Relationship of human oocyte maturity, fertilization, and cleavage to follicular fluid prolactin and steroids

Prolactin Relationship with Fertility and In Vitro Fertilization Outcomes-A Review of the Literature

Hyperprolactinemia is a known cause of amenorrhea and infertility. However, there is an increasing body of evidence suggesting that prolactin is involved in multiple physiological aspects of normal reproduction. Thus, the present paper aims to review the current literature regarding the relationship between serum prolactin level and in vitro fertilization (IVF)/intracytoplasmic sperm injection outcome and the role of dopamine agonists treatment in IVF success. Moreover, the mechanisms by which prolactin may exert its role in fertility and infertility were summarized. Although not all studies agree, the available evidence suggests that higher prolactin levels in follicular fluid are associated with increased oocytes competence, but also with positive effects on corpus luteum formation and survival, endometrial receptivity, blastocyst implantation potential and survival of low-motile sperm. Transient hyperprolactinemia found in IVF cycles was reported in most of the studies not to be related to IVF outcome, although a few reports suggested that it may be associated with higher implantation and pregnancy rates, and better-cumulated pregnancy outcomes. Administration of dopamine agonists for hyperprolactinemia preceding IVF treatment does not seem to negatively impact the IVF results, while treatment of transient hyperprolactinemia during IVF might be beneficial in terms of fertilization rates and conception rates. Due to limited available evidence, future studies are necessary to clarify the optimal level of circulating prolactin in patients performing IVF and the role of dopamine agonist treatment.

Non-invasive oocyte quality assessment

Oocyte quality is perhaps the most important limiting factor in female fertility; however, the current methods of determining oocyte competence are only marginally capable of predicting a successful pregnancy. We aim to review the predictive value of non-invasive techniques for the assessment of human oocytes and their related cells and biofluids that pertain to their developmental competence. Investigation of the proteome, transcriptome, and hormonal makeup of follicular fluid, as well as cumulus-oocyte complexes are currently underway; however, prospective randomized non-selection-controlled trials of the future are needed before determining their prognostic value. The biological significance of polar body morphology and genetics are still unknown and the subject of debate. The predictive utility of zygotic viscoelasticity for embryo development has been demonstrated, but similar studies performed on oocytes have yet to be conducted. Metabolic profiling of culture media using human oocytes are also limited and may require integration of automated, high-throughput targeted metabolomic assessments in real time with microfluidic platforms. Light exposure to oocytes can be detrimental to subsequent development and utilization of time-lapse imaging and morphometrics of oocytes is wanting. Polarized light, Raman microspectroscopy, and coherent anti-Stokes Raman scattering are a few novel imaging tools that may play a more important role in future oocyte assessment. Ultimately, the integration of chemistry, genomics, microfluidics, microscopy, physics, and other biomedical engineering technologies into the basic studies of oocyte biology, and in testing and perfecting practical solutions of oocyte evaluation, are the future for non-invasive assessment of oocytes.

Prolactin from Pluripotency to Central Nervous System Development

Prolactin (PRL) is a versatile hormone that exerts more than 300 functions in vertebrates, mainly associated with physiological effects in adult animals. Although the process that regulates early development is poorly understood, evidence suggests a role of PRL in the early embryonic development regarding pluripotency and nervous system development. Thus, PRL could be a crucial regulator in oocyte preimplantation and maturation as well as during diapause, a reversible state of blastocyst development arrest that shares metabolic, transcriptomic, and proteomic similarities with pluripotent stem cells in the naïve state. Thus, we analyzed the role of the hormone during those processes, which involve the regulation of its receptor and several signaling cascades (Jak/Mapk, Jak/Stat, and PI3k/Akt), resulting in either a plethora of physiological actions or their dysregulation, a factor in developmental disorders. Finally, we propose models to improve the knowledge on PRL function during early development.

An increase of phosphatidylcholines in follicular fluid implies attenuation of embryo quality on day 3 post-fertilization

Background

Although oocyte quality is the dominant factor determining embryo quality, few studies have been conducted to evaluate embryo quality based on the metabolites related to the oocyte. With quantification of the follicular fluid (FF) metabolites, in assisted reproductive technology (ART), this study sought to evaluate the embryo or oocyte quality through an informative approach.

Results

An evaluation model consisting of 17 features was generated to distinguish the embryo quality on day 3 post-fertilization, and phosphatidylcholines (PCs) were the key contributors to the evaluation. The model was extended to the patients under different ages and hyperstimulations, and the features were further enriched to facilitate the evaluation of the embryo quality. The metabolites were clustered through pathway analysis, leading to a hypothesis that accumulation of arachidonic acid induced by PCs might weaken embryo quality on day 3 post-fertilization.

Conclusions

A discriminating model with metabolic features elicited from follicular fluid was established, which enabled the evaluation of the embryo or oocyte quality even under certain clinical conditions, and the increase of PCs in follicular fluid implies the attenuation of embryo quality on day 3 post-fertilization.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-021-01118-w.

The follicular fluid adipocytokine milieu could serve as a prediction tool for fertility treatment outcomes

RESEARCH QUESTION

Can the adipocytokine milieu of the follicular niche improve the ability to predict treatment outcomes in infertile patients?

DESIGN

Follicular fluid samples from overweight patients were analysed and compared with samples from matched normal-weight patients. Concentrations of adiponectin, chemerin, C-reactive protein, interleukin-6 (IL-6), IL-10, IL-18, insulin, leptin, prolactin, resistin, tumour necrosis factor alpha (TNF-α) and bone morphogenetic protein-15 (BMP-15) were assessed by multiple magnetic bead immunoassay (MMBI) and enzyme-linked immunosorbent assay and correlated with fertility treatment outcomes.

RESULTS

Analysis of samples from 22 overweight and 22 normal-weight patients demonstrated that TNF-α can predict oocyte maturation rate. When stratified by body mass index (BMI), IL-10 emerges as a better predictor of oocyte maturation in normal-weight patients. Prolactin was a negative predictor for fertilization rate in the full cohort, and this prediction power was lost upon stratification. No adipocytokines were predictive of blastulation rate, and only age remained predictive. BMP-15 was a strong predictor of high-quality blastulation in the full cohort, more so in the normal-weight population.

CONCLUSIONS

The adipocytokine milieu of the follicular fluid provides a snapshot of the growing oocyte's environment and can help predict fertility treatment outcomes, fine-tuning understanding of the dysregulation caused by increasing BMI. Inflammatory cytokines can predict oocyte maturation; prolactin, oocyte competence; and BMP-15, high-quality blastulation. Further analysis of these findings with a larger sample size and assessing individual oocytes will help shed more light on the clinical significance of these findings.

LH supplementation of ovarian stimulation protocols influences follicular fluid steroid composition contributing to the improvement of ovarian response in poor responder women

In this prospective study, we evaluated the steroid levels in 111 follicular fluids (FF) collected from 13 women stimulated with FSH monotherapy and 205 FF collected from 28 women stimulated with FSH + LH because of a previous history of hypo-responsiveness to FSH. Steroid levels were measured by HPLC/MS–MS and related to ovarian stimulation protocol, oocyte maturity, fertilization and quality of blastocysts, after individually tracking the fate of all retrieved oocytes. 17-Hydroxy-Progesterone, Androstenedione, Estradiol and Estrone were significantly higher in the FSH + LH protocol. Progesterone, 17-Hydroxy-Progesterone and Estradiol were more expressed in FF yielding a mature oocyte (p < 0.01) in the FSH + LH protocol. FF Progesterone concentration was correlated with the rate of normal fertilization in the FSH protocol. None of the FF steroids measured were associated with blastocyst quality and achievement of pregnancy. Our results indicate that LH supplementation in hypo-responsive women modifies ovarian steroid production, mimicking physiological production better and likely contributing to an improved ovarian response. Employing a correct methodological procedure to evaluate the relationship between FF steroid hormones and assisted reproduction outcomes, our study reveals that some steroids in single follicles may be helpful in predicting oocyte maturity and fertilization.

Serum substance P concentrations to predict oocyte maturation index and clinical pregnancy

AIM

The aim of this study was to assess the predictive value of serum substance P (SP) concentrations on oocyte maturation and clinical pregnancy.

METHODS

Ninety-three women with unexplained infertility underwent intracytoplasmic sperm injection (ICSI) cycles. Antagonist protocol was started for each participant and at the day of oocyte pick up, serum samples were obtained from each participant to assess SP concentrations, and these concentrations were utilized to predict mature/total oocyte ratio and clinical pregnancy.

RESULTS

SP concentration was a significant predictor for mature/total oocyte ratio > 0.75 and clinical pregnancy. In correlation analyses, maturation index was significantly correlated with FSH (r= -0.226, p = 0.03), estradiol (r = 0.239, p = 0.021), peak estradiol (r = 0.414, p < 0.001), and substance P (r = 0.796, p < 0.001). In multivariate analyses, number of immature (beta coefficient = -0.379, p < 0.001), mature oocyte (beta coefficient = 0.473, p < 0.001), SP concentration (beta coefficient = 0.723, p < 0.001) and maturation index (beta coefficient = -0.387, p = 0.003) were significantly associated with clinical pregnancy.

CONCLUSION

SP concentrations at the day of oocyte pick up may be used to predict clinical pregnancy and may be an indirect indicator for cycle outcome in assisted reproductive technology (ART).

Follicular-fluid anti-Mullerian hormone (FF AMH) is a plausible biochemical indicator of functional viability of oocyte in conventional in vitro fertilization (IVF) cycles

CONTEXT

Oocyte quality may be a governing factor in influencing in vitro fertilization (IVF) outcomes. However, morphological evaluation of oocyte quality is difficult in conventional IVF cycles. Follicular-fluid (FF), the site for oocyte growth and development, has not yet been sufficiently explored to obtain a marker indicative of oocyte quality. Anti-Mullerian hormone (AMH) is produced by granulosa cells of preantral and early-antral follicles and is released in FF.

AIM

To investigate AMH as a biochemical indicator of functional viability/quality of oocyte produced in the FF micro-environmental milieu.

SETTINGS AND DESIGN

Prospective study involving 132 cycles of conventional IVF-embryo transfer (ET) in infertile women.

SUBJECTS AND METHODS

AMH concentration was estimated in pooled FF on day of oocyte pickup. Cycles were sorted into low and high groups according to median (50 (th) centile) values of measurement. Main outcome measure was oocyte viability, which included morphological assessment of oocyte quality, fertilization rate, clinical pregnancy, and implantation rates.

STATISTICAL ANALYSIS

Graph-pad Prism 5 statistical package.

RESULTS

Low FF AMH group shows significantly higher percentage of top-quality oocytes (65.08 ± 24.88 vs. 50.18 ± 25.01%, P =0.0126), fertilization (83.65 ± 18.38 vs. 75.78 ± 21.02%, P =0.0171), clinical pregnancy (57.57 vs. 16.67%, P >0.0001), and embryo implantation rates (29.79 vs. 7.69%, P >0.0001) compared to high FF AMH group. FF AMH shares an inverse correlation with FF E2 (Pearson r = -0.43, r(2) = 0.18) and clinical pregnancy (Pearson r = -0.46, r(2) = 0.21). Threshold value of FF AMH for pregnancy is >1.750 ng/mg protein.

CONCLUSION

FF AMH is a plausible biochemical indicator of functional viability of oocyte in conventional IVF cycles.

Serum human chorionic gonadotropin levels on the day before oocyte retrieval do not correlate with oocyte maturity

OBJECTIVE

To evaluate the correlation of preretrieval quantitative serum hCG level with oocyte maturity.

DESIGN

Retrospective cohort study.

SETTING

Military assisted reproductive technology (ART) program.

PATIENT(S)

Fresh autologous ART cycles.

INTERVENTION(S)

Serum hCG level the day before oocyte retrieval.

MAIN OUTCOME MEASURE(S)

Linear regression was used to correlate serum hCG levels and oocyte maturity rates. Normal oocyte maturity was defined as ≥75% and the Wilcoxon rank sum test was used to compare serum hCG levels in patients with normal and low oocyte maturity. Threshold analysis was performed to determine hCG levels that could predict oocyte maturity.

RESULT(S)

A total of 468 ART cycles were analyzed. Serum hCG level was not correlated with hCG dose; however, it was negatively correlated with body mass index (BMI). Serum hCG levels did not differ between patients with oocyte maturity of <75% and ≥75%. Serum hCG levels did not correlate with oocyte maturity rates. Receiver operator characteristic and less than efficiency curves failed to demonstrate thresholds at which hCG could predict oocyte maturity.

CONCLUSION(S)

Serum hCG levels were not correlated with oocyte maturity. Although a positive hCG was reassuring that mature oocytes would be retrieved for most patients, the specific value was not helpful.

Metabolite Profiling in the Pursuit of Biomarkers for IVF Outcome: The Case for Metabolomics Studies

Background. This paper presents the literature on biomarkers of in vitro fertilisation (IVF) outcome, demonstrating the progression of these studies towards metabolite profiling, specifically metabolomics. The need for more, and improved, metabolomics studies in the field of assisted conception is discussed. Methods. Searches were performed on ISI Web of Knowledge SM for literature associated with biomarkers of oocyte and embryo quality, and biomarkers of IVF outcome in embryo culture medium, follicular fluid (FF), and blood plasma in female mammals. Results. Metabolomics in the field of female reproduction is still in its infancy. Metabolomics investigations of embryo culture medium for embryo selection have been the most common, but only within the last five years. Only in 2012 has the first metabolomics investigation of FF for biomarkers of oocyte quality been reported. The only metabolomics studies of human blood plasma in this context have been aimed at identifying women with polycystic ovary syndrome (PCOS). Conclusions. Metabolomics is becoming more established in the field of assisted conception, but the studies performed so far have been preliminary and not all potential applications have yet been explored. With further improved metabolomics studies, the possibility of identifying a method for predicting IVF outcome may become a reality.

The effects of GnRH analogs on serum and follicular fluid leptin levels and pregnancy outcomes in short protocols of assisted reproductive technology

OBJECTIVE

To determine serum and follicular leptin levels in patients using gonadotropin releasing hormone agonist and antagonist in Assisted Reproductive Technology short protocol cycles and to evaluate pregnancy outcomes.

MATERIAL AND METHODS

Patients randomly selected to join assisted reproductive technology cycles during February 2004-July 2004 were enrolled in this study. Group 1 consisted of 21 patients receiving r FSH+ GnRH agonists, whereas Group 2 consisted of 34 patients who received r FSH +GnRH antagonists. During the ovulation induction period 5 serum samples were collected (induction day 1, day 3 or antagonist starting day, human chorionic hormone day, oocyte pickup day, and twelfth day of embryo transfer). Follicular fluid samples were collected to be evaluated for leptin, estradiol, prolactin and luteinizing hormone.

RESULTS

There was no difference in age, basal FSH, basal LH, and basal E2 between groups. Serum leptin levels were similar in both groups. Also, when each group's serum leptin levels were evaluated according to the presence of pregnancy, there was no significant difference in both groups. When follicle leptin levels were evaluated according to the existence of pregnancy, in both groups the follicle leptin levels were lower in pregnant participants but this difference was not statistically significant. When obesity is defined as body mass index over 26.5, there is a correlation between obesity and leptin levels in Group 2.

CONCLUSION

Our results have shown that both agonists and antagonists have similar efficacy and effect in poor responder women. Leptin levels in either groups, whether pregnant or non-pregnant were not statistically different. This result shows the need for more studies on leptin in infertility.

Follicular fluid content and oocyte quality: from single biochemical markers to metabolomics

The assessment of oocyte quality in human in vitro fertilization (IVF) is getting increasing attention from embryologists. Oocyte selection and the identification of the best oocytes, in fact, would help to limit embryo overproduction and to improve the results of oocyte cryostorage programs. Follicular fluid (FF) is easily available during oocyte pick-up and theorically represents an optimal source on non-invasive biochemical predictors of oocyte quality. Unfortunately, however, the studies aiming to find a good molecular predictor of oocyte quality in FF were not able to identify substances that could be used as reliable markers of oocyte competence to fertilization, embryo development and pregnancy. In the last years, a well definite trend toward passing from the research of single molecular markers to more complex techniques that study all metabolites of FF has been observed. The metabolomic approach is a powerful tool to study biochemical predictors of oocyte quality in FF, but its application in this area is still at the beginning. This review provides an overview of the current knowledge about the biochemical predictors of oocyte quality in FF, describing both the results coming from studies on single biochemical markers and those deriving from the most recent studies of metabolomics.

Efficacy of low-dose human chorionic gonadotropin alone to complete controlled ovarian stimulation

OBJECTIVE

To prove that low-dose hCG alone can be clinically used to replace FSH-containing gonadotropins to complete controlled ovarian hyperstimulation (COH).

DESIGN

Controlled, prospective, randomized study.

SETTING

Academic center.

PATIENT(S)

Infertile patients who are candidates for assisted reproduction.

INTERVENTION(S)

Patients received [1] recombinant FSH or hMG throughout COH (group A); [2] ovarian priming with recombinant FSH/hMG followed by low-dose hCG (200 IU/day) alone (group B).

MAIN OUTCOME MEASURE(S)

Medication consumption; daily serum and follicular fluid (FF) measurements of LH, FSH, hCG, E2, P, T, and androstenedione (A); number and size of follicles; intracytoplasmic sperm injection (ICSI) outcome.

RESULT(S)

In group B: [1] duration and dose of recombinant FSH/hMG administration were reduced; [2] preovulatory serum hCG, E2, and T were higher, whereas FSH was lower; [3] FF hCG, E2, T levels, and E2/T, E2/A, and E2/P ratios were higher, whereas A was lower; [4] small but not large preovulatory follicles were reduced; [5] fertilization rates were higher; and [6] serum and FF P levels, and ICSI outcome did not differ.

CONCLUSION(S)

Low-dose hCG alone in the late COH stages: [1] reduced recombinant FSH/hMG consumption whereas ICSI outcome was comparable to traditional COH regimens; [2] stimulated follicle growth and maturation independent of FSH administration; [3] was associated with a reduced number of small preovulatory follicles; [4] did not cause premature luteinization; [5] resulted in a more estrogenic intrafollicular environment.

Correlations between steroids concentration in follicular fluid, pronuclear morphology and embryo qualities in in vitro fertilization

Background:  Several parameters of early embryo development are known as predictors of implantation success. Recently, zygote or embryo morphological assessments are thought to be a major method of selection in embryo transfer. We expected that the concentrations of the steroids in follicular fluid (FF) were associated with oocyte maturation and embryo quality. In the present paper, we evaluated the relationship of several parameters. Methods:  We investigated 105 samples of FF from 22 subjects by in vitro fertilization (IVF). We evaluated the correlations between the FF concentrations of estradiol (E₂) and progesterone (P₄), the diameter of the ovarian follicles, fertilization, and zygote assessment based on pronuclear morphology and day 3 embryo qualities (i.e. number of blastomeres and fragmentation rate). Results:  There was a positive correlation between the E₂ concentrations in FF and serum (r = 0.273, P < 0.01), but there was no correlation between follicular diameter and the FF concentration of each steroid. The concentration of E₂ in FF containing fertilized oocytes was not significantly different from that in FF containing unfertilized oocytes. At the pronuclear stage, the concentration of either steroid in FF did not differ among the morphological groups. The concentration of P₄ in FF was significantly lower in the group in which pronuclei were detected at 20 h after insemination than in the group in which pronuclei were not detected. The concentration of E₂ in FF was significantly related to the number of blastomeres (r = 0.271, P < 0.05) and furthermore, was significantly higher in FF from which morphologically good embryos were obtained at day 3 (P < 0.05). Conclusions:  The FF concentrations of the steroids did not affect the pronuclear pattern, but P₄ production may play a role in reducing the potential of the oocyte to develop pronuclei and the concentration of E₂ may predict the cleavage capability of the oocyte. (Reprod Med Biol 2003; 2: 171-176).

Follicle stimulating hormone effects on immature human oocytes: in vitro maturation and hormone production

PURPOSE

Our purpose was (1) to determine if in vitro maturation of unstimulated oocytes could be improved with the addition of urofollitropin; (2) to evaluate the output of estradiol, testosterone, progesterone, and androstenedione by the cultured oocyte-cumulus complex; and (3) to ascertain if steroid hormone production of the oocyte-cumulus complex correlates with final oocyte maturation stage.

METHODS

Fifty-eight immature oocytes were obtained from 11 regularly cycling women undergoing oophorectomy. The oocyte-cumulus complexes were randomly assigned to control medium (Ham's F-10 supplemented with 7.5% fetal bovine serum) or test medium (control medium supplemented with 75 mIU/ml of urofollitropin).

RESULTS

(1) The addition of urofollitropin to oocyte culture medium does not significantly increase the ability of the oocyte to achieve the metaphase II stage; (2) the addition of urofollitropin significantly increases the production of progesterone, testosterone, and androstenedione by the oocyte-cumulus complex; and (3) there is no difference in the production of estradiol, progesterone, testosterone, and androstenedione by the oocyte-cumulus complex at the germinal vesicle, metaphase I or metaphase II stage of oocyte maturation.

CONCLUSIONS

This information is of importance in the use of oophorectomy specimens for patients who must undergo an oophorectomy but desire to attempt pregnancy using their oocytes, in the use of oophorectomy specimens for donor oocytes, or for patients undergoing in vitro fertilization using immature oocyte collection.

The detection of blood contamination in human follicular fluid

PURPOSE

The aim of this study was to compare the reliability of the methods conventionally used to identify low levels of blood contamination in human follicular fluid (hFF) as applicable in the clinical environment.

METHODS

Follicular fluid (n = 339) and plasma samples (n = 20) were collected from patients (n = 138) attending the Centre for Fertility Studies, HF Verwoerd Hospital, University of Pretoria, South Africa. hFF blood contamination was assessed by means of (a) visual inspection, (b) hematocrit (Hct), (c) spectrophotometric analysis, (d) spectrophotometric hemoglobin kit, and (e) Combur-9-test urine sticks.

RESULTS

(1) Neither hematocrit nor spectrophotometry provided reliable detection at low levels of blood contamination. (2) Visual inspection presented with a better discriminatory ability than either Hct or spectrophotometry. (3) Combur-9-test sticks identified up to 50% of blood-contaminated fluids. (4) Spectrophotometrically determined hemoglobin levels presented with weak discriminatory abilities for detecting blood-contaminated fluids.

CONCLUSIONS

Visual inspection as performed in this study provides a fast and relatively reliable method for the determination of blood-contaminated hFFs. In a laboratory environment, however, it would be recommended that a combination of visual inspection, Hct, and spectrophotometric evaluation be employed for the selection of blood-free fluids.

Viscosity and refractive index of follicular fluid in relation to in vitro fertilization

PURPOSE

To set the standard values of follicular fluid viscosity and refractive index, and to investigate a possible relationship between these physiological parameters and the outcome of in vitro fertilization treatment.

DESIGN AND RESULTS

128 samples of follicular fluid were collected from 40 in vitro fertilization patients. Viscosity determinations (centipoise; mean +/- SD) for shear rates of 23, 46, 115, and 230 were 2.04 +/- 0.86, 1.84 +/- 0.49, 1.48 +/- 0.27, and 1.38 +/- 0.22, respectively. The average (+/- SD) refractive index was 1.030 +/- 0.002. There was no significant difference between the values of thawed frozen fluids and fresh samples of the same specimens. The data showed no correlation between follicular fluid viscosity or refractive index and the presence of oocytes, their maturation grade or their fertilizing capacity.

CONCLUSIONS

For the first time, values of the viscosity and refractive index of follicular fluid obtained during in vitro fertilization have been determined. However, these preliminary results did not reveal any relationship between the physiological parameters examined and the outcome of in vitro fertilization treatment.

Flow cytometric evaluation of leukocyte subpopulations in the follicular fluids of infertile patients

OBJECTIVES

To evaluate the leukocyte subpopulations present in follicular fluid (FF) of infertile patients undergoing IVF-ET for tubal factor, idiopathic infertility, and endometriosis.

PATIENTS

Sixty patients undergoing IVF-ET with a tubal factor diagnosis (n = 35), idiopathic infertility (n = 13), and endometriosis (n = 12) had their subpopulations of FF leukocytes analyzed by flow cytometry.

MAIN OUTCOME MEASURE

Nonblood-contaminated samples of FF were collected under sterile conditions and centrifuged. Cells were labeled with a panel of monoclonal antibodies: anti-CD3, -CD4, -CD8, -CD14, -CD20, -CD45, and -CD56, and analyzed by cytofluorometry.

RESULTS

Follicular fluid leukocytes from patients with idiopathic infertility had a significantly higher proportion of T lymphocytes than tubal factor and endometriosis patients. Endometriosis patients had significantly higher proportions of natural killer (NK) cells, B lymphocytes, and monocytes compared with groups of idiopathic infertility and tubal factor.

CONCLUSIONS

The differences observed in the leukocyte subpopulations from FF of patients with idiopathic infertility and endometriosis may affect folliculogenesis and oocyte maturation. Moreover, these modifications could be one of the factors altering their fertility.

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.

Epidermal growth factor in human follicular fluid stimulates mouse oocyte maturation in vitro

OBJECTIVE

To study the effect of human follicular fluid (FF) and the specific contribution of its epidermal growth factor (EGF) component on the in vitro maturation of cumulus-enclosed mouse oocytes.

DESIGN

A previously described mouse oocyte model system was used to study the effect of FF on oocyte maturation before and after extraction of EGF by immunoprecipitation. Follicular fluid specimens enclosing both mature and immature human oocytes were tested.

MAIN OUTCOME MEASURES

The endpoints assessed were the percentage of oocytes undergoing germinal vesicle breakdown (GVBD) and polar body one formation at different intervals over a 24-hour period and the final degree of cumulus expansion achieved.

RESULTS

A concentration-related stimulatory effect of mature FF was noted when compared with the spontaneous increase of GVBD and polar body one formation observed for the EGF-free control medium. Overall, the effect of immature FF was inhibitory. After extraction of EGF from FF by immunoprecipitation from both immature and mature FF, the rates of GVBD and polar body one formation were decreased in both groups. The addition of 5 ng/mL of EGF to the extracted groups reversed this effect on polar body one formation. Cumulus expansion was maximal for oocytes incubated with mature FF and minimal for those incubated with EGF-free media.

CONCLUSIONS

The positive effect of mature human FF on mouse oocyte maturation and cumulus expansion is to a large extent because of the presence of EGF.

Androstenedione and progesterone concentrations in preovulatory follicular fluid correlate with successful fertilization and cleavage of human oocytes in vitro

OBJECTIVE

To determine if androstenedione (A) and progesterone (P) concentrations in preovulatory follicular fluid (FF) correlate with successful fertilization and cleavage of human oocytes in vitro.

DESIGN

A retrospective randomized trial.

SETTING

Hospital department of obstetrics and gynecology.

PATIENTS

Fifty-five patients, ages 24 to 39 years, with normal menstrual cycles undergoing in vitro fertilization (IVF) for tubal infertility.

INTERVENTIONS

Multiple follicular development was induced with clomiphene citrate and human menopausal gonadotropin.

MAIN OUTCOME MEASURES

Relationships among FF steroid hormone, morphological maturity of oocyte-corona-cumulus complexes, and fertilization and cleavage of oocytes.

RESULTS

Follicles with mature oocyte-corona-cumulus complexes and unfertilized oocytes contained significantly greater amounts of A (P less than 0.05) than those with mature oocyte-corona-cumulus complexes and fertilized ova, indicating the occurrence of atretic changes. Follicles yielding successfully fertilized and cleaved ova had significantly greater amounts of P (P less than 0.05) and A (P less than 0.01) but similar levels of 17 beta-estradiol compared with follicles yielding fertilized ova that failed to cleave.

CONCLUSIONS

Follicles yielding oocytes that cleaved as a result of IVF have both a shift in steroidogenesis from estrogen to progestin accumulation and declining aromatase activity, thus reflecting progressive luteinization of the follicles.

Oocyte and follicular fluid characteristics in women with mild endometriosis

The follicular development, fertilization and cleavage rates and follicular fluid endocrinology were assessed in 20 women with mild endometriosis during a spontaneous menstrual cycle. Diagnostic laparoscopy was performed 32 h after the onset of the endogenous luteinizing hormone (LH) surge in the 20 women with laparoscopically confirmed mild endometriosis and in a control group of ten women with tubal infertility. There was no significant difference in oocyte maturity or fertilization and cleavage rates between the women with mild endometriosis and those in the control group. The endocrine milieu of the pre-ovulatory oocyte at the time of aspiration was similar in the two groups.

Correlations between follicular fluid steroid analysis and maturity and cytogenetic analysis of human oocytes that remained unfertilized after in vitro fertilization

OBJECTIVE

Is there any correlation between follicular fluid (FF) steroid levels and the occurrence of cytogenetic abnormalities in unfertilized human oocytes?

DESIGN

Cytogenetic analysis was carried out on 397 oocytes, and the steroid content of 104 corresponding FF was analyzed using high-pressure liquid chromatography. Ovarian stimulation was performed by clomiphene citrate and human menopausal gonadotropin (hMG) or by hMG combined with a gonadotropin-releasing hormone agonist (GnRH-a) pretreatment.

RESULTS

Oocyte maturity was correlated with an increasing FF progestin content and a significant decrease of androstenedione (A) levels. Chromosomal analysis revealed 84 of all oocytes to be abnormal (polyploid or aneuploid and/or prematurely condensed chromosomes present). In this group, A levels and A to estradiol ratios were significantly higher. Although progestin levels were higher in GnRH-a/hMG cycles, the incidence of oocyte normality was not different between the two stimulation schemes. More abnormal oocytes were found in patients with good sperm morphology.

CONCLUSIONS

Oocyte abnormality correlates with higher A levels in the corresponding FF. Oocyte fertilization is also determined by intrinsic oocytic factors other than maturity.

Follicular fluid steroid levels in relation to oocyte maturity and in vitro fertilization

Steroid levels in follicular fluid (FF) obtained from stimulated ovaries in patients undergoing in vitro fertilization (IVF) were measured by capillary gas chromatography. The correlation between these levels and the maturity of the oocyte, judged from the morphology of the oocyte corona cumulus complex (OCCC) and the fertilizability of the oocytes was analysed. Oocyte maturity was associated with higher FF levels of progesterone, 17-hydroxyprogesterone, 16 alpha-hydroxyprogesterone and 20 alpha-dihydroprogesterone. Follicular fluids containing oocytes that became fertilized had significantly higher levels of 20 alpha-dihydroprogesterone and progesterone and lower levels of androstenedione. Of all the steroids determined, 20 alpha-dihydroprogesterone provides the most significant group differences. Enhanced 20 alpha-dihydrogenation in the presence of decreased 16 alpha- and 17-hydroxylation appears to be an important characteristic of the ultimate ripening stages and early luteinization, at least in stimulated cycles.

Effects of leuprolide acetate on follicular fluid hormone composition at oocyte retrieval for in vitro fertilization

The follicular fluid (FF) in 91 follicles from 17 women treated with leuprolide acetate (LA) before stimulation with gonadotropins for in vitro fertilization were analyzed for estradiol (E2), progesterone (P), androstenedione, prolactin, and human chorionic gonadotropin (hCG) and compared with the concentrations in 128 follicles from 31 women treated with gonadotropins alone. The FF E2 concentration in LA-treated patients was significantly lower than in non-LA patients for all oocyte maturational stages. Follicles containing metaphase II oocytes had significantly lower concentrations of P and hCG in LA-treated patients. These differences persisted when analysis was limited to follicles whose oocytes fertilized normally. These data indicate that in the presence of LA, normal oocyte maturation can occur despite lower intrafollicular concentrations of E2 and P.

The effect of prolactin on murine in vitro fertilization and embryo development

Elevated levels of serum and follicular fluid prolactin occur in women undergoing ovulation induction with both clomiphene citrate and gonadotropin therapy. Prolactin's effect on oocyte fertilization and embryo cleavage has not been fully characterized. Using a murine model, we investigated the effect of prolactin on in vitro fertilization and subsequent embryo cleavage in media containing 150, 400, and 600 ng/ml purified mouse prolactin. No difference was found in fertilization rates when compared with control rates. Culture of both in vivo and in vitro fertilized two-cell embryos in murine prolactin at 150, 400, and 600 ng/ml showed no significant difference in blastocyst, morula, or embryo degeneration rates when compared with control rates. An assay for binding of murine prolactin to spermatozoa, oocytes, and the embryo at various cleavage stages revealed no specific murine prolactin binding. These in vitro experimental results fail to show a role for murine prolactin in effecting mature oocyte fertilization or subsequent embryo cleavage. The lack of binding of murine prolactin to the gametes and early developing embryo supports the in vitro findings.

Preovulatory follicular fluid: relationships to ovarian stimulation protocol, fertilization, and sperm penetration in vitro

Sixty follicular fluids were aspirated from 21 patients undergoing in vitro fertilization. Twelve patients (30 follicles) were stimulated with follicular phase gonadotropin-releasing hormone-agonist (GnRH-a) and gonadotropins and 9 (30 follicles) were given clomiphene citrate (CC) and gonadotropins. Significantly higher progesterone (P), P/estradiol (E2) ratios and lower E2, luteinizing hormone (LH), and human chorionic gonadotropin levels were found in the follicles of patients given GnRH-a compared with CC. Preovulatory plasma LH, P, and E2 were lower in the GnRH-a group but these comparisons were not significant. Fertilization rates were similar in the two treatment groups and no differences were found between fluids yielding fertilized or unfertilized oocytes. Sperm penetration into the zona pellucida was unrelated to follicular components. Possible physiological explanations are discussed.

Bromocriptine inhibition of anesthesia-induced hyperprolactinemia: effect on serum and follicular fluid hormones, oocyte fertilization, and embryo cleavage rates during in vitro fertilization

Thirty-two patients undergoing in vitro fertilization (IVF) were given bromocriptine either 1 or 12 hours before anesthesia or received no drug to determine what effect suppression of transient, anesthesia-induced hyperprolactinemia would have on peripheral and follicular fluid hormones, fertilization and cleavage rates, and pregnancy. Thirty minutes after anesthesia, there was a 120-ng/mL rise in serum prolactin (PRL) in control patients versus an insignificant change in women given bromocriptine. Levels of PRL in follicular fluid were significantly less, and estradiol (E2) levels were higher (P less than 0.05) in all bromocriptine-treated patients compared with controls, whereas follicular fluid levels of progesterone (P), inhibin activity, and midluteal serum P were unaffected. Although fertilization and pregnancy rates were similar, a greater proportion of fertilized oocytes from bromocriptine-treated patients advanced to cleaving embryos compared with controls (95% versus 63%, respectively; P less than 0.001). We conclude that bromocriptine, given before anesthesia, can suppress transient, anesthesia-induced hyperprolactinemia and dramatically alter follicular fluid concentrations of PRL and E2. Although these changes in hormonal milieu affected neither oocyte fertilization nor pregnancy rate in our IVF patients, they seemed to have a positive influence on embryonic development after IVF.

Follicular fluid steroid content and in vitro steroid secretion by granulosa-lutein cells from individual follicles among different stimulation protocols for in vitro fertilization-embryo transfer

The in vitro steroidogenic capacity of granulosa-lutein (G-L) cells aspirated from individual follicles during cycles of in vitro fertilization-embryo transfer was examined and compared among three different stimulation protocols: human menopausal gonadotropins (hMG), clomiphene citrate (CC) and hMG, and follicle stimulating hormone (FSH). In addition, the clinical outcome of the patients in each protocol was examined. After 3 days of culture in basal medium, fresh medium with or without androstenedione (A) (10(-7) M) was added for 24 hr, at which time medium was obtained for measurement of progesterone (P) and estradiol (E) content. Follicular fluid (FF) P, E, and A were measured in each follicle and compared among protocols. FF from individual follicles in patients stimulated with FSH contained higher levels of P compared to FF from patients stimulated with hMG or CC/hMG, while E was higher in patients stimulated with CC/hMG compared to FSH or hMG. FF levels of A were not significantly different among the protocols. In vitro steroid secretion revealed a progressive increase in P secretion in contrast to decreasing E secretion when one compares CC/hMG, hMG, and FSH. Patients undergoing ovarian hyperstimulation with FSH had significantly more atretic oocytes identified at the time of oocyte harvest compared to patients undergoing ovarian hyperstimulation with CC/hMG or hMG. The hMG protocol yielded significantly fewer fertilized oocytes, cleaved embryos, and transferred embryos, compared to the CC/hMG and FSH protocol, however, there was no significant difference in pregnancy rate among the three protocols. These data demonstrate that individual follicles contain G-L cells with markedly different abilities to luteinize in vitro as assessed by steroid secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of prolactin during preincubation of mouse spermatozoa on fertilizing capacity in vitro

In the present study, some beneficial effects of mouse prolactin (PRL) on spermatozoa were demonstrated in mice. The motility rate of spermatozoa is well maintained during incubation in modified Krebs-Ringer bicarbonate solution (mKRB) containing PRL (10 or 100 ng/ml) for up to 120 min. When spermatozoa that had been preincubated in the same PRL-containing mKRB were incubated with oocytes in mKRB, significantly more spermatozoa attached to the zona pellucida of each oocyte. When spermatozoa that had been preincubated in mKRB with PRL (50 and 100 ng/ml) for only 15 or 30 min were used for in vitro fertilization (IVF), significantly higher fertilization rates were yielded by those spermatozoa than by control spermatozoa preincubated without PRL for the same periods. The prolongation of the preincubation period did not result in increased fertilization rates. Thus, PRL demonstrated biological effects on spermatozoa by shortening the optimal preincubation period for spermatozoa to acquire capacitation and by maintaining their motility and ability of the attachment to the oocyte during IVF. The results are relevant to clinical application of PRL for infertile patients with oligozoospermia or asthenozoospermia.

Human follicular fluid: prolactin is biologically active and ovum fertilization correlates with estradiol concentration

The bioactivity of prolactin (PRL) in follicular fluid (FF) obtained from mature preovulatory follicles was measured by the Nb2 lymphoma-cell bioassay and compared with the immunoreactivity as measured by radioimmunoassay (RIA-PRL). There was a good correlation between the two assay systems (P less than 0.01), and when RIA-PRL was more than 25 ng/ml, both assay systems yielded comparable values, with a mean bioassay/RIA ratio of 1.06 +/- 0.03; however, when RIA-PRL was 25 ng/ml or less, a discrepancy between the two assay systems was evident, with a bioassay/RIA ratio of 1.55 +/- 0.15. The estradiol (E2) concentration of FF obtained from follicles that contained oocytes which were subsequently fertilized was greater than that in follicles containing oocytes which were not fertilized: 588 +/- 62 vs 376 +/- 37 ng/ml (P less than 0.01), respectively. No differences were found in bioassay-PRL, RIA-PRL, progesterone (P), and FF volumes between fertilized and unfertilized groups of follicles. FF from mature preovulatory follicles contained greater concentrations of RIA-PRL compared to immature follicles (34.6 +/- 3.1 vs 8.5 +/- 1.6 ng/ml; P less than 0.001).

Intraovarian markers of follicular and oocyte maturation

The use of ovulation induction for multiple follicular growth in in vitro fertilization (IVF) has introduced the problem of follicular asynchrony. As a consequence of the asynchrony, the parameters most commonly used by IVF groups to assess follicular and oocyte quality within those follicles are not sufficiently sensitive or specific. Thus, each follicle must be considered separately, and specific markers of follicular and/or oocyte maturation must be sought from within the follicle. In this review we analyze previous reports of potential markers of follicular and oocyte maturation. In regards to the follicular fluid constituents, the level of estradiol in follicular fluid correlates with fertilization and pregnancy in stimulated cycles. Other steroids are only helpful when specific stimulation protocols are used. The level of some follicular proteins such as alpha-1-antitrypsin and fibrinogen also correlates with fertilization and pregnancy outcome. Cyclic AMP levels in follicular fluid are significantly reduced in follicles leading to conception. Regulators of oocyte maturation, such as the Oocyte Maturation Inhibitor (OMI) or the Meiosis Inducing Substance (MIS) have also been correlated with IVF outcome, but their exact structure remains still unknown. In addition, other sophisticated parameters, such as chemotactic activity of human leukocytes, or simple methods, such as the presence of intrafollicular echoes, have also been used as successful markers in predicting IVF outcome.