/+FF, +FF/–FF and +FF/+FF). The concentration of progesterone in spent IVM medium and the incidence of cumulus cell apoptosis in individual COCs were determined at 22 and 44 h of IVM. Cumulus expansion was also recorded at 44 h of IVM. Finally, the ability of oocytes to complete meiosis to the MII stage and form blastocysts after IVF and embryo culture was assessed. Maturation with FF for part or the whole of IVM increased cumulus expansion and progesterone production and decreased the incidence of cumulus cell apoptosis compared with the –FF/–FF group (P < 0.05). The changes were greatest for the +FF/+FF group and intermediate for the –FF/+FF and +FF/–FF groups. Regression analysis revealed a negative association between cumulus cell progesterone production and the incidence of cumulus cell apoptosis (P < 0.001). Meiotic maturation was enhanced when FF was present during the first half of IVM. Oocytes matured in the presence of FF during the first and/or second half of IVM displayed an increased ability to form blastocysts compared with the –FF/–FF group (P < 0.05). The extent of the increase was similar for all FF-supplemented groups. The results show that FF exerts several beneficial effects at different times during IVM and suggest that a major role of FF is to provide protection from oxidative stress. We propose that the incidence of cumulus cell apoptosis in COCs must be kept below a certain threshold to ensure adequate functionality, including steroidogenic activity, is maintained for the acquisition of oocyte developmental competence.

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342 DISTINCT EFFECTS OF FOLLICULAR FLUID ON CUMULUS CELL APOPTOSIS AND PORCINE OOCYTE DEVELOPMENTAL COMPETENCE

Reproduction Fertility and Development ◽

10.1071/rdv19n1ab342 ◽

2007 ◽

Vol 19 (1) ◽

pp. 286

Author(s):

C. G. Grupen ◽

T. S. Hussein ◽

S. J. Schulz ◽

D. T. Armstrong

Keyword(s):

Oxidative Stress ◽

Follicular Fluid ◽

Cell Apoptosis ◽

Polar Body ◽

Cumulus Cell ◽

Developmental Competence ◽

Potent Inducer ◽

Oocyte Developmental Competence ◽

Cytoplasmic Maturation

Supplementing medium with follicular fluid (FF) during in vitro maturation (IVM) enhances the developmental competence of porcine oocytes, indicating that factors present in FF are beneficial to cytoplasmic maturation. Previous findings suggest that porcine FF contains high levels of superoxide dismutase activity and exerts a beneficial effect on cytoplasmic maturation by protecting oocytes from oxidative stress (Tatemoto et al. 2004 Biol. Reprod. 71, 1150–1157). Since oxidative stress is a potent inducer of apoptosis, the aim of the present study was to examine the temporal effects of FF during IVM on cumulus cell apoptosis and oocyte developmental competence. Ovaries of prepubertal pigs were collected from a local abattoir and antral follicles, 3 to 7 mm in diameter, were aspirated. Cumulus–oocyte complexes (COCs) with at least 3 uniform layers of compact cumulus cells (CCs) were recovered, washed, and transferred to maturation medium (MM) with or without 25% FF. At 22 h of IVM, COCs from each group were washed and transferred to fresh MM with or without 25% FF, forming 4 groups: -FF/-FF, -FF/+FF, +FF/-FF, and +FF/+FF. Cohorts of COCs were TUNEL stained at 22 and 44 h of IVM using the In Situ Cell Death Detection kit (Roche Diagnostics, Castle Hill, NSW, Australia) according to the manufacturer's instructions, and apoptotic CCs were visualized using confocal microscopy. Oocytes denuded at 44 h, that had a polar body, were treated with ionomycin and 6-dimethylaminopurine to induce parthenogenetic development, and were cultured for 7 days in NCSU-23 medium at 38.5°C in 5&percnt; O2, 5&percnt; CO2, and 90&percnt; N2. Data were subjected to ANOVA and Tukey's post-hoc test. At 22 h of IVM, the presence of FF reduced the proportion of apoptotic CCs in COCs (2.1&percnt; vs. 4.6&percnt;). COCs matured with FF from 22 to 44 h of IVM had much lower proportions of apoptotic CCs (+FF/+FF: 0.9&percnt;; −FF/+FF: 2.6&percnt;) compared with those matured without FF (+FF/−FF: 10.3&percnt;; −FF/−FF: 17.8&percnt;). The rate of maturation to the metaphase-II stage was greater when oocytes were matured with FF from 0 to 22 h of IVM (−FF/−FF: 68.6&percnt;; −FF/+FF: 72.8&percnt;; +FF/−FF: 89.2&percnt;; +FF/+FF: 86.2&percnt;). Maturation without FF for the entire IVM interval reduced the proportion of activated oocytes that formed blastocysts compared with the other groups (−FF/−FF: 25.1&percnt;; −FF/+FF: 44.6&percnt;; +FF/−FF: 46.6&percnt;; +FF/+FF: 47.3&percnt;). Despite a 4-fold difference in the proportion of apoptotic CCs between COCs of the +FF/−FF and −FF/+FF groups, exposure to FF for the first or second half of IVM was as beneficial to oocyte developmental competence as exposure to FF for the entire IVM interval. This suggests that the protective effect of FF in reducing oxidative stress on oocytes during IVM is distinct from the effect on oocyte developmental competence.

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Oocyte Induction of EGF Responsiveness in Somatic Cells Is Associated With the Acquisition of Porcine Oocyte Developmental Competence

Endocrinology ◽

10.1210/en.2014-1884 ◽

2015 ◽

Vol 156 (6) ◽

pp. 2299-2312 ◽

Cited By ~ 27

Author(s):

Lesley J. Ritter ◽

Satoshi Sugimura ◽

Robert B. Gilchrist

Keyword(s):

Somatic Cell ◽

Oocyte Maturation ◽

Egf Receptor ◽

Somatic Cells ◽

Cumulus Cell ◽

Developmental Competence ◽

Cumulus Expansion ◽

Cell Functions ◽

Oocyte Developmental Competence

Abstract Oocytes progressively acquire the competence to support embryo development as oogenesis proceeds with ovarian folliculogenesis. The objectives of this study were to investigate oocyte-secreted factor (OSF) participation in the development of somatic cell epidermal growth factor (EGF) responsiveness associated with oocyte developmental competence. A well-established porcine model was employed using oocytes from small (<4 mm) vs medium sized (>4 mm) antral follicles, representing low vs moderate developmental competence, respectively. Cumulus-oocyte complexes (COCs) were treated in vitro with inducers of oocyte maturation, and cumulus cell functions and oocyte developmental competence were assessed. COCs from small follicles responded to FSH but, unlike COCs from larger follicles, were incapable of responding to EGF family growth factors known to mediate oocyte maturation in vivo, exhibiting perturbed cumulus expansion and expression of associated transcripts (HAS2 and TNFAIP6). Low and moderate competence COCs expressed equivalent levels of EGF receptor (EGFR) mRNA; however, the former had less total EGFR protein leading to failed activation of phospho-EGFR and phospho-ERK1/2, despite equivalent total ERK1/2 protein levels. Native OSFs from moderate, but not from low, competence oocytes established EGF responsiveness in low competence COCs. Four candidate recombinant OSFs failed to mimic the actions of native OSFs in regulating cumulus expansion. Treatment with OSFs and EGF enhanced oocyte competence but only of the low competence COCs. These data suggest that developmental acquisition by the oocyte of capacity to regulate EGF responsiveness in the oocyte's somatic cells is a major milestone in the oocyte's developmental program and contributes to coordinated oocyte and somatic cell development.

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327 OOCYTE-SECRETED FACTORS DIRECTLY AFFECT OOCYTE DEVELOPMENTAL COMPETENCE DURING IN VITRO MATURATION OF THE BOVINE CUMULUS - OOCYTE COMPLEX

Reproduction Fertility and Development ◽

10.1071/rdv18n2ab327 ◽

2006 ◽

Vol 18 (2) ◽

pp. 271 ◽

Cited By ~ 1

Author(s):

T. S. Hussein ◽

R. B. Gilchrist ◽

J. G. Thompson

Keyword(s):

In Vitro Maturation ◽

Cumulus Cell ◽

Blastocyst Stage ◽

Developmental Competence ◽

Bovine Oocyte ◽

Paracrine Factors ◽

Cell Functions ◽

Oocyte Developmental Competence ◽

Secreted Factors

Paracrine factors secreted by the oocyte (oocyte-secreted factors, OSFs) regulate a broad range of cumulus cell functions including proliferation, differentiation, and apoptosis. The capacity of oocytes to regulate their own microenvironment by OSFs may in turn contribute to oocyte developmental competence. The aim of this study was to determine if OSFs have a direct influence on bovine oocyte developmental competence during in vitro maturation (IVM). Cumulus-oocyte complexes (COCs) were obtained by aspiration of >3-mm follicles from abattoir-derived ovaries. IVM was conducted in Bovine VitroMat (Cook Australia, Eight Mile Plains, Brisbane, Australia) supplemented with 0.1 IU/mL rhFSH for 24 h under 6% CO2 in air at 38.5�C. In the first experiment, COCs were co-cultured with denuded oocytes (DOs, 5/COC in 10 �L) beginning at either 0 or 9-h of IVM. To generate the 9-h DO group, COCs were first cultured intact for 9-h and then denuded. In the second experiment, specific OSFs, recombinant bone morphogenetic protein-15 (BMP-15) and growth differentiation factor 9 (GDF-9), were prepared as partially purified supernatants of transfected 293H cells, and used as 10% v/v supplements in Bovine VitroMat. Treatments were: (1) control (no supplement), (2) BMP-15, (3) GDF-9, (4) BMP-15 and GDF-9, and (5) untransfected 293H control. Following maturation, in vitro production of embryos was performed using the Bovine Vitro system (Cook Australia) and blastocysts were examined on Day 8 for development. Developmental data were arcsine-transformed and analyzed by ANOVA, followed by Tukey's test. Cell numbers were analyzed by ANOVA. Co-culturing intact COCs with DOs from 0 or 9 h did not affect cleavage rate, but increased (P < 0.001) the proportion of cleaved embryos that reached the blastocyst stage post-insemination (50.6 � 1.9 and 61.3 � 1.9%, respectively), compared to COCs cultured alone (40.7 � 1.4%). Therefore, paracrine factors secreted by DOs increased the developmental competence of oocytes matured as COCs. OSFs also improved embryo quality, as co-culture of COCs with DOs (0 or 9 h) significantly increased total cell (156.1 � 1.3 and 159.1 � 1.3, respectively) and trophectoderm (105.7 � 1.3 and 109.8 � 0.4, respectively) numbers, compared to control COCs (total = 148 � 1.2, trophectoderm = 98.2 � 0.8, P < 0.001). BMP-15 alone or with GDF-9 also significantly (P < 0.001) increased the proportion of oocytes that reached the blastocyst stage post insemination (57.5 � 2.4% and 55.1 � 4.5%, respectively), compared to control (41.0 � 0.9%) and 293H-treated (27.1 � 3.1%) COCs. GDF-9 also increased blastocyst yield (49.5 � 3.9%) but not significantly. These results are the first to demonstrate that OSFs, and particularly BMP-15 and GDF-9, directly affect bovine oocyte developmental competence. These results have far-reaching implications for improving the efficiency of IVM in domestic species and human infertility treatment, and support the role of OSF production by oocytes as a diagnostic marker for developmental competence.

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205 CUMULUS CELL MORPHOLOGY BEFORE AND AFTER IN VITRO MATURATION AS AN INDICATOR OF PORCINE OOCYTE DEVELOPMENTAL COMPETENCE

Reproduction Fertility and Development ◽

10.1071/rdv22n1ab205 ◽

2010 ◽

Vol 22 (1) ◽

pp. 260

Author(s):

M. Bertoldo ◽

P. K. Holyoake ◽

G. Evans ◽

C. G. Grupen

Keyword(s):

Cell Morphology ◽

In Vitro Maturation ◽

Cumulus Cell ◽

Cumulus Cells ◽

Oocyte Quality ◽

Developmental Competence ◽

Oocyte Developmental Competence ◽

Before And After ◽

Follicle Size

Effective in vitro maturation (IVM) is essential for successful in vitro embryo production. The morphology of the cumulus investment before and after IVM may be a useful noninvasive indicator of oocyte quality. In pigs, oocyte developmental competence is reduced during the summer months. The aim of this study was to determine whether the morphology of cumulus-oocyte complexes (COC) before and after IVM are associated with oocyte quality, using COC collected from small and large follicles in summer and winter as models of poor and good oocyte quality. Ovaries were collected from sows slaughtered 4 days after weaning. The COC recovered from small (3-4 mm) and large (5-8 mm) antral follicles were morphologically graded and parthenogenetically activated following IVM during winter (n = 1419; 10 replicates) and summer (n = 2803; 10 replicates). Grade 1 and 2 COC had >2 layers of compact cumulus cells and a homogenous cytoplasm. Grade 3 COC were either partially or fully denuded, had a heterogeneous cytoplasm, or were vacuolated or dark in color. Grade 4 COC had expanded cumulus cells. Cumulus expansion was also assessed subsequent to IVM. The COC recorded as having a cumulus expansion index (CEI) of 1 had the poorest expansion with no detectable response to IVM, whereas those with a CEI of 4 had the greatest amount of expansion, including that of the corona radiata. Data were analyzed using a generalized linear mixed model in GenStat® (release 10, VSN International, Hemel Hempstead, UK). There was an effect of follicle size for Grade 1 COC, with COC from large follicles in both seasons yielding better quality COC (P < 0.05). The proportion of COC in Grade 2 was higher in small follicles during winter compared with large follicles, but there were no differences between follicle sizes during summer (P < 0.05). The proportion of COC with CEI 1 was highest in COC from small follicles during summer (P < 0.05). The proportion of COC from large follicles with CEI 2 was higher during summer compared with winter (P < 0.05). There were no seasonal or follicle size effects on COC with CEI 3 or 4 (P > 0.05). The proportion of oocytes that developed to blastocysts was greater in winter than in summer (39.06% ± 5.67 v. 22.27% ± 4.01; P < 0.05). Oocytes derived from large follicles had a greater ability to form blastocysts compared with those from small follicles (37.13% ± 5.65 v. 23.32% ± 4.56; P < 0.06). Morphological assessment of cumulus cells before and after IVM may be a useful tool to evaluate the effects of follicle size on oocyte developmental competence. However, the results of the present study indicate that cumulus cell morphology is not a good indicator of the effect of season on oocyte developmental competence.

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Cumulus Cell Expansion, Its Role in Oocyte Biology and Perspectives of Measurement: A Review

Scientia Agriculturae Bohemica ◽

10.1515/sab-2015-0002 ◽

2015 ◽

Vol 45 (4) ◽

pp. 212-225 ◽

Cited By ~ 4

Author(s):

J. Nevoral ◽

M. Orsák ◽

P. Klein ◽

J. Petr ◽

M. Dvořáková ◽

...

Keyword(s):

Extracellular Matrix ◽

Hyaluronic Acid ◽

High Performance ◽

Uv Light ◽

Cumulus Cell ◽

Developmental Competence ◽

Enzyme Linked Immunosorbent Assay ◽

Cumulus Expansion

Abstract Cumulus expansion of the cumulus-oocyte complex is necessary for meiotic maturation and acquiring developmental competence. Cumulus expansion is based on extracellular matrix synthesis by cumulus cells. Hyaluronic acid is the most abundant component of this extracellular matrix. Cumulus expansion takes place during meiotic oocyte maturation under in vivo and in vitro conditions. Quantification and measurement of cumulus expansion intensity is one possible method of determining oocyte quality and optimizing conditions for in vitro cultivation. Currently, subjective methods of expanded area and more exact cumulus expansion measurement by hyaluronic acid assessment are available. Among the methods of hyaluronic acid measurement is the use of radioactively labelled synthesis precursors. Alternatively, immunological and analytical methods, including enzyme-linked immunosorbent assay (ELISA), spectrophotometry, and high-performance liquid chromatography (HPLC) in UV light, could be utilized. The high sensitivity of these methods could provide a precise analysis of cumulus expansion without the use of radioisotopes. Therefore, the aim of this review is to summarize and compare available approaches of cumulus expansion measurement, respecting special biological features of expanded cumuli, and to suggest possible solutions for exact cumulus expansion analysis.

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Porcine follicular fluid derived from > 8 mm sized follicles improves oocyte maturation and embryo development during in vitro maturation of pigs

Zygote ◽

10.1017/s0967199420000398 ◽

2020 ◽

pp. 1-6

Author(s):

Ji-Eun Park ◽

Sang-Hee Lee ◽

Yong Hwangbo ◽

Choon-Keun Park

Keyword(s):

Embryonic Development ◽

Follicular Fluid ◽

In Vitro Maturation ◽

Developmental Competence ◽

Control Group ◽

Cumulus Expansion ◽

Treatment Groups ◽

Nuclear Maturation ◽

Cytoplasmic Maturation

Summary The aim of the present study was to investigate the effects of porcine follicular fluid (pFF) from large-sized (LFF; >8 mm in diameter) and medium-sized (MFF; 3–6 mm in diameter) follicles on the maturation and developmental competence of porcine oocytes. Cumulus–oocyte complexes (COCs) were collected from follicles 3–6 mm in diameter. The collected COCs were incubated for 22 h with LFF or MFF (in vitro maturation (IVM)-I stage) and were incubated subsequently for 22 h with LFF or MFF (IVM-II stage). Cumulus expansion was confirmed after the IVM-I stage and nuclear maturation was evaluated after the IVM-II stage. Intracellular glutathione (GSH) and reactive oxygen species (ROS) levels were measured and embryonic development was evaluated. Relative cumulus expansion and GSH levels were higher in the LFF group compared with in the MFF group after the IVM-I stage (P < 0.05). After the IVM-II stage, the numbers of oocytes in metaphase-II were increased in the LFF group and GSH content was higher in all of the LFF treatment groups compared with in the MFF treatment groups during both IVM stages (P < 0.05). ROS levels were reduced by LFF treatment regardless of IVM stage (P < 0.05). Blastocyst formation and the total numbers of cells in blastocysts were increased in all LFF treatment groups compared with the control group (P < 0.05). These results suggested that pFF from large follicles at the IVM stage could improve nucleic and cytoplasmic maturation status and further embryonic development through reducing ROS levels and enhancing responsiveness to gonadotropins.

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Endocrine-disrupting chemicals in human follicular fluid impair in vitro oocyte developmental competence

Human Reproduction ◽

10.1093/humrep/der448 ◽

2012 ◽

Vol 27 (4) ◽

pp. 1025-1033 ◽

Cited By ~ 52

Author(s):

Evi M.L. Petro ◽

Jo L.M.R. Leroy ◽

Adrian Covaci ◽

Erik Fransen ◽

Diane De Neubourg ◽

...

Keyword(s):

Follicular Fluid ◽

Endocrine Disrupting Chemicals ◽

Developmental Competence ◽

Human Follicular Fluid ◽

Oocyte Developmental Competence ◽

Endocrine Disrupting

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325RETINOID-DEPENDENT POLY(A) MRNA CONTENTS IN BOVINE OOCYTES PREMATURED AND/OR MATURED IN VITRO

Reproduction Fertility and Development ◽

10.1071/rdv16n1ab325 ◽

2004 ◽

Vol 16 (2) ◽

pp. 282

Author(s):

L.J. Royo ◽

A. Rodriguez ◽

A. Gutierrez-Adan ◽

C. Diez ◽

E. Moran ◽

...

Keyword(s):

Cumulus Cells ◽

Defined Medium ◽

Developmental Competence ◽

Mrna Levels ◽

Atp Production ◽

Beneficial Effects ◽

Oocyte Developmental Competence ◽

Grant Support ◽

Bovine Oocytes

Retinoic acid (RA) can induce cell differentiation and plays a role in controlling events within the cell cycle, but little is known of RA post-transcriptional modifications in the oocyte. Bovine oocyte and cumulus cells express most of RA receptors, and the presence of 9-cis-RA during in vitro prematuration and maturation (IVM) improves oocyte developmental competence (Duque et al., 2002 Hum. Reprod. 17, 2706–2714; Hidalgo et al., 2003 Reproduction 125, 409–416). This work analyzes the mRNA stability in bovine oocytes during in vitro prematuration and/or maturation. Cumulus-oocyte complexes (COCs) were cultured in defined medium with polyvinyl alcohol (DM). Those COCs undergoing prematuration were cultured for 24h in DM with 25μM roscovitine. For IVM, COCs were cultured in DM containing pFSH, LH and E2 for 24h, and some prematured COCs were then allowed to mature. Incubations were made at 39°C in 5% CO2 in air and high humidity. Within experiments, COCs were cultured with 5nM 9-cis-RA, in 1% ethanol (both as a vehicle and as an inhibitor of endogenous RA synthesis), 3% ethanol, 5% ethanol and untreated. Groups of 10 COCs per treatment were cultured, and oocytes detached from cumulus cells were analyzed. Poly(A) mRNA quantification was based on the pyrophosphorylation property of the DNA polymerase (Klenow). ATP production was measured by luminometric assay as a function of numbers of poly(A) tails. Data (4 replicates) were analyzed by ANOVA and Duncan’s test (v,x,y,zP<0.01; a,bP<0.05), and poly(A) mRNA (pg oocyte−1) was expressed as LSM±SE. After prematuration, poly(A) mRNA contents differed between 9-cis-RA (125.7±4.8x) and untreated (95.5±4.8y) oocytes, as compared to 1% ethanol (72.2±4.8z) and immature (71.5±4.8z) oocytes. After IVM, untreated oocytes (23.0±2.2v) showed the lowest poly(A) mRNA amount, and poly(A) mRNA in 9-cis-RA (36.2±2.2y) basically equalled that in 1% ethanol (35.2±2.2y), while 3% (44.5±2.2yz) and 5% ethanol (52.0±2.2z) increased poly(A) mRNA levels. All groups of matured oocytes showed poly(A) mRNA contents lower than in immature (71.5±4.8x). After prematuration+maturation, poly(A) mRNA values were 34.2±2.2v (untreated+untreated), 36.5±2.2v (9-cis-RA+untreated), 49.5±2.2xa (untreated+9-cis-RA), 41.0±2.2vxb (9-cis-RA+9-cis-RA) and 59.0±2.2y (untreated+1% ethanol). Levels of poly(A) mRNA from prematured+matured oocytes were again lower than in immature (71.5±4.8x). Our study shows that beneficial effects of RA on the oocyte developmental competence can be represented in part as a gain in the quality of mRNAs stored. Grant support: Spanish Ministry of Science and Technology (AGL-2002-01175).

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Temporal expression of cumulus cell marker genes during in vitro maturation and oocyte developmental competence

Journal of Assisted Reproduction and Genetics ◽

10.1007/s10815-017-0998-z ◽

2017 ◽

Vol 34 (11) ◽

pp. 1493-1500 ◽

Cited By ~ 12

Author(s):

Arindam Dhali ◽

Pradeep Krishna Javvaji ◽

Atul P. Kolte ◽

Joseph Rabinson Francis ◽

Sudhir C. Roy ◽

...

Keyword(s):

In Vitro Maturation ◽

Cumulus Cell ◽

Developmental Competence ◽

Marker Genes ◽

Cell Marker ◽

Temporal Expression ◽

Oocyte Developmental Competence

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Follicle-stimulating hormone mediates the consumption of serum-derived glycogen by bovine cumulus-oocyte complexes during in vitro maturation

Veterinary World ◽

10.14202/vetworld.2021.2512-2517 ◽

2021 ◽

pp. 2512-2517

Author(s):

Ludymila F. Cantanhêde ◽

Cristiane T. Santos-Silva ◽

Marcelo T. Moura ◽

José C. Ferreira-Silva ◽

Júnior M. B. Oliveira ◽

...

Keyword(s):

In Vitro Maturation ◽

Assisted Reproductive Technologies ◽

Follicle Stimulating Hormone ◽

Cumulus Cell ◽

Reproductive Technologies ◽

Developmental Competence ◽

Independent Manner ◽

Oocyte Developmental Competence ◽

Stimulating Hormone

Background and Aim: Oocyte in vitro maturation (IVM) is an appealing approach for several assisted reproductive technologies and dissecting oocyte maturation. Nonetheless, IVM leads to lower developmental competence and usually relies on undefined, serum-containing media. Therefore, biochemical profiling aimed to explore fluctuations in IVM media content during the acquisition of oocyte developmental competence. Materials and Methods: Bovine cumulus-oocyte complexes (COCs) underwent IVM in TCM199 medium with Earle's salts, supplemented with 2.0 mM L-glutamine, 10% fetal bovine serum, antibiotics, and 0.05 IU/mL porcine follicle-stimulating hormone (FSH+) or vehicle control (CTL) medium for 22 h. Results: FSH withdrawal (CTL) diminished several processes associated with the acquisition of oocyte developmental competence, such as reduced cumulus cell expansion, diminished estradiol synthesis (FSH+: 116.0±0.0 pg/mL vs. CTL: 97.6±18.0 pg/mL), and lower oocyte nuclear maturation rate (FSH+: 96.47% vs. CTL: 88.76%). Fresh media formulations (i.e., TCM199 with FSH or vehicle) were indistinguishable under biochemical profiling threshold conditions. Biochemical profiling showed similar total protein and lipid concentrations between groups. Further, total sugar concentrations diminished from fresh media to their post-IVM counterparts, albeit in an FSH-independent manner. Glycogen concentrations remained unaltered after IVM within CTL media, albeit were substantially lower after IVM under FSH+ conditions. Conclusion: FSH mediates the consumption of serum-derived glycogen by bovine COCs during IVM and implies that serum-free media should contain increased glucose concentrations to facilitate the acquisition of oocyte developmental competence.

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