Caspase-3 gene expression in human luteinized granulosa cells is inversely correlated with the number of oocytes retrieved after controlled ovarian stimulation.

Granulosa cells control oocyte maturation through paracrine signalling and changes to the microenvironment around the oocyte. Apoptosis occurs as a physiological mechanism of granulosa cell renewal, but how it relates with the ovarian response to induced ovulation is still unclear. Therefore, this study evaluated apoptosis-related gene expression levels in granulosa cells of patients undergoing controlled ovarian stimulation. We enrolled prospectively 59 consecutive IVF patients referred to a tertiary academic hospital for couple infertility treatment. Luteinized granulosa cells were isolated from follicular fluid and the RNA was extracted, reverse-transcribed and the gene expression of apoptosis inducers (caspase-3, caspase-8 and bax) and inhibitor (Bcl-2) was quantified by real-time polymerase chain reaction. Caspase-3 gene expression correlated negatively with the number of pre-ovulatory follicles (Spearman's r = -0.308), the number of collected oocytes (r = -0.451), the number of mature oocytes (r = -0.526), the number of fertilized oocytes (r = -0.439) and the number of viable embryos (r = -0.443, all statistically significant at p < 0.02 level). No such associations were found with caspase-8, bax or bcl-2. These preliminary findings suggest that increased caspase-3 gene expression in granulosa cells is associated with a worse ovulatory response in humans.

Prolonged injectable formulation of Nafarelin using in situ gel combination delivery system.

The principal purpose of the present study was to prepare and characterize a complex drug delivery system consisting of Nafarelin-poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanoparticles (NPs) in combination with sodium alginate/poloxamer 407 in situ gel. Nafarelin-loaded PHBV NPs were prepared via double emulsion solvent evaporation technique. Box-Behnken Response Surface Methodology was utilized to optimize NPs. Mean particle size, polydispersity index (PDI), entrapment efficiency (EE), and drug loading (DL) of the optimized NPs were measured. Incorporation of Nafarelin within NPs was proven by differential scanning calorimetry (DSC). The combination delivery system (CDS) was prepared by adding Nafarelin-loaded PHBV NPs to sodium alginate/poloxamer 407 solution followed by physical mixing. Morphological properties of Nafarelin-loaded PHBV NPs and CDS were evaluated by SEM. Rheological properties were employed to investigate the effects of alginate concentration on sol-gel transition temperature. The release profile of Nafarelin from both PHBV NPs and CDS were individually assessed. The cumulative release percentage from CDS was significantly lower than Nafarelin released from PHBV NPs. Based on the favorable results in this study, the CDS consisting of sodium alginate/poloxamer 407 loaded with PHBV NPs could be a promising candidate for designing a long-lasting formulation of Nafarelin.

Intranasal gonadotropin-releasing hormone agonist (GnRHa) for luteal-phase support following GnRHa triggering, a novel approach to avoid ovarian hyperstimulation syndrome in high responders.

OBJECTIVE: To study whether intranasal GnRH agonist (GnRHa) can be effectively used for luteal support in high-responder patients undergoing fresh-embryo transfer after ovulation induction with the use of GnRHa. DESIGN: Retrospective cohort study. SETTING: Private fertility clinic. PATIENT(S): Forty-six high-responder patients were administered a GnRHa ovulation trigger to avoid ovarian hyperstimulation syndrome (OHSS), followed by 2 weeks of daily intranasal GnRHa (nafarelin) for luteal-phase support. No additional progesterone supplementation was administrated. INTERVENTION(S): Intranasal GnRHa for luteal-phase support. MAIN OUTCOME MEASURE(S): The primary outcome was ongoing clinical pregnancy rate. RESULT(S): High median progesterone levels were measured at midluteal phase and on the day of the first positive pregnancy test (190 nmol/L on both measures). We obtained 24 (52.1%) ongoing clinical pregnancies. None of the patients developed OHSS. CONCLUSION(S): Intranasal GnRHa is effective in achieving luteal-phase support in high-responder patients triggered with GnRHa and avoiding OHSS.

p27 and its ubiquitin ligase Skp2 expression in endometrium of IVF patients with repeated hormonal stimulation.

This preliminary study examined a possible effect of long duration repeated hormonal stimulation on the endometrium using a molecular tool. The expression of the hormone stimulated, cell cycle regulators, p27 and its ligase S-phase kinase-interacting protein2 (Skp2), were assessed in 46 endometrial samples of patients who underwent repeated IVF cycles (3-21). Skp2 protein is usually undetectable in normal tissue and can be demonstrated only in rapidly dividing cells. Samples from non-stimulated, normal cycling women served as control group A. Samples of endometrial carcinoma served as control group B. In secretory endometrium, the expression of p27 was found to be lower and Skp2 higher in the study group compared with control group A. Moreover, in 25% of patients of the study group, Skp2 expression was significantly higher (P < 0.05) compared with control group A, reaching concentrations demonstrated in endometrial carcinoma. The findings of this study suggest that repeated hormone stimulation cycles may disrupt endometrial physiology, potentially towards abnormal proliferation. These changes in protein expression are described for the first time in IVF patients and should be further investigated.

GnRH agonist trigger and a freeze-all strategy to prevent ovarian hyperstimulation syndrome: a retrospective study of OHSS risk and pregnancy rates.

AIMS: To analyse the data from all controlled ovarian hyperstimulation antagonist cycles that used an agonist trigger and a freeze-all strategy to quantify the risk of ovarian hyperstimulation syndrome (OHSS) and subsequent pregnancy rates. MATERIALS AND METHODS: A retrospective study of all women attending fertility clinics at IVF Australia, Sydney, undergoing controlled ovarian hyperstimulation (COH) using an antagonist protocol that had a subsequent gonadotropin-releasing hormone (GnRH) agonist trigger and freezing of all oocytes or embryos. The primary outcome measure was to determine the rate of OHSS. The secondary outcome measure was the clinical pregnancy rate. RESULTS: We collected data for 123 women. 25.2% were undergoing oocyte freezing and 74.8% underwent embryo freezing. There were no cases of OHSS, either early or late onset. The pregnancy rate was 31.7% after the first frozen cycle transfer with a cumulative pregnancy rate of 50% after two frozen embryo transfers. CONCLUSION: Our results support the hypothesis that a GnRH agonist trigger and a freeze-all approach prevents OHSS with a good pregnancy rate.

Long gonadotropin-releasing hormone agonist versus short agonist versus antagonist regimens in poor responders undergoing in vitro fertilization: a randomized controlled trial.

OBJECTIVE: To compare the efficacy of the long GnRH agonist vs. the short GnRH agonist vs. the GnRH antagonist regimens in poor responders undergoing IVF. DESIGN: Randomized controlled trial. SETTING: Tertiary referral fertility units. PATIENT(S): Women with previous poor ovarian response undergoing IVF. INTERVENTION(S): One hundred eleven women were randomized to the long GnRH agonist, short agonist, and antagonist regimens. MAIN OUTCOME MEASURE(S): The primary outcome was the number of oocytes retrieved. Secondary outcome measures were gonadotropin consumption, duration of stimulation, cycle cancellation rate, mature oocytes retrieved, fertilization rate, cycles reaching ET, and clinical and ongoing pregnancy rates. RESULT(S): Number of oocytes retrieved was significantly higher with long GnRH agonist compared with the short agonist regimen (4.42 ± 3.06 vs. 2.71 ± 1.60), while there was no significant difference between long agonist and antagonist regimens (4.42 ± 3.06 vs. 3.30 ± 2.91). Duration of stimulation and total gonadotropin dose were significantly higher with long agonist compared with short agonist and antagonist regimens. The ongoing pregnancy rate was 8.1% with long and short agonist regimens and 16.2% with the antagonist regimen. CONCLUSION(S): Long GnRH agonist and antagonist regimens offer a suitable choice for poor responders, whereas the short agonist regimen may be less effective because of fewer eggs retrieved.

Using the ovarian sensitivity index to define poor, normal, and high response after controlled ovarian hyperstimulation in the long gonadotropin-releasing hormone-agonist protocol: suggestions for a new principle to solve an old problem.

OBJECTIVE: To explore the utility of using the ratio between oocyte yield and total dose of FSH, i.e., the ovarian sensitivity index (OSI), to define ovarian response patterns. DESIGN: Retrospective cross-sectional study. SETTING: University-affiliated private center. PATIENT(S): The entire unselected cohort of 7,520 IVF/intracytoplasmic sperm injection treatments (oocyte pick-ups [OPUs]) during an 8-year period (long GnRH agonist-recombinant FSH protocol). INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): The distribution of the OSI (oocytes recovered × 1,000/total dose of FSH), the cutoff levels for poor and high response, set at ±1 SD, and the relationship between OSI and treatment outcome. RESULT(S): OSI showed a log-normal distribution with cutoff levels for poor and high response at 1.697/IU and 10.07/IU, respectively. A nomogram is presented. Live-birth rates per OPU were 10.5 ± 0.1%, 26.9 ± 0.6%, and 36.0 ± 1.4% for poor, normal, and high response treatments, respectively. The predictive power (C-statistic) for OSI to predict live birth was superior to that of oocyte yield. CONCLUSION(S): The OSI improves the definition of ovarian response patterns because it takes into account the degree of stimulation. The nomogram presents evidence-based cutoff levels for poor, normal, and high response and could be used for unifying study designs involving ovarian response patterns.

Evaluation of drug interactions with nanofibrillar cellulose.

Nanofibrillar cellulose (NFC) (also referred to as cellulose nanofibers, nanocellulose, microfibrillated, or nanofibrillated cellulose) has recently gotten wide attention in various research areas and it has also been studied as excipient in formulation of the pharmaceutical dosage forms. Here, we have evaluated the interactions between NFC and the model drugs of different structural characteristics (size, charge, etc.). The series of permeation studies were utilized to evaluate the ability of the drugs in solution to diffuse through the thin, porous, dry NFC films. An incubation method was used to determine capacity of binding of chosen model drugs to NFC as well as isothermal titration calorimetry (ITC) to study thermodynamics of the binding process. A genetically engineered fusion protein carrying double cellulose binding domain was used as a positive control since its affinity and capacity of binding for NFC have already been reported. The permeation studies revealed the size dependent diffusion rate of the model drugs through the NFC films. The results of both binding and ITC studies showed that the studied drugs bind to the NFC material and indicated the pH dependence of the binding and electrostatic forces as the main mechanism.

A mathematical model of the human menstrual cycle for the administration of GnRH analogues.

The paper presents a differential equation model for the feedback mechanisms between gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), development of follicles and corpus luteum, and the production of estradiol (E2), progesterone (P4), inhibin A (IhA), and inhibin B (IhB) during the female menstrual cycle. Compared to earlier human cycle models, there are three important differences: The model presented here (a) does not involve any delay equations, (b) is based on a deterministic modeling of the GnRH pulse pattern, and (c) contains less differential equations and less parameters. These differences allow for a faster simulation and parameter identification. The focus is on modeling GnRH-receptor binding, in particular, by inclusion of a pharmacokinetic/pharmacodynamic (PK/PD) model for a GnRH agonist, Nafarelin, and a GnRH antagonist, Cetrorelix, into the menstrual cycle model. The final mathematical model describes the hormone profiles (LH, FSH, P4, E2) throughout the menstrual cycle of 12 healthy women. It correctly predicts hormonal changes following single and multiple dose administration of Nafarelin or Cetrorelix at different stages in the cycle.

Validation of LC-MS/MS Method for Determination of Bivalirudin in Human Plasma: Application to a Pharmacokinetic Study

BACKGROUND: Bivalirudin is a direct thrombin inhibitor for patients with unstable angina undergoing percutaneous coronary intervention. METHODS: A sensitive liquid chromatography-tandem mass spectrometry (LC/MS/MS) method was developed and validated for the determination of bivalirudin, in human plasma using nafarelin as internal standard (IS). Chromatographic separation was performed using a Shiseido MG3 mm column (2.0 x 50 mm) with a gradient mobile phase consisting of water and acetonitrile containing 0.1 % formic acid at a flow rate of 0.4 mL/min, and total run time was within 5 min. Detection and quantification was performed by the mass spectrometer using a multiple reaction-monitoring mode at m/z 1091.0 --> 650.3 for bivalirudin, and m/z 662.1 --> 249.3 for IS. RESULTS: The assay was linear over a concentration range of 10 - 10000 ng/mL with a lower limit of quantification of 10 ng/mL in human plasma. CONCLUSION: This method was successfully applied for pharmacokinetics study after intravenous administration of bivalirudin to healthy Korean male volunteers.

Restart of steroidogenesis in dogs during recrudescence of testicular function following downregulation with a GnRH-agonist implant.

To date, no details are available concerning the restart of steroidogenesis following the downregulation of testicular endocrine and germinative function by gonadotrophin-releasing hormone (GnRH)-agonist implants. This restart was assessed by determining the expression of steroidogenic acute regulatory (StAR) protein, cytochrome P450 side-chain cleavage enzyme (P450scc) and cytochrome P450 17α-hydroxylase,17,20-lyase (P450c17). The re-establishment of steroidogenesis was initiated by the removal of the GnRH-agonist implant (18.5 mg azagly nafarelin, Gonazon) at 5 months after treatment. Testes were removed at 3-week intervals (weeks 0-24) and four groups were formed according to the stage of spermatogenesis as revealed by the most developed germ cells observed (developmental group [DG] spermatocytes to DG elongated spermatids). Five dogs served as untreated controls. Positive immunostaining for StAR, P450scc and P450c17 was restricted to Leydig cells. Western blot indicated the specifity of the respective antibodies with hints of a expression of canine-specific P450scc and P450c17 proteins. A significant effect of group was observed for a percentage of the immunopositive area (PIA) as an indicator of active Leydig cells for StAR (P<0.05), P450scc (P<0.001) and P450c17 (P<0.001), with PIA being lowest for the DG spermatocytes. With regard to the strength of the immunopositive signal, a significant effect of group was found for P450scc (P<0.01) and P450c17 (P<0.05), with the lowest intensity being observed in DG spermatocytes. At the mRNA level, the upregulation from DG spermatocytes to DG round spermatids was clearly evident but was only significant for P450scc (P<0.05). Thus, downregulation affects the whole cascade of steroidogenesis, whereas withdrawal of inhibition results in a rapid restart, in part indicating a rebound phenomenon.

Development of semen quality following reversible downregulation of testicular function in male dogs with a GnRH agonist implant.

Slow-release GnRH agonist implants have shown to be an effective and reversible alternative to surgical castration. Testicular function is downregulated with an arrest of spermatogenesis on the level of spermatogonia/primary spermatocytes but is fully restored after abolition of downregulation. Aim of this study was to assess the quality of ejaculates after active abolishment of downregulation by implant removal and to follow recrudescence of spermatogenesis. Five dogs - which served as their own controls - were treated with a slow-release implant containing the GnRH agonist azagly-nafarelin. Implants were removed during full downregulation (testosterone <0.1 ng/ml), and attempts to collect ejaculates started from week 4 onwards to week 29. First ejaculates could be obtained between weeks 8 and 12 with the first fully elongated spermatozoa observed in week 10. Volume, %motility and total sperm count increased and %pathomorphology decreased during the course of the study with all ejaculates being in the normal range by week 29. Our data indicate that onset of recrudescence of spermatogenesis coincides with the first testosterone increase after active abolishment of downregulation. Semen quality was fully regained with a significant improvement of %pathomorphology (p < 0.05) and a tendency of improved %motility. However, these observations on an improved semen quality need further validation and no final conclusions can be drawn yet.

Elevated progesterone in GnRH agonist down regulated in vitro fertilisation (IVFICSI) cycles reduces live birth rates but not embryo quality.

OBJECTIVE: To assess the impact of pre-hCG elevated progesterone on live birth outcomes during GnRH agonist long down regulated protocol assisted reproduction cycles. DESIGN: Retrospective cohort study. SETTING: Single Centre Private IVF Clinic. PATIENTS: A total of 582 consecutive cycles of IVF/ICSI in 2003. INTERVENTIONS: All patients underwent a long down-regulation protocol, controlled ovarian stimulation and IVF/ICSI. Serum progesterone concentrations were measured just prior to HCG administration. 253 patients were followed to 2009 for outcomes of their frozen embryo cycles. MAIN OUTCOME MEASURE: Live birth rate in fresh and frozen cycles. RESULTS: Patients in the upper quartile pre-hCG progesterone concentration (≥ 5.4 pmol/L) had a higher final estradiol level, more oocytes collected and more usable embryos, when compared to those with lower quartiles. They also had lower live birth rates per cycle started (21.9% vs. 15%, P < 0.05). However, live birth rates from frozen embryo cycles were not significantly different between the groups. CONCLUSIONS: Pre-hCG progesterone elevation leads to lower live birth rates in stimulated IVF cycles. Live birth rates achieved with frozen embryos in the high progesterone cycles suggest, that pre-hCG progesterone elevation negatively affects endometrial receptivity without adversely affecting embryo quality.

A case of progesterone-induced anaphylaxis, cyclic urticaria/angioedema, and autoimmune dermatitis.

OBJECTIVE: Women have exhibited anaphylaxis, urticaria/angioedema, and autoimmune progesterone dermatitis (APD) coinciding with the progesterone premenstrual rise. We report a detailed immunological evaluation of such a woman responsive to a gonadotropin hormone-releasing agonist (GHRA). METHODS: Skin testing, enzyme-linked immunosorbent assays (ELISAs), leukocyte histamine release (LHR), and inhibition assays were performed to demonstrate progesterone immunoresponsiveness. RESULTS: Serum specific-progesterone immunoglobulin G (IgG) and IgE were detected initially and disappeared 6 months after GHRA treatment. Dose-response LHR using patient basophils was observed for different hormones but after 3 months persisted only for 5ß-pregnanediol. Preincubation with mouse antiprogesterone monoclonal antibody (PmAb) or mifepristone, a progesterone inhibitor, over a range of doses inhibited specific progesterone-induced LHR. Experiments with varying progesterone concentrations and a fixed dose of anti-IgE resulted in 100% LHR at a concentration as low as 0.016 nmol/mL, which, without anti-IgE, failed to release histamine. CONCLUSIONS: This is the first report of combined recurrent anaphylaxis, cyclic urticaria/angioedema, and APD induced by immunoresponsiveness to progesterone.

A randomised controlled trial of 300 versus 225 IU recombinant FSH for ovarian stimulation in predicted normal responders by antral follicle count.

OBJECTIVE: To test the hypothesis that among women predicted to have a normal ovarian response, ovarian stimulation using 300 IU follicle-stimulating hormone (FSH) results in the retrieval of more mature oocytes than 225 IU during in vitro fertilisation (IVF)/intracytoplasmic sperm injection (ICSI) treatment. DESIGN: Prospective randomised controlled study. SETTING: University-based assisted conception unit. POPULATION: A cohort of 131 women predicted to have a normal ovarian response to gonadotrophin stimulation, based on antral follicle count. METHODS: Subjects undergoing their first cycle of IVF/ICSI were randomised to receive a fixed daily dose of 300 (experimental arm) or 225 IU (control arm) of recombinant FSH (Gonal-F). MAIN OUTCOME MEASURES: Number of mature oocytes retrieved and live birth rates. RESULTS: The number (mean +/- standard deviation) of mature oocytes retrieved (8.2 +/- 5.0 versus 9.0 +/- 4.8, for 300 and 225 IU, respectively; P = 0.34) was similar in each group. There were no differences between the 300- and 225 IU arms in live birth rates (31 versus 41%, respectively; P = 0.25), cycle cancellations resulting from insufficient ovarian response (0 versus 6.1%, respectively; P = 0.12), and prevalence of moderate (3.1 versus 3.0, respectively; P = 1.0) and severe (0 versus 1.5%, respectively; P = 1.0) ovarian hyperstimulation syndrome. CONCLUSIONS: The use of a higher daily dose of 300 IU of recombinant FSH for ovarian stimulation does not improve the number of mature oocytes retrieved, or live birth rates, among women with a predicted normal response during conventional IVF/ICSI.

Evaluation of the clinical efficacy of Gonazon implants in the treatment of reproductive pathologies, behavioral problems, and suppression of reproductive function in the male dog.

Efficacy of a slow-release gonadotropin-releasing hormone (GnRH)-agonist implant (Gonazon) was assessed in 53 male dogs presented with benign prostatic hyperplasia (BPH), hypersexuality, aggressive behavior (either alone or in combination), excessive micturition, or to suppress fertility. Changes in testosterone (T) and estradiol (E2) concentrations and size of testes and prostate were monitored on Weeks 0, +8, and +26 after implantation. Additional measurements during and after this period were performed in 35 dogs. Clinical signs were assessed by the owners. All implants except one were retained throughout the study. Full downregulation of testicular function (T<0.35 nmol/L) was achieved in 46 dogs, five dogs showed partial downregulation (T = 0.36 to 0.47 nmol/L), one dog did not respond, and another one displayed a transient downregulation on Week +18. On Week +8, mean T and E2 levels were reduced by 96% and 62%, respectively, and did not further decrease. Full downregulation (T<0.35 nmol/L) lasted between 6 to >22 mo in most dogs except two. Compared with pretreatment values, mean testicular and prostatic size was reduced (P<0.00001) by 54% and 52%, respectively, on Week +8 and by 68% and 64%, respectively, on Week +26. Relative reduction of prostatic size was more marked in dogs with BPH than in healthy ones on Week +8 (P<0.05) and Week +26 (P<0.02), and clinical signs of BPH disappeared rapidly after implantation. Dogs affected with BPH were significantly older (P<0.001) than nonaffected ones (9.7 vs. 2.5 yr). Hypersexuality was more common in dogs<3 yr of age, and treatment clearly improved clinical signs. Age significantly affected the response to treatment in aggressive dogs; 75% of the cases responded with an improvement. The only minor and possibly treatment-related events observed were a short-lasting exacerbation of clinical signs of BPH (two dogs), increased weight gain (three dogs), and anxiety (three dogs) with one of these dogs developing a blunt coat. These results demonstrate the clinical efficacy and overall safety of the Gonazon implants.

Sterile abscess formation in response to two separate branded long-acting gonadotropin-releasing hormone agonists.

BACKGROUND: Long-acting forms of gonadotropin-releasing hormone (GnRH) receptor agonists are commonly used for the treatment of central precocious puberty (CPP). Sterile abscess formation has been reported as a complication of leuprolide acetate, but not histrelin acetate. OBJECTIVE: The aim of this study was to report an adverse drug reaction in a child with sterile abscess formation following treatment with 2 different branded long-acting forms of GnRH agonists. CASE SUMMARY: An otherwise healthy 8-year-old white female (weight, 40.7 kg; height, 140.1 cm) with documented CPP and no known drug allergies developed a sterile abscess at the site of the monthly intramuscular injection of 15 mg of leuprolide acetate. Because of this site reaction, a 50-mg histrelin acetate insert was placed in the patient's left arm. A similar reaction occurred 2 weeks after insert placement on 2 separate occasions in different arms. At the time of the removal of the second insert, Gram stain and swab culture of the purulent wound discharge were negative. The child was subsequently treated with intranasal nafarelin (800 ug twice daily) and tolerated it well. The Naranjo Adverse Drug Reaction Causality Score was 10 (definite, ≥9). CONCLUSION: This report describes a case of sterile abscess formation definitely associated with 2 different forms of long-acting GnRH agonist treatment in a child.

Controlled delivery of a GnRH agonist by a silastic implant (Gonazon) results in long-term contraception in queens.

Many female cats are spayed to prevent problems associated with calling and unwanted pregnancies. This study describes the safety and efficacy of an alternative approach, using an azagly-nafarelin containing implant (Gonazon) inserted subcutaneously in the neck of six treated queens for 3 years. These six queens together with six controls were permanently housed with vasectomized tom cats, and changes in progesterone concentrations were used to document the contraceptive efficacy of Gonazon. All six control queens ovulated regularly throughout the treatment period (3 years), as shown by regular changes in progesterone concentration. Sixteen ovulatory cycles were observed in each control throughout the study. In Gonazon treated queens, during the week following implant placement, two queens displayed a treatment-induced rise in progesterone concentration. Later on, all treated queens continuously displayed low progesterone concentrations until 3 years post-implant insertion, with the exception of a single isolated episode (at approximately 2.5 years of treatment), of follicular luteinization in two queens. In all queens, azagly-nafarelin concentrations peaked in the week following implant insertion remained high for 1 month and later decreased slowly. After 2.5 years of treatment, azagly-nafarelin concentrations were still greater than 150 pg/ml in 3/6 queens. During a 6-month long extension of the study (36-42 months post-treatment), all queens (treated and controls) were run with intact tom cats. None of them conceived. Following autopsy, ovarian weight and diameter of the uterine horns of 3/6 treated queens were shown to be similar to those of the controls. In conclusion, this study demonstrated that Gonazon efficiently prevented ovulation in queens (100%) for 3 years. Return to fertile heat was not observed towards the end of treatment. However, in half of the treated queens, reversibility of the treatment induced effects on the genital tract was demonstrated.