Physiological factors underlying the formation of ovarian follicular fluid

21-Hydroxylase-derived steroids in follicles of nonobese women undergoing ovarian stimulation for in vitro fertilization (IVF) positively correlate with lipid content of luteinized granulosa cells (LGCs) as a source of cholesterol for steroid synthesis

CONTEXT

Mineralocorticoid synthesis by the nonhuman primate periovulatory follicle enhances luteinization. Whether a similar event occurs in women undergoing in vitro fertilization (IVF) is unknown.

OBJECTIVE

The objective of the study was to determine whether human luteinized granulosa cells (LGCs) produce mineralocorticoids derived from 21-hydroxylase activity and also express mRNA for 21-hydroxylase and the mineralocorticoid receptor.

DESIGN

This was a prospective cohort study.

SETTING

The study was conducted at an academic center.

PATIENTS

LGC lipid content and follicle fluid (FF) hormone analysis was performed on 27 nonobese IVF women. LGCs from six additional nonobese IVF women were used for gene expression studies.

INTERVENTION

At oocyte retrieval, FF was aspirated from the first follicle (≥16 mm in size) of each ovary and pooled LGCs were collected.

MAIN OUTCOME MEASURES

FF steroid analysis was performed by liquid chromatography-tandem mass spectrometry. LGCs were stained with lipid fluorescent dye BODIPY FL C16 to estimate lipid content by confocal microscopy as a cholesterol source for steroidogenesis in vivo. Quantitative real-time PCR was performed using LGCs to detect 21-hydroxylase and mineralocorticoid receptor mRNA expression. Pearson correlation coefficients determined associations between FF steroid levels and LGC lipid content.

RESULTS

FF levels of the 21-hydroxylase-derived steroids, 11-deoxycorticosterone [DOC, 39.97, median (13.94-63.02) ng/mL] and 11-deoxycortisol [11DOC, 2.07 (0.69-5.01) ng/mL], along with the 21-hydroxylase precursor 17-hydroxyprogesterone [1268.21 (493.26-3558.39) ng/mL], positively correlated with LGC lipid content (84 ± 43 fluorescent units/sample) (P ≤ .05, all steroids). 21-Hydroxylase and mineralocorticoid receptor mRNA expression was detected in LGCs.

CONCLUSIONS

Human LGCs likely synthesize 21-hydroxylase-derived mineralocorticoids from cholesterol-containing lipid in vivo to promote postovulatory luteinization via mineralocorticoid receptor-mediated events.

Multifactorial analysis of the follicular environment is predictive of oocyte morphology in cattle

Numerous attempts have been recently made in the search for a reliable, fast and noninvasive assay for selection of oocytes suitable for in vitro embryo production. Potential markers have been described in the follicle such as follicular fluid (FF) or cumulus cells (CCs). However, the reported findings are contradictory, which may reflect the complexity of metabolism of the ovarian follicle. In the present experiment, a data set from individual follicles of known diameter was obtained: cumulus-oocyte complex (COC) morphology, fatty acid composition and glucose concentration in FF as well as apoptotic index in CCs. The obtained data was statistically analyzed either separately (univariate analysis) or simultaneously (multivariate analysis) to examine its predictive value in morphology assessment of bovine COCs. Although the univariate analysis yielded a complex relation system of the selected parameters, no clear outcome could be established. In multivariate analysis, the concentration of the four fatty acids (C16:0, C16:1, C18:1cis9, C22:5n3) and Δ⁹-desaturase (16) as well as elongase activities were selected as covariates. This allowed prediction of the morphology of a COC with an accuracy of 72%, which is the most interesting finding of the experiment. The present study indicates that the multifactorial model comprising of selected parameters related to the follicle appeared more effective in predicting the morphology of a bovine COC, which may improve the effectiveness of in vitro production systems.

Exosomal and Non-Exosomal Transport of Extra-Cellular microRNAs in Follicular Fluid: Implications for Bovine Oocyte Developmental Competence

Cell-cell communication within the follicle involves many signaling molecules, and this process may be mediated by secretion and uptake of exosomes that contain several bioactive molecules including extra-cellular miRNAs. Follicular fluid and cells from individual follicles of cattle were grouped based on Brilliant Cresyl Blue (BCB) staining of the corresponding oocytes. Both Exoquick precipitation and differential ultracentrifugation were used to separate the exosome and non-exosomal fraction of follicular fluid. Following miRNA isolation from both fractions, the human miRCURY LNA™ Universal RT miRNA PCR array system was used to profile miRNA expression. This analysis found that miRNAs were present in both exosomal and non-exosomal fraction of bovine follicular fluid. We found 25 miRNAs differentially expressed (16 up and 9 down) in exosomes and 30 miRNAs differentially expressed (21 up and 9 down) in non-exosomal fraction of follicular fluid in comparison of BCB- versus BCB+ oocyte groups. Expression of selected miRNAs was detected in theca, granulosa and cumulus oocyte complex. To further explore the potential roles of these follicular fluid derived extra-cellular miRNAs, the potential target genes were predicted, and functional annotation and pathway analysis revealed most of these pathways are known regulators of follicular development and oocyte growth. In order to validate exosome mediated cell-cell communication within follicular microenvironment, we demonstrated uptake of exosomes and resulting increase of endogenous miRNA level and subsequent alteration of mRNA levels in follicular cells in vitro. This study demonstrates for the first time, the presence of exosome or non-exosome mediated transfer of miRNA in the bovine follicular fluid, and oocyte growth dependent variation in extra-cellular miRNA signatures in the follicular environment.

Metabolomic changes in follicular fluid induced by soy isoflavones administered to rats from weaning until sexual maturity

Female Wistar rats at 21 days of age were treated with one of three concentrations of soy isoflavones (SIF) (50, 100 or 200mg/kg body weight, orally, once per day) from weaning until sexual maturity (3 months) in order to evaluate the influence of SIF on ovarian follicle development. After treatment, the serum sex hormone levels and enumeration of ovarian follicles of the ovary were measured. The metabolic profile of follicular fluid was determined using HPLC-MS. Principal component analysis (PCA) and partial least-squares-discriminant analysis (PLS-DA) was used to identify differences in metabolites and reveal useful toxic biomarkers. The results indicated that modest doses of SIF affect ovarian follicle development, as demonstrated by decreased serum estradiol levels and increases in both ovarian follicle atresia and corpora lutea number in the ovary. SIF treatment-related metabolic alterations in follicular fluid were also found in the PCA and PLS-DA models. The 24 most significantly altered metabolites were identified, including primary sex hormones, amino acids, fatty acids and metabolites involved in energy metabolism. These findings may indicate that soy isoflavones affect ovarian follicle development by inducing metabolomic variations in the follicular fluid.

Liver condition affects bovine oocyte qualities by changing the characteristics of follicular fluid and plasma

The liver is an important organ that contributes to milk production in dairy cows. The aim of this study was to examine whether liver conditions affect the characteristics of blood plasma and follicular fluid (FF) and whether supplementing in vitro maturation medium with FF from either cows with damaged livers (DL) or those with healthy livers (HL) affects oocyte developmental competence. Biochemical characteristics of FF were significantly correlated with those in plasma. As such, the characteristics of both plasma and FF were similarly affected by liver conditions in that the concentrations of total protein and inorganic phosphorus were higher for the DL cow group than for the HL cow group, whereas the concentrations of albumin, lactate dehydrogenase and calcium were lower for DL cows than for HL cows. In addition, supplementing the medium with DL-FF retarded the progression of the nuclear maturation of oocytes collected from the HL cows. On culturing oocytes in maturation medium containing HL-FF, DL-FF or foetal calf serum, the highest developmental rate to the blastocyst stage was observed in the HL-FF group, while the lowest developmental ratio was observed in the DL-FF group. The growth factor array of the FFs revealed that 10 growth factors were significantly downregulated in the DL-FF compared with those in HL-FF. In conclusion, the characteristics of plasma and FF are affected by liver conditions in a similar way. Concentrations of several growth factors were low in DL-FF, as was the ability of DL-FF to support oocyte maturation compared with that of HL-FF.

The blood-follicle barrier (BFB) in disease and in ovarian function

The blood-follicle barrier (BFB) is one of the blood-tissue barriers in mammalian body found in developing follicles in the ovary. The BFB, besides the tight junction (TJ)-permeability barrier of the endothelial cells in the microvessels that surround the developing follicle, is constituted and contributed significantly by the basement membrane of the developing follicle which alters its composition rapidly during follicle development. While the concept of the BFB and its ultrastructure were described more than six decades ago, fewer than 20 reports are found in the literature that were dedicated to investigate the biology, regulation, and function of the BFB either in health or in disease. Furthermore, detailed analysis of the adhesion protein complexes and the regulation of the junction dynamics at the BFB are still missing in the literature. The goal of this short chapter is to provide an update on this important blood-tissue barrier, it is obvious that future investigation is much needed in the field to understand this ultrastructure better in order to treat and better ovarian disorders including ovarian cancer.

The consequences of metabolic changes in high-yielding dairy cows on oocyte and embryo quality

Unsatisfactory reproductive performance in dairy cows, such as reduced conception rates, in addition to an increased incidence of early embryonic mortality, is reported worldwide and has been associated with a period of negative energy balance (NEB) early post partum. Typically, NEB is associated with biochemical changes such as high non-esterified fatty acid (NEFA), high β-hydroxybutyrate (β-OHB) and low glucose concentrations. The concentrations of these and other metabolites in the follicular fluid (FF) of high-yielding dairy cows during NEB were determined and extensively analyzed, and then were replicated in in vitro maturation models to investigate their effect on oocyte quality. The results showed that typical metabolic changes during NEB are well reflected in the FF of the dominant follicle. However, the oocyte seems to be relatively isolated from extremely elevated NEFA or very low glucose concentrations in the blood. Nevertheless, the in vitro maturation models revealed that NEB-associated high NEFA and low glucose levels in the FF are indeed toxic to the oocyte, resulting in deficient oocyte maturation and developmental competence. Induced apoptosis and necrosis in the cumulus cells was particularly obvious. Furthermore, maturation in saturated free fatty acid-rich media had a carry-over effect on embryo quality, leading to reduced cryotolerance of day 7 embryos. Only β-OHB showed an additive toxic effect in moderately hypoglycemic maturation conditions. These in vitro maturation models, based on in vivo observations, suggest that a period of NEB may hamper the fertility of high-yielding dairy cows through increased NEFA and decreased glucose concentrations in the FF directly affecting oocyte quality. In addition to oocyte quality, these results also demonstrate that embryo quality is reduced following an NEB episode. This important observation may be linked to the typical diet provided to stimulate milk yield, or to physiological adaptations sustaining the high milk production. Research into this phenomenon is ongoing.

Bovine dominant follicular fluid promotes the in vitro development of goat preantral follicles

The aim of this study was to evaluate the effect of follicular fluid collected from bovine dominant follicles (bFF) on the in vitro development of goat preantral follicles and determine the best time to add this supplement to the culture medium. The preantral follicles were isolated and randomly distributed into four treatments in absence (control) or presence of 10% of bFF added on Days 0 (FF0-18), 6 (FF6-18) or 12 (FF12-18) of culture onwards. After 18 days, follicular development was assessed based on follicular survival, antral cavity formation, increased follicular diameter as well as fully grown oocyte (>110 μm) viability and meiosis resumption. The oocytes from the cultured follicles were in vitro-matured and processed for fluorescence or ultrastructural analysis. The results showed that on Day 18 the treatment FF0-18 had a significantly higher (P<0.05) survival than control and FF12-18, but not FF6-18. The addition of bFF at the beginning of culture (FF0-18 and FF6-18) promoted a high percentage of follicular growth, meiosis resumption and early antrum formation. Moreover, this study described for the first time the ultrastructural analysis of caprine oocytes grown in vitro. This evaluation revealed that in the presence of bFF on (FF0-18) the in vitro-grown oocytes presented normal organelle distribution and well-defined, intact plasma and nuclear membranes. In conclusion, bFF originating from dominant follicles maintain the survival and promote the in vitro growth of goat preantral follicles when added at the beginning of culture.

Proteomic analysis of mare follicular fluid during late follicle development

Background

Follicular fluid accumulates into the antrum of follicle from the early stage of follicle development. Studies on its components may contribute to a better understanding of the mechanisms underlying follicular development and oocyte quality. With this objective, we performed a proteomic analysis of mare follicular fluid. First, we hypothesized that proteins in follicular fluid may differ from those in the serum, and also may change during follicle development. Second, we used four different approaches of Immunodepletion and one enrichment method, in order to overcome the masking effect of high-abundance proteins present in the follicular fluid, and to identify those present in lower abundance. Finally, we compared our results with previous studies performed in mono-ovulant (human) and poly-ovulant (porcine and canine) species in an attempt to identify common and/or species-specific proteins.

Methods

Follicular fluid samples were collected from ovaries at three different stages of follicle development (early dominant, late dominant and preovulatory). Blood samples were also collected at each time. The proteomic analysis was carried out on crude, depleted and enriched follicular fluid by 2D-PAGE, 1D-PAGE and mass spectrometry.

Results

Total of 459 protein spots were visualized by 2D-PAGE of crude mare follicular fluid, with no difference among the three physiological stages. Thirty proteins were observed as differentially expressed between serum and follicular fluid. Enrichment method was found to be the most powerful method for detection and identification of low-abundance proteins from follicular fluid. Actually, we were able to identify 18 proteins in the crude follicular fluid, and as many as 113 in the enriched follicular fluid. Inhibins and a few other proteins involved in reproduction could only be identified after enrichment of follicular fluid, demonstrating the power of the method used. The comparison of proteins found in mare follicular fluid with proteins previously identified in human, porcine and canine follicular fluids, led to the identification of 12 common proteins and of several species-specific proteins.

Conclusions

This study provides the first description of mare follicular fluid proteome during the late follicle development stages. We identified several proteins from crude, depleted and enriched follicular fluid. Our results demonstrate that the enrichment method, combined with 2D-PAGE and mass spectrometry, can be successfully used to visualize and further identify the low-abundance proteins in the follicular fluid.

The water permeability channels aquaporins 1-4 are differentially expressed in granulosa and theca cells of the preovulatory follicle during precise stages of human ovulation

CONTEXT

Changes in vascular permeability and expansion of the fluid-filled antrum are major events in the LH-induced ovulatory process.

OBJECTIVES

Our objective was to investigate the presence and expression levels of aquaporins (AQPs) in the granulosa and theca cell compartments of the follicle during defined phases of human ovulation.

DESIGN AND SETTING

We conducted a prospective experimental study at the Department of Obstetrics and Gynaecology at a university hospital.

PARTICIPANTS

Twenty-eight women underwent laparoscopic sterilization and at the same time follicle retrieval at four periovulatory phases.

MAIN OUTCOME MEASURES

mRNA levels of AQP1-4 were measured in separated granulosa and theca cells from preovulatory phase, early ovulatory (EO) phase, late ovulatory phase, and postovulatory phase. Immunohistochemistry was done for AQP1-4 in intact human follicles.

RESULTS

All four AQPs were expressed in both the theca and granulosa cells during ovulation. In granulosa cells, AQP1 levels increased in the late ovulatory and postovulatory phases. Expression of AQP2-3 followed a similar pattern with a marked increase in the EO phase, whereas AQP4 levels decreased from preovulatory to the EO phase. The presence of AQP1-4 in the human follicle was verified by immunohistochemistry.

CONCLUSIONS

The results show for the first time the presence of AQP1-4 in human follicles during ovulation. The marked early rise in expression of AQP2 and AQP3 suggests a role during the process leading to follicular rupture, and the late rise of AQP1 suggests a role in corpus luteum formation.

Metabolite concentrations in follicular fluid may explain differences in fertility between heifers and lactating cows

There has been a marked decline in the fertility of dairy cows over the past decades, and metabolomic analysis offers a potential to investigate the underlying causes. Metabolite composition of the follicular fluid, which presents the intrafollicular environment, may be an important factor affecting oocyte maturation and subsequent early embryo development. The aim of the present study was to investigate the metabolic differences between follicular fluid from the dominant follicle of lactating cows and heifers using gas chromatography mass spectrometry (GC-MS)-based metabolomics. Follicular fluid and serum were collected from cows and heifers over three phases of follicle development: newly selected dominant follicles, preovulatory follicles prior to oestrus and post-LH surge follicles. Analysis of the fatty acids revealed that there were 24 fatty acids and 9 aqueous metabolites significantly different between cows and heifers. Of particular interest were the higher concentrations of saturated fatty acids (palmitic acid, P=0.001; stearic acid, P=0.005) in follicular fluid from cows and higher docosahexaenoic acid levels (P=0.022) in follicular fluid from heifers. Analysis of the metabolite composition of serum revealed that follicular fluid had a unique lipid composition. The higher concentrations of detrimental saturated fatty in cows will have a negative impact on oocyte maturation and early embryo development. Overall, the results suggest that the follicle microenvironment in cows potentially places their oocytes at a developmental disadvantage compared with heifers, and that this may contribute to well-characterised differences in fertility.

Formation of the ovarian follicular antrum and follicular fluid

The formation of the follicular antrum and follicular fluid has received scant attention from researchers, yet both are important processes in follicular development. The central hypothesis on follicular fluid formation suggests that production by granulosa cells of hyaluronan and the chondroitin sulfate proteoglycan versican generates an osmotic gradient. This gradient draws in fluid derived from the thecal vasculature. Inter-alpha-trypsin inhibitor is also present in follicular fluid at least in species with large follicles, and inter-alpha-trypsin inhibitor and versican could additionally bind or cross-link with hyaluronan, resulting in the retention of these molecules within the follicular antrum. Barriers to the movement of fluid across the membrana granulosa are apparently minimal, as even relatively large serum proteins are present in follicular fluid. Despite the relative permeability of the follicular wall, aquaporins are present in granulosa cells and could be actively involved in the transport of water into the follicle. The formation of an antrum also requires movement of granulosa cells relative to each other to allow the fluid to accumulate. This presumably involves remodeling of cell-cell junctions and in species with small follicles may involve death of centrally located granulosa cells. Remodeling of the stroma and thecal layers also accompanies growth and expansion of the antrum and presumably involves similar processes that accompany growth of other glands.

The biology and technology of follicular oocyte development in vitro

Fully mature oocytes are the rarest cells in the body. A premenopausal woman produces only one during each menstrual cycle and that survives for just a single day. Ovarian productivity is parsimonious in order that the ovulation rate matches the optimal capacity of the uterus for carrying conceptuses to full-term. But, in this new era of assisted reproductive medicine, there are many applications for which spare oocytes are needed (Table 1), and it is desirable to obtain more cells than are routinely available during superstimulated cycles. Since the great majority of ovarian oocytes undergo atresia (> 99.9%), the possibility of tapping the store of immature oocytes before they degenerate and maturing them in vitro is very attractive.

Permselectivity of blood follicle barriers in mouse ovaries of the mifepristone-induced polycystic ovary model revealed by in vivo cryotechnique

Despite the potential association of polycystic ovary (PCO) syndrome with hemodynamic changes, follicular microenvironment and the involvement of blood follicle barriers (BFB), a histopathological examination has been hampered by artifacts caused by conventional preparation methods. In this study, mouse ovaries of a mifepristone-induced PCO model were morphologically and immunohistochemically examined byin vivocryotechnique (IVCT), which prevents those technical artifacts. Ovarian specimens of PCO model mice were prepared by IVCT or the conventional perfusion fixation after s.c. injection of mifepristone. Their histology and immunolocalization of plasma proteins, including albumin (molecular mass, 69 kDa), immunoglobulin G (IgG, 150 kDa), inter-α-trypsin inhibitor (ITI, 220 kDa), fibrinogen (340 kDa), and IgM (900 kDa), were examined. In the PCO model, enlarged blood vessels with abundant blood flow were observed in addition to cystic follicles with degenerative membrana granulosa. The immunolocalization of albumin and IgM in the PCO model were similar to those in normal mice. Albumin immunolocalized in the blood vessels, interstitium or follicles, and IgM was mostly restricted within the blood vessels. In contrast, immunolocalization of IgG, ITI, and fibrinogen changed in the PCO model. Both IgG and ITI were clearly blocked by follicular basement membranes, and hardly observed in the membrana granulosa, though fibrinogen was mostly observed within blood vessels. These findings suggest that increased blood flow and enhanced selectivity of molecular permeation through the BFB are prominent features in the PCO ovaries, and changes in hemodynamic conditions and permselectivity of BFB are involved in the pathogenesis and pathophysiology of PCO syndrome.

Osmolarity at early culture stage affects development and expression of apoptosis related genes (Bax-alpha and Bcl-xl) in pre-implantation porcine NT embryos

This study examined whether high osmolarity of culture medium at the early culture stage affects development and expression of apoptosis related genes (Bax-alpha and Bcl-xl) of porcine nuclear transfer (NT) and in vitro fertilization (IVF) embryos. NT and IVF embryos were divided into three groups and the basic medium was PZM-3 (260-270 mOsmol, control group). The control group of embryos was cultured in PZM-3 for whole culture period. Other two groups of embryos were cultured in a modified PZM-3 with 0.05 M sucrose (300-320 mOsmol, sucrose group) or increased NaCl to 138 mM (300-320 mOsmol, NaCl group) for the first 2 days, and then cultured in PZM-3 for 4 days. NT embryos cultured in NaCl group showed a significantly higher developmental rate to the blastocyst stage with a decreased apoptosis rate compared to the control (P < 0.05). There was no difference in blastocyst formation and apoptosis incidence among the three culture treatments for IVF-derived embryos. Bax-alpha mRNA expression was significantly higher in the control than sucrose or NaCl group for both NT and IVF embryos (P < 0.05). Moreover, the relative abundance of Bax-alpha/Bcl-xl was higher in the control than the treatment groups. These results indicate that the higher osmolarity at the early embryonic stage of porcine NT and IVF embryos can improve the in vitro development with reduced apoptosis through regulating the Bax-alpha/Bcl-xl gene expression.

Theoretical investigation into the dissolved oxygen levels in follicular fluid of the developing human follicle using mathematical modelling

Oxygen levels in the follicle are likely to be critical to follicle development. However, a quantitative description of oxygen levels in the follicle is lacking. Mathematical modelling was used to predict the dissolved oxygen levels in the follicular fluid of the developing human follicle. The model predictions showed that follicular fluid dissolved oxygen levels are highly variable among follicles, due to the unique geometry of individual follicles. More generally, predictions showed that oxygen levels in follicular fluid increase rapidly during the initial early antral stages of follicle growth before peaking in the later early antral phase. Follicular fluid dissolved oxygen levels then decline through to the beginning of the pre-ovulatory phase, from which they increase through to ovulation. Based on the best available parameter estimates, the model predictions suggest that the mean dissolved oxygen levels in human follicular fluid during the late antral and pre-ovulatory phases range between 11 and 51 mmHg (~1.5–6.7 vol%). These predictions suggest that the human ovarian follicle is a low-oxygen environment that is often challenged by hypoxia, and are in agreement with only some published data on follicular fluid oxygen levels. Predictions are discussed in relation to follicle health and oocyte culture.

Proteome analysis of human follicular fluid

We used proteomic approach to analyze the protein profile of human follicular fluid (HFF) obtained from 25 normo-ovulatory women undergoing assisted reproduction techniques due to a male infertility factor. In all HFF samples analyzed we found 695 common spots distributed in the 3 to 10 pH range and in the 10-200 kDa range. Only 625 of these spots were also present in the plasma. We used MALDI-TOF-MS analysis to unequivocally assign 183 HFF/plasma matched spots and 27 HFF/plasma unmatched spots. A large number of acute-phase proteins, including transferrin, ceruloplasmin, afamin, hemopexin, haptoglobin and plasma amyloid protein, were identified in HFF in relatively high concentration supporting the hypothesis that mammalian ovulation can be compared to an inflammatory event. We also identified several important antioxidant enzymes; i.e., catalase, superoxide dismutase, glutathione transferase, paraoxonase, heat shock protein 27 and protein disulfide isomerase. This indicates that during maturation the human follicle is well protected against toxic injury due to oxidative stress.

Fluctuations in bovine ovarian follicular fluid composition throughout the oestrous cycle

Bovine oocyte maturation in vitro frequently results in abnormal cytoplasmic maturation and failure to acquire developmental competence. This is, in part, likely to be due to the non-physiological nutritional milieu to which oocytes are exposed. Improvements in oocyte developmental potential may be achieved by modelling nutrient profiles on those of preovulatory follicular fluid (FF). However, little is known about fluctuations in FF nutrient levels according to follicle dominance and oestrous cyclicity. This study therefore characterised the carbohydrate and amino acid profile of FF according to these parameters, and compared preovulatory FF composition with that of maturation medium. Carbohydrate concentrations (n = 121) were determined enzymatically whilst amino acid profiles (n = 40) were determined by reverse-phase HPLC. Pyruvate and glucose concentrations were unaffected by follicle dominance, whereas Stage III-IV lactate profiles were higher in non-dominant FF (P < 0.01). While most dominant FF amino acid concentrations were affected by oestrous stage, only glutamate, alanine, leucine and lysine levels fluctuated in non-dominant FF. Glucose and lactate concentrations were significantly negatively correlated, whereas most amino acids were significantly positively correlated with each other. Maturation medium had higher pyruvate and lower lactate concentrations than preovulatory FF (P < 0.001), whereas glucose level was similar. All amino acid levels (except histidine, taurine, alanine and tryptophan) differed significantly between maturation medium and preovulatory FF. These data indicated that FF composition varies throughout the oestrous cycle. Preovulatory FF nutrient profile differed from that of maturation medium, perhaps accounting for the poor developmental competence of in vitro matured oocytes. These data may contribute to the formulation of a nutritionally more physiological maturation medium.

Metabolite and ionic composition of follicular fluid from different-sized follicles and their relationship to serum concentrations in dairy cows

Metabolic changes in blood serum may be reflected in the biochemical composition of follicular fluid and could indirectly influence oocyte quality. The purpose of this study was to examine the biochemical composition of follicular fluid harvested from different-sized follicles and its relationship with that of blood serum in dairy cattle. Following slaughter, blood samples were collected from dairy cows n=30 and follicular fluid aspirated from three size classes of non-atretic follicles (<4 mm, 6-8 mm and >10 mm diameter). Samples remained independent between cows and between size classes within cows. Serum and follicular fluid samples were assayed using commercial clinical and photometric chemistry assays for ions (sodium, potassium and chloride) and metabolites (glucose, beta-hydroxybutyrate (beta-OHB), lactate, urea, total protein, triglycerides, non-esterified fatty acids (NEFA) and total cholesterol). Results showed that follicular fluid concentrations of glucose, beta-OHB and total cholesterol increased from small to large follicles and decreased for potassium, chloride, lactate, urea and triglycerides. There was a significant concentration gradient for all variables between their levels in serum and follicular fluid (P<0.05). Significant correlations were observed for chloride (r=0.40), glucose (r=0.56), beta-OHB (r=0.85), urea (r=0.95) and total protein (r=0.60) for all three follicle size classes and for triglycerides (r=0.43), NEFA (r=0.50) and total cholesterol (r=0.42) for large follicles (P<0.05). The results from the present study suggest that the oocyte and the granulosa cells of dairy cows grow and mature in a biochemical environment that changes from small to large follicles. Furthermore, the significant correlation between the composition of serum and follicular fluid for the above-mentioned metabolites suggests that metabolic changes in serum levels will be reflected in the follicular fluid and, therefore, may affect the quality of both the oocyte and the granulosa cells.

Divalent cation levels in serum and preovulatory follicular fluid of women undergoing in vitro fertilization embryo transfer

In this controlled clinical study, we determined the serum and follicular fluid concentrations of the biologically active fractions of magnesium (Mg) and calcium (Ca) in 39 women undergoing controlled ovarian stimulation (COH) for in vitro fertilization (IVF) embryo transfer (ET). Serum levels of ionized Ca (Ca2+) and ionized Mg (Mg2+) were measured during day 3 of the IVF cycle, on the day of ovum pickup and 12 days following ET. Follicular fluid levels were measured on the day of ovum pickup. Serum levels of Mg2+ decreased and Ca2+ levels increased during the IVF cycle. Mg levels were significantly higher in follicular fluid than in serum. Ca2+ and Mg2+ may play a role in the preovulatory follicle, a possibility that warrants further study.

Water permeability of an ovarian antral follicle is predominantly transcellular and mediated by aquaporins

Ovarian folliculogenesis is characterized, in part, by the formation and expansion of the fluid-filled antrum. Development of this cavity requires water influx, which may occur by transcellular or pericellular transport mechanisms. To assess the contribution of these mechanisms to the water permeability of an antral follicle, the rate of (3)H(2)O and (14)C-inulin (a complex sugar restricted to the extracellular compartment) uptake into isolated follicles was determined. The rate of H(2)O movement was 3.5-fold greater than that of inulin, suggesting that water enters a follicle primarily by transcellular pathways. Preincubation of the follicles with 50 microM HgCl(2) [a nonspecific aquaporin (Aqp) inhibitor] decreased H(2)O movement to levels seen with inulin, indicating that transcellular water movement is mediated through Aqp. To demonstrate the functional presence of Aqp in granulosa cells, we show that swelling in response to a hypotonic insult is attenuated by preincubation with 50 microM HgCl(2). Flow cytometry demonstrated the presence of Aqps-7, -8, and -9, thus identifying candidate Aqp potentially mediating water movement into antral follicles. These results suggest that water permeability of antral follicles occurs primarily through transcellular mechanisms, which may be mediated by Aqps -7, -8, and/or -9 in granulosa cells.

Effects of hepatitis C virus on the apoptosis percentage of granulosa cells in vivo in women undergoing IVF: preliminary results

BACKGROUND

The aim of this study was to investigate the relationship between the apoptosis percentage of human luteinized granulosa cells (GC) and the presence of hepatitis C virus (HCV) in follicular fluid (FF).

METHODS

GC were isolated from FF of 12 women undergoing 12 IVF cycles: six were HCV+ with active viral replication and six HCV- serving as controls. No male partner was HCV+. HCV detection and quantification were assessed by reverse transcriptase-polymerase chain reaction in serum, FF and embryo-incubation medium. GC were analysed by flow cytometry after propidium iodide staining to measure the percentages of apoptotic GC. Routine IVF parameters were tabulated.

RESULTS

Mean +/- standard deviation (SD) serum and FF HCV viral loads were 3.58 +/- 4.25 x 10(6) and 0.14 +/- 0.10 x 10(6) IU/ml respectively. Mean percentages of apoptotic GC from HCV+ and HCV- women were 3.08 +/- 1.14 and 3.14 +/- 1.40% respectively. No statistically significant difference was found between these two groups concerning GC apoptosis and when we compared all IVF parameters. No HCV RNA was detected in embryo incubation media after 2 days of culture.

CONCLUSIONS

Comparing GC apoptosis percentages and usual IVF parameters in the HCV+ group versus the HCV- group, our preliminary study shows that active chronic HCV infection does not affect follicle development and IVF outcome in HCV+ women undergoing IVF. Furthermore, the risk of newborns becoming HCV-infected might not be increased by assisted reproductive technologies when performed in couples in which women are HCV+ and men HCV-.

Follicular fluid responds endothermically to aqueous dilution

BACKGROUND

Studies suggest that ovarian follicles are cooler than their surrounding tissues. The mechanism of this remarkable phenomenon is unclear. We postulate that endothermic reactions accompany the growth-associated hydration of follicular fluid.

METHODS

We performed two types of experiment, using human and animal follicular fluids. In the first, saline (50 microl) was injected into follicular fluid (500 microl) held in an equilibrated incubator, with monitoring of sample temperature. In the second, an adiabatic microcalorimeter recorded thermal shifts after injection of buffer (10 microl) into previously dialysed samples (1.4 ml). The relevance of changes observed was assessed by mathematical modelling.

RESULTS

In the incubator study, 9/17 bovine and 6/12 human fluids showed a temperature fall (0.05-0.2 degrees C). Cooling was delayed by up to 2 min but sustained for 7-25 min. Remaining fluids showed no change. In the microcalorimeter, 4/9 human, 4/6 bovine, 5/5 porcine and 1/4 equine samples showed an endothermic response. Remaining samples showed either no response (bovine) or exothermy (human, equine). Pre-concentration of human follicular fluid amplified the endothermy or reversed the exothermy. Modelling indicated that the incubator-type response was of appropriate magnitude to explain follicular hypothermy.

CONCLUSION

Follicular fluid responds endothermically to aqueous dilution and may contribute to follicular cooling during growth.

In vitro follicle growth: achievements in mammalian species

The exact mechanisms regulating in vivo folliculogenesis in mammalians have only been partly unravelled. Some processes, such as the initiation of growth of primordial follicles are still poorly understood. This increases the difficulty to culture follicles in vitro as the primordial follicles will be the ultimate starting material for culture. There are important species differences in regulation and timing of maturation, which makes it difficult to transpose techniques. Only in the mouse model, live pups were born when primordial or early preantral follicles were cultured entirely in vitro. Although no systems are as yet permitting complete in vitro culture of early follicle stages in large animals or humans, parts of folliculogenesis have been successfully reproduced in vitro. This review summarizes achievements of the last years in follicle culturing starting off at several stages of development. Future applications of in vitro follicle culture include fertility preservation for humans, preservation of rare animal species and creation of oocyte banks for research.

Amounts of selected coagulation factors in pre- and post-mortem follicular fluid are similar and do not correlate with molecular mass

This study was designed to evaluate the amounts of coagulation factors and to determine whether the protein profile in pre-ovulatory ovarian follicular fluid aspirated from ovaries collected from mares at slaughter are representative of that in follicular fluid collected from live animals. The proteins evaluated included, (i) albumin, ceruloplasmin and fibronectin, (ii) the procoagulant plasma proteins, Factor V (FV), Factor VII (FVII), Factor X (FX) and prothrombin, and (iii) the anticoagulant plasma proteins, antithrombin and alpha2-macroglobulin. The amounts of the individual proteins were similar in both types of follicular fluid. There was no correlation between the activity of FV, FVII, FX or prothrombin in follicular fluid and their molecular size although a correlation was found for the other proteins. These results suggest that the procoagulant proteins in follicular fluid are not likely derived from plasma. The total protein content of follicular fluid samples collected from both sources was similar and the results determined with the Biuret, Lowry and Biorad methods were also not significantly different (P>0.05).

Growth and antrum formation of bovine preantral follicles in long-term culture in vitro

Culture of preantral follicles has important biotechnological implications through its potential to produce large quantities of oocytes for embryo production and transfer. A long-term culture system for bovine preantral follicles is described. Bovine preantral follicles (166 +/- 2.15 micrometer), surrounded by theca cells, were isolated from ovarian cortical slices. Follicles were cultured under conditions known to maintain granulosa cell viability in vitro. The effects of epidermal growth factor (EGF), insulin-like growth factor (IGF)-I, FSH, and coculture with bovine granulosa cells on preantral follicle growth were analyzed. Follicle and oocyte diameter increased significantly (P < 0.05) with time in culture. FSH, IGF-I, and EGF stimulated (P < 0.05) follicle growth rate but had no effect on oocyte growth. Coculture with granulosa cells inhibited FSH/IGF-I-stimulated growth. Most follicles maintained their morphology throughout culture, with the presence of a thecal layer and basement membrane surrounding the granulosa cells. Antrum formation, confirmed by confocal microscopy, occurred between Days 10 and 28 of culture. The probability of follicles reaching antrum development was 0.19 for control follicles. The addition of growth factors or FSH increased (P < 0.05) the probability of antrum development to 0.55. Follicular growth appeared to be halted by slower growth of the basement membrane, as growing follicles occasionally burst the basement membrane, extruding their granulosa cells. In conclusion, a preantral follicle culture system in which follicle morphology can be maintained for up to 28 days has been developed. In this system, FSH, EGF, and IGF-I stimulated follicle growth and enhanced antrum formation. This culture system may provide a valuable approach for studying the regulation of early follicular development and for production of oocytes for nuclear/embryo transfer, but further work is required.

Ammonia concentration in bovine follicular fluid and its effect during in vitro maturation on subsequent embryo development

10 mm) to determine ammonia concentration. Ammonia concentration was greater (P<0.001) in the bFF from smaller follicles compared with bFF from larger follicles, and ammonia concentration decreased (P10 mm follicles, respectively. In Experiment 2, abattoir oocytes (n=2885) were matured in vitro in media containing ammonia at the concentrations of 0 microM (Control), 29 microM (A1), 88 microM (A2), 132 microM (A3), 176 microM (A4) and 356 microM (A5), followed by in vitro fertilization and culture. There was no difference (P0.05) in cleavage rates and morula or blastocyst development between treatments, indicating that in vitro exposure of bovine oocytes to ammonia does not adversely influence subsequent embryonic development.

Superoxide dismutase activity in human follicular fluid after controlled ovarian hyperstimulation in women undergoing in vitro fertilization

OBJECTIVE

To determine the activity of superoxide dismutase (SOD) and the total protein concentration in human preovulatory ovarian follicular fluid (FF) in relation to corresponding serum levels and the fertilization capacity of oocytes.

DESIGN

Prospective, observational study.

SETTING

Academic-based center for reproductive medicine.

PATIENT(S)

Twenty-eight female partners of infertile couples, 13 of whom were smokers, undergoing controlled ovarian hyperstimulation for IVF.

INTERVENTION(S)

Blood and follicular fluid samples were collected 34-36 hours after hCG administration.

MAIN OUTCOME MEASURE(S)

Levels of SOD activity and total protein concentrations.

RESULT(S)

Superoxide dismutase activity was present in all the FF studied and mean levels were statistically significantly higher than in serum. Total protein concentrations in serum were statistically significantly correlated with corresponding concentrations in FF. There was no difference in SOD activity between smokers and nonsmokers. Total protein concentrations in FF were marginally and statistically significantly lower in nonsmokers. Follicular fluid from patients whose oocytes did not become fertilized had a statistically significantly higher level of SOD activity than that from patients whose oocytes did become fertilized.

CONCLUSION(S)

Superoxide dismutase activity is present in FF and is higher than in serum. The degree of SOD activity is variable and seems to be inversely related to the fertilization of oocytes.

Messenger RNA expression and protein localization of growth hormone in bovine ovarian tissue and in cumulus oocyte complexes (COCs) during in vitro maturation

The aim of this study was to investigate whether bovine cumulus oocyte complexes (COCs) obtained from 2 to 8 mm follicles synthesize growth hormone (GH) during in vitro maturation. In addition the expression of growth hormone releasing hormone receptor (GHRH-r) in the COCs before and after in vitro maturation was investigated. Therefore, COCs obtained from small and medium sized follicles were cultured in M199 supplemented with 10% FCS and gonadotropins for 24 hr. At 0, 6, 12, and 24 hr after the onset of culture, COCs were removed and were prepared for immunohistochemical staining to detect the presence of GH. In addition, sections of ovary were stained to study the differential localization of GH in the ovary. At 0 and 24 hr COCs were removed and together with samples from granulosa cells and theca cells were prepared for reverse transcriptase polymerase chain reaction (RT-PCR) to assess the expression of mRNA of GH and GHRH-r. Within COCs, cumulus cells and oocytes showed GH immunoreactivity, while expression of GH mRNA was only found in the oocyte. At the onset of culture, oocytes and cumulus cells in the majority of COCs generally showed moderate and strong staining intensity for GH, respectively. While GH staining in the cumulus cells did hardly change during 24 hr of culture, GH staining in the oocyte was absent after 24 hr of culture in 70% of COCs. Within the ovary, GH was localized in antral follicles larger than 2 mm and no staining was found in primordial, primary and secondary follicles or in the stroma. The intensity of the staining increased with the size of the follicles. Within the follicular wall the GH was persistently observed in granulosa cells, while theca cells were occasionally negative. GH mRNA in follicular compartments was only found in the oocyte and mural granulosa cells. No GHRH-r mRNA was found in the COCs nor in the granulosa or the stroma. In conclusion, the gradual increase of GH staining during follicular development and the consistent synthesis of GH in oocytes and granulosa cells, suggest a paracrine and/or autocrine action for GH in bovine follicular growth and oocyte maturation. The absence of mRNA for GHRH receptor in the COCs indicates that ovarian production of GH is not regulated by GHRH.

Distribution of the alpha1 to alpha6 chains of type IV collagen in bovine follicles

During follicular development the proliferative and differentiated state of the epithelioid granulosa cells changes, and the movement of fluid across the follicular basal lamina enables the formation of an antrum. Type IV collagen is an important component of many basal laminae. Each molecule is composed of three alpha chains; however, six different type IV collagen chains have been identified. It is not known which of these chains are present in the follicular basal lamina and whether the type IV collagen composition of the basal lamina changes during follicular development. Therefore, we immunolocalized each of the six chains in bovine ovaries using antibodies directed to the nonconserved non-collagenous (NC) domains. Additionally, dissected follicles were digested with collagenase to release the NC domains, and the NC1 domains were then detected by standard Western immunoblot methods. The follicular basal lamina of almost all primordial and preantral follicles was positive for all type IV collagen alpha chains. Colocalization of type IV collagen and factor VIII-related antigen allowed for discrimination between the follicular and endothelial basal laminae. Type IV collagen alpha1, alpha2, alpha3, alpha4, and alpha5 chains were present within the follicular basal lamina of only a proportion of antral follicles (17 of 22, 20 of 21, 15 of 18, 14 of 28, and 12 of 23, respectively), and staining was less intense than in the preantral follicles. Staining for the alpha1 and alpha2 chains was diffusely distributed throughout the theca in regions not associated with recognized basal laminae. The specificity of this immunostaining for alpha1 and alpha2 chains of type IV collagen was confirmed by Western immunoblots. As well as being detected in the basal lamina of approximately half of the antral follicles examined, type IV collagen alpha4 also colocalized with 3beta-hydroxysteroid dehydrogenase-immunopositive cells in the theca interna. Type IV collagen alpha6 was detected in the basal lamina of only one of the 16 antral follicles examined. Thus, the follicular basal lamina changes in composition during follicular development, with immunostaining levels being reduced for all type IV collagen chains and immunoreactivity for type IV collagen alpha6 being lost as follicle size increases. Additionally, immunoreactivity for alpha1 and alpha2 appears in the extracellular matrix of the theca as it develops.

Magnesium as a regulator of thrombin formation in bovine ovarian follicular fluid

In the ovarian follicular fluid (FF) of Holstein cows, calcium (Ca) and magnesium (Mg) levels and their roles on thrombin generation were examined and compared with the blood samples. Total Ca levels in FF increased while the total Mg levels decreased with follicular development from preantral to preovulatory stage of follicles. These changes resulted in Ca values being significantly (p < 0.05) higher in FF from the most developed follicles and the Mg values being significantly higher (p < 0.05) in the least developed follicles. To determine whether the high level of Mg might function to regulate thrombin generation in FF as occurs in plasma, the influence of Mg supplementation of FF from various types of follicles was examined. In FF from small size follicles, Mg accelerated the prothrombin time, an estimation of the overall rate of thrombin production, although a similar effects was not observed in FF from medium and large size follicles. The addition of Mg to FF from all sizes of follicles resulted an inhibition in factor X activation. Since activation of factor X is a precursor step for thrombin formation it is concluded that Mg can function as a slow accelerator of thrombin generation in FF from follicles at the antral stage of development. It is likely to have a more important role in regulating the rate of thrombin generation as the follicle develops.

In vitro models for oocyte development

The mammalian ovary has a large store of primordial follicles, which are a potential source of oocytes for in vitro production of embryos. Several culture systems have been developed to support the growth and development of oocytes from rodent primordial and preantral follicles and progress is slowly being made in modifying these techniques to support the in vitro growth of porcine and bovine follicles. Oocytes from porcine preantral follicles can acquire competence to resume meiosis and proceed to Metaphase II after in vitro growth (IVG) but fertilisation has yet to be demonstrated. This paper presents the current status of technology for the in vitro growth and development of immature mammalian oocytes. Culture systems used successfully to grow immature rodent oocytes are compared and adaptations of these methods to support porcine and bovine oocyte growth discussed.

A comparison of the biochemical composition of equine follicular fluid and serum at four different stages of the follicular cycle

Samples of blood and follicular fluid were recovered from 27 Welsh Pony mares at 4 distinct stages of follicular development. Eighteen biochemical parameters were measured in each sample, including sodium, potassium, chloride, glucose, urea, creatinine, calcium, inorganic phosphate, total bilirubin, total protein, albumin, magnesium, triglyceride, total cholesterol, nonesterified fatty acids, alkaline phosphatase, gamma-glutamyltransferase and aspartate aminotransferase. The concentrations of progesterone, 17beta oestradiol and testosterone, pH and osmolarity, were also measured in all the follicular fluid samples. The concentrations of all proteins measured were lower in follicular fluid than serum whereas the reverse was true in the case of the lipids. Analysis of variance indicated that serum and follicular fluid concentrations of most of the parameters measured varied in parallel.

Fibronectin concentrations correlate with ovarian follicular size and estradiol values in equine follicular fluid

The amounts of total protein, albumin, fibronectin, alpha 2-macroglobulin (alpha 2-M), immunoglobulin G, ceruloplasmin and antithrombin were determined in fluids collected from 53 preovulatory equine follicles and compared with the contents of estradiol-17 beta, progesterone and androstenedione, with follicle size and the amounts of the equivalent proteins in normal equine plasma. The concentration of fibronectin and the fibronectin/albumin ratios increased significantly with follicle size and with follicular estradiol levels. The alpha 2-M levels and alpha 2-M/albumin ratios correlated with follicle size but not with hormone content. Both fibronectin and alpha 2-M were present in lower amounts in follicular fluid compared with plasma while the other proteins were present in similar amounts. Among the proteins evaluated, there was a positive correlation between the amount of the protein in the follicular fluid and the molecular weight of the protein.

Normal oxygen atmosphere is essential for the solitary long-term culture of early preantral mouse follicles

This study compares the effects of reduced (5%) or normal (5% CO2 in air; 20% O2) oxygen tension on the in vitro maturation of early preantral ovarian follicles isolated from 14-day-old (C57BI/6J x CBAca) F1 mice. Intact follicles (100-130 microns) are singly cultured in 20 microliters droplets alpha-MEM enriched with FCS and rFSH under mineral oil at 37 degrees C and 100% humidity. In this culture system the follicles are allowed to attach to the bottom of the petri dishes. Follicle in vitro growth, hormone secretory capacity, and in vitro ovulation were studied under the two oxygen tensions. Spontaneous oocyte release from the follicle during a 16-day culture period was observed significantly more under 5% oxygen. Antral-like cavity formation was not observed under 5% O2. The follicles in the 5% O2 cultures reaching day 16 were stripped of their granulosa cell layers, and 83% of the retrieved oocytes had already undergone spontaneous germinal-vesicle breakdown (GVBD). Under 20% O2, the GV stage was maintained until day 16 in 77% of the oocytes. Under 5% O2, intact follicle survival up to day 12 was significantly reduced as compared to the 5% CO2 in air conditioning. The hCG stimulus on day 12 induced mucification in a significantly larger proportion of follicles cultured under 20% O2 (79% vs. 47%). Germinal-vesicle breakdown (20% O2:95, 5%, O2:42%) and first polar body extrusion (20% O2:40%, 5% O2:15%) were significantly more prevalent under normal oxygen tension. A reduced secretory capacity of E2 and inhibin was demonstrated for follicles cultured under 5% O2. The histological study of serially sectioned follicles showed increased areas of centrally located granulosa cell necrosis and pyknosis in the cumulus cells. Gassing follicle cultures using 5% CO2 in air provided appropriate conditions for normal growth, enhanced whole-follicle survival, differentiation, and hormone production, and improved the yield of meiotic competent oocytes.

The hemostatic profile of equine ovarian follicular fluid

The coagulation factors VII and X and fibrinogen were detected in equine ovarian follicular fluid. The amounts of fibrinogen and factor X were approximately 40 percent of that found in normal equine plasma while the level of factor VII was lower, at approximately 14 percent. The addition of human recombinant tissue factor caused fibrin formation in the follicular fluid. The thrombin generating activity appears to be confined to the tissue factor pathway since no activity associated with factors VIII:C, IX or IX was detected. Fibrinolytic activity, at higher levels than that found in plasma, was detected in all follicular fluid samples. It is proposed that the hemostatic mechanism may be modulated in follicular fluid in a manner analogous to that in plasma since inhibitory proteins including AT-III and antiplasmin were present in the follicular fluid samples at relatively constant levels that approached those found in normal equine plasma.

Spectrophotometric absorbance of follicular fluid: a selection criterion

PURPOSE

The aim of this study was to ascertain the absorbance profiles of uncontaminated follicular fluids (FF) vs blood and medium contaminated FF, and to test the hypothesis that blood contamination alters the biochemical status of FF.

METHODS

FF (n = 655) from 230 patients were scanned spectrophotometrically during an ongoing in vitro fertilization (IVF) program. Based on spectrophotometric evaluation, blood contaminated and uncontaminated FF (n = 39 patients/FF) were analyzed for electrolyte content, inorganic phosphate, glucose, creatine, urate, total protein, albumin, bilirubin, cholesterol, alkaline phosphatase, gamma-glutamyltransferase, alanine aminotransferase, aspartate transaminase, and lactate dehydrogenase by means of a SMAC analyzer.

RESULTS

Laparoscopic aspiration resulted in the collection of significantly more clear FF compared to the transvaginal procedure (P = 0.001). Uncontaminated fluid depicted a single mean absorbance at 458.0 nm. Blood contaminated FF could be identified by spectrophotometry and revealed three peaks at 418.12, 540.13, and 575.32 nm, respectively, according to the degree of blood contamination. Follicular fluid diluted with Earles Balanced Salt Solution (EBSS) displayed an additional mean peak at 561.4 nm. Potassium, glucose, and all of the above mentioned enzymes revealed significantly higher levels in blood contaminated FF (P < 0.05).

CONCLUSIONS

From this study, it is concluded that blood contamination and dilution with culture medium influence the biochemical composition as well as the absorbance spectrum of follicular fluids. This procedure is advocated as a prerequisite before quantifying FF content.

Protein composition of follicular fluid and oocyte cleavage occurrence in in vitro fertilization (IVF)

The present study was carried out from in vitro fertilization (IVF) attempts to analyze further the total and specific protein contents of 47 follicular fluids yielding one oocyte. The aim was to find correlations between the follicular concentrations of such proteins and the occurrence of coupled oocyte cleavage. These findings would be used as markers of IVF outcome. Two groups of follicular samples were distinguished: one group with cleavage occurrence (25 cases) and another group without cleavage or even fertilization (22 cases). In the group with cleavage a significantly higher level was observed for six proteins: C3 complement fraction and ceruleoplasmin (P less than 0.02), alpha-antitrypsin and transferrin (P less than 0.01), and alpha 2-macroglobulin and beta 2-microglobulin (P less than 0.001). The data are discussed with respect to changes in follicle permeability with advancing maturity.