Poor oocyte retrieval is a manifestation of low ovarian reserve

Mixed effects of ambient air pollutants on oocyte-related outcomes: A novel insight from women undergoing assisted reproductive technology

Air pollution is widely acknowledged as a significant risk factor for human health, especially reproductive health. Nevertheless, many studies have disregarded the potentially mixed effects of air pollutants on reproductive outcomes. We performed a retrospective cohort study involving 8048 women with 9445 cycles undergoing In Vitro Fertilization (IVF) and Intracytoplasmic Sperm Injection (ICSI) in China, from 2017 to 2021. A land-use random forest model was applied to estimate daily residential exposure to air pollutants, including sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), ozone (O3), and fine particulate matter (PM2.5). Individual and joint associations between air pollutants and oocyte-related outcomes of ART were evaluated. In 90 days prior to oocyte pick-up to oocyte pick-up (period A), NO2, O3 and CO was negatively associated with total oocyte yield. In the 90 days prior to oocyte pick-up to start of gonadotropin medication (Gn start, period B), there was a negative dose-dependent association of exposure to five air pollutants with total oocyte yield and mature oocyte yield. In Qgcomp analysis, increasing the multiple air pollutants mixtures by one quartile was related to reducing the number of oocyte pick-ups by -2.00 % (95 %CI: -2.78 %, -1.22 %) in period A, -2.62 % (95 %CI: -3.40 %, -1.84 %) in period B, and -0.98 % (95 %CI: -1.75 %, -0.21 %) in period C. During period B, a 1-unit increase in the WQS index of multiple air pollutants exposure was associated with fewer number of total oocyte (-1.27 %, 95 %CI: -2.16 %, -0.36 %) and mature oocyte (-1.42 %, 95 %CI: -2.41 %, -0.43 %). O3 and NO2 were major contributors with adverse effects on the mixed associations. Additionally, period B appears to be the susceptible window. Our study implies that exposure to air pollution adversely affects oocyte-related outcomes, which raises concerns about the potential adverse impact of air pollution on women's reproductive health.

Confrontment and solution to gonadotropin resistance and low oocyte retrieval in in vitro fertilization for type I BPES: a case series with review of literature

Background

FOXL2 mutations in human cause Blepharophimosis, ptosis, and epicanthus inversus syndrome (BPES). While type II BPES solely features eyelid abnormality, type I BPES involves not only eyelid but also ovary, leading to primary ovarian insufficiency (POI) and female infertility. Current mainstream reproductive option for type I BPES is embryo or oocyte donation. Attempts on assisted reproductive technology (ART) aiming biological parenthood in this population were sparse and mostly unsuccessful.

Case presentation

Two Chinese type I BPES patients with low anti-müllerian hormone (AMH) and elevated follicle stimulating hormone (FSH) presented with primary infertility in their early 30s. Genetic studies confirmed two heterozygous duplication mutations that were never reported previously in East Asian populations. They received in vitro fertilization (IVF) treatment and both exhibited resistance to gonadotropin and difficulty in retrieving oocytes in repeated cycles. Doubled to quadrupled total gonadotropin doses were required to awaken follicular response. Patient 1 delivered a baby girl with the same eyelid phenotype and patient 2 had ongoing live intrauterine pregnancy at the time of manuscript submission.

Conclusions

This is the second reported live birth of biological offspring in type I BPES patients, and first success using IVF techniques. It confirmed that ART is difficult but feasible in type I BPES. It further alerts clinicians and genetic counsellors to type female BPES patients with caution in view of the precious and potentially narrowed reproductive window.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13048-021-00900-2.

Antral follicle count, oocyte production and embryonic developmental competence of senescent Nellore (Bos indicus) cows

Information on the follicular population and oocyte quality of cows in the final period of reproductive life is scarce. The present study aimed to compare the antral follicle count (AFC), oocyte production and embryonic developmental competence of young versus long-lived and senescent Bos indicus beef cows. Nellore cows (Bos indicus) were classified into three groups according to age: young (4-9 years, n = 10), long-lived (14-17 years, n = 10) and senescent (17-23 years, n = 10). At a random time in the estrus cycle, the cows received cloprostenol sodium salt (0.5 mg, IM), estradiol benzoate (1 mg, IM) and an intravaginal P4 device (1.4 g). Five days later, the P4 devise was removed and oocyte collection (OPU1) was performed. A second OPU (OPU2) was performed 5 days after the first in order to aspirate only growing follicles. During each OPU, AFC and the number and quality of cumulus-oocyte complexes (COCs) were evaluated. Then, the COCs were placed in standard maturation medium (IVM), fertilized and incubated for 9 days. The data were subjected to ANOVA and Multinomial Logistic Regression. The AFC was smaller in long-lived and senescent cows in both OPU1 and OPU2 when compared to younger cows. There was no difference in AFC between OPU1 (19.9 ± 1.8) and OPU2 (17.6 ± 1.9) in young cows, however, more follicles were punctured in long-lived and senescent cows in OPU1 (12.0 ± 2.6 and 19.3 ± 4.6) than in OPU2 (9.2 ± 1.9 and 10.3 ± 2.3), respectively (P < 0.01). The numbers of COCs recovered from young cows (OPU1 = 14.2 ± 1.8; OPU2 = 8.4 ± 0.9) were higher than those obtained from long-lived cows (OPU1 = 5.9 ± 2.3; OPU2 = 4.3 ± 1.0) and senescent cows (OPU1 = 7.2 ± 3.0; OPU2 = 4.1 ± 1.7), respectively (P < 0.05). The cleavage rate did not differ between groups. However, the rate of blastocyst formation was higher for young (64.8%) and long-lived (65.0%) compared to senescent (16.5%) cows (P < 0.01). In conclusion our results indicate that the AFC is lower in long-lived and senescent cows compared with young cows. However, unlike in senescent cows, the embryonic development of long-lived cows is similar to that of young cows. This suggests that Nellore cows aged >17 years begin to have reduced embryonic development capacity due to ovarian aging.

Does the empty follicle syndrome occur in cases of low number of maturing follicles in assisted reproduction?

The pathophysiology of the genuine empty follicle syndrome (EFS) is still debated. Ovarian aging has been contested as a cause of this condition. Our aim was to investigate the occurrence of the genuine EFS in cases of a low number of mature follicles in a prospective manner. Ninety-five infertile women were recruited and evaluated following conventional controlled ovarian stimulation (COS) with ≤ six follicles of ≥14 mm diameter on the day of hCG administration. Enrolled women were 37.5 ± 5.2 years of age with basal FSH level of 9.1 ± 3.7 mIU/L, antral follicle count (AFC) of 6.9 ± 4.6, and number of ≥14 mm follicles (on the day of hCG) of 3.4 ± 1.5. Among the 95 women, four were complicated by the genuine EFS (4.2%) with features of the depleted ovarian reserve. Comparison between these four cases and the 91 controls revealed significant differences between age, AFC, number of ≥14 mm follicles, and serum E₂ level corresponding to 41.8 ± 1.7 versus 37.4 ± 5.2 years, 1.7 ± 0.6 versus 7.1 ± 4.5, 2.0 ± 0.8 versus 3.4 ± 1.5 follicles, and 356 ± 200 versus 975 ± 557 pg/mL, respectively. Post hoc analysis revealed that 56 among the 95 women fulfilled the Bologna criteria for poor ovarian response and all four cases matched the definition of the genuine EFS raising its incidence to 7.1% in this group. A logistic regression analysis showed that AFC was a significant factor in the development of the genuine EFS. We conclude that the genuine EFS complicates infertile women characterized by a low number of mature follicles. Our findings suggest that the mechanism behind this occurrence is associated with a more exhausted ovarian reserve.

Empty Follicle Syndrome: A Challenge to Physician

Background:

Empty follicle syndrome (EFS) is a condition in which no oocytes are retrieved from normally growing ovarian follicles after ovarian stimulation. It is a rare and frustrating condition of obscure etiology.

Objective:

The objective of this study was to estimate the incidence of EFS and study factors related to it.

Design:

This was a retrospective study.

Setting:

This study was conducted in hospital-based research center.

Methods:

In 1968 in vitro fertilization cycles from January 2010 to August 2016 were studied. Agonist, antagonist, and miniflare protocols were used for the stimulation.

Results:

The incidence of EFS is 2.38% (47/1968 cycles). Antagonist protocol group (76.59%, n = 36) had highest incidence of EFS (6.69%). Literature on EFS depicts decreased ovarian reserve (DOR) as the main cause, but only 4.25% of patients had DOR in our study. Interestingly, polycystic ovary syndrome and unexplained infertility were found in 31.9% of the cases. Serum anti-Müllerian hormone (AMH) levels (mean ± standard deviation [SD]) were 4.47 ± 3.54 ng/ml, and antral follicle count (AFC) was 15.30 ± 8.07 (mean ± SD) emphasizing that diminished ovarian reserve is not the main factor for EFS. All patients (n = 95) who underwent ovum pickup on day when any patient had EFS were taken as control. Patients with EFS were compared with controls. A statistically significant difference was not observed in serum AMH (P = 0.38) and AFC (P = 0.52).

Conclusion:

EFS is an uncommon event. Antagonist cycles have higher chances of empty follicle at ovum pickup. Looking at the profile of patients in this study, we conclude that EFS is not a manifestation of DOR.

The "vanishing follicle" in women with low number of developing follicles during assisted reproduction

OBJECTIVE

To investigate the occurrence of the "vanishing follicle" phenomenon in women with low number of developing follicles in assisted reproduction.

STUDY DESIGN

Women with ≤ 6 follicles on the day of hCG administration with ≥ 14mm diameter were prospectively studied. Primary outcome measures were disappearance of ≥14mm and all-diameter follicles on the day of oocyte pick-up compared to the day of hCG administration.

RESULTS

Among the 120 women recruited, 95 were found eligible and completed the study. The "vanishing follicle" phenomenon occurred in 3.1% (95% confidence level: 0.7%-9.0%) and 18.9% (95% confidence level: 11.6%-28.3%) of cases affecting ≥14mm and all-diameter follicles, respectively. In all cases, mid-late follicular serum LH and P levels remained within normal follicular phase range and trans-vaginal scan did not show signs of ovulation. Markedly, the main significant difference between the study and control groups in the ≥14mm follicle group was serum E₂ level on the day of hCG administration; median (Interquartile range), corresponding to 395 (382.0-405.5) versus 823.0 (544.5-1291.0) pg/mL, respectively (P=0.04). The same trend was encountered in all-diameter vanishing follicles group but it did not reach significance. Interestingly, in all-diameter vanishing group, chronic smoking and the P/E₂ ratio on the hCG day were significantly higher than controls. Post hoc multiple logistic regression analysis of data in accordance with the Bologna criteria reveled that antral follicle count was found to significantly affect the development of the "vanishing follicle" phenomenon.

CONCLUSIONS

The "vanishing follicle" phenomenon occasionally occurs in women with low number of developing follicles during assisted reproduction with no signs of ovulation. Our preliminary findings suggest that this phenomenon may be related to exhausted ovarian reserve however, an early-unrecognized LH elevation could not be ruled out.

Dual trigger of final oocyte maturation in poor ovarian responders undergoing IVF/ICSI cycles

Previous studies show that a dual trigger ovulation regimen significantly improves number and maturity of retrieved oocytes for normal ovarian responders or patients with history of low oocyte yield. The current retrospective cohort study investigated whether dual trigger of final oocyte maturation may benefit IVF outcomes for poor ovarian responders fulfilling the Bologna criteria. Undertaken between May 2014 and August 2016, the study involved 1350 patients undergoing 1389 IVF/intracytoplasmic sperm injection treatment cycles. Patients triggered with 5000 IU human chorionic gonadotrophin (HCG) alone (328 cycles) were compared with those undergoing dual triggering with 5000 IU HCG plus 0.1 mg gonadotrophin-releasing hormone agonist (GnRHa) (386 cycles) and patients triggered with 10,000 IU HCG (363 cycles) were compared with those undergoing dual triggering with 10,000 IU HCG plus 0.1 mg GnRHa (312 cycles). The dual trigger groups showed significantly higher number of oocytes collected and number of mature oocytes compared with their respective HCG trigger group (P < 0.001). Oocyte retrieval rate and percentage of mature oocytes retrieved were also both significantly higher in the dual trigger groups (P < 0.001). Fertilization rate, number of viable embryos, implantation rate, clinical pregnancy rate and miscarriage rate were not significantly different between groups.

Low oocyte yield during IVF treatment and the risk of a trisomic pregnancy

A low number of antral follicles may result in the selection of suboptimal oocytes that are prone to meiotic errors. The aim of this case-control study was to evaluate women receiving IVF treatment with low oocyte yield (defined as three or fewer oocytes retrieved after ovarian stimulation) who are at an increased risk of a trisomic pregnancy. Data were obtained from Danish and Dutch medical registries between 1983 and 2011. Analyses were carried out in 105 cases and 442 controls matched by age and year of IVF treatment. Cases were women with a trisomic pregnancy (trisomies 13, 18 or 21) resulting from fresh IVF treatment and confirmed by karyotyping. Cases were included regardless of pregnancy outcome. Controls were women with a live born child without a trisomy, resulting from fresh IVF treatment. Low oocyte yield was observed in 6.6% (29/440) of the women, of which 8.4% (7/83) were cases and 6.2% (22/357) controls. Low oocyte yield in IVF treatment was not associated with a higher risk of trisomic pregnancy (OR 1.43, 95% CI 0.64 to 3.19). Stratification for female age, adjustment for history of ovarian surgery, and gonadotrophin-releasing hormone protocol used did not change the results.

Empty follicle syndrome revisited: definition, incidence, aetiology, early diagnosis and treatment

In this review, the definition, incidence and possible causes of empty follicle syndrome (EFS), including molecular mechanisms that may underlie the syndrome, are discussed, along with prevention and treatment options. EFS is the complete failure to retrieve oocytes after ovarian stimulation, despite apparently normal follicle development and adequate follicular steroidogenesis. Two variants of EFS have been described: the 'genuine' form (gEFS), which occurs in the presence of adequate circulating HCG levels at the time of oocyte aspiration, and the 'false' form (f-EFS), which is associated with circulating HCG below a critical threshold. Heterogeneous HCG concentration thresholds, however, have been used to define gEFS, and to date no standardization exist. The situation is unclear when GnRH-analogues are used for ovulation trigger, as the threshold circulating LH and progesterone levels used to define EFS as 'genuine' are not established. The cause of fEFS has been clearly identified as an error in HCG administration at the time of ovulation trigger; in contrast, the cause of gEFS is still unclear, although some pathogenetic hypotheses have been proposed. Optimal treatment and prognosis of these patients are still poorly understood. Large, systematic multi-centre studies are needed to increase the understanding of EFS.

Empty Follicle Syndrome: The Possible Cause of Occurrence

OBJECTIVES

Empty follicle syndrome (EFS), although rare, is a disappointing condition in which no oocytes are retrieved from mature follicle after ovulation induction in in vitro fertilization (IVF) cycles. The aim of this study was to estimate the incidence and factors associated with EFS.

METHODS

All cycles resulting in EFS from May 2012 to September 2013 were retrospectively identified at a tertiary referral infertility center. Among the 3,356 cycles performed, 58 (1.7%) women who underwent their first IVF cycle and had no oocyte retrieval were enrolled in the study. Three different stimulation protocols (long, antagonist, and miniflare) were mainly used for induction of follicular growth. Data relating to the age, follicle stimulating hormone (FSH) level, anti-Müllerain hormone (AMH) level, and the number of ampules and follicles for each patient was obtained.

RESULTS

Out of 58 individuals, 10 (17.2%) showed false type and 48 (82.8%) showed genuine EFS. The most frequent findings in our study were diminished ovarian reserve, low anti-Müllerian hormone (AMH; ≤0.5 ng/mL), and less than four mature follicles, indicating EFS in 1.7% of the patients.

CONCLUSION

Low serum AMH levels and a small number of follicles after ovarian stimulation is the manifestation of diminished ovarian reserve. Thus, we suggest that EFS could be a manifestation of low ovarian reserve.

Cell-free DNA in Human Follicular Microenvironment: New Prognostic Biomarker to Predict in vitro Fertilization Outcomes

Cell-free DNA (cfDNA) fragments, detected in blood and in other biological fluids, are released from apoptotic and/or necrotic cells. CfDNA is currently used as biomarker for the detection of many diseases such as some cancers and gynecological and obstetrics disorders. In this study, we investigated if cfDNA levels in follicular fluid (FF) samples from in vitro fertilization (IVF) patients, could be related to their ovarian reserve status, controlled ovarian stimulation (COS) protocols and IVF outcomes. Therefore, 117 FF samples were collected from women (n = 117) undergoing IVF/Intra-cytoplasmic sperm injection (ICSI) procedure and cfDNA concentration was quantified by ALU-quantitative PCR. We found that cfDNA level was significantly higher in FF samples from patients with ovarian reserve disorders (low functional ovarian reserve or polycystic ovary syndrome) than from patients with normal ovarian reserve (2.7 ± 2.7 ng/μl versus 1.7 ± 2.3 ng/μl, respectively, p = 0.03). Likewise, FF cfDNA levels were significant more elevated in women who received long ovarian stimulation (> 10 days) or high total dose of gonadotropins (≥ 3000 IU/l) than in women who received short stimulation duration (7–10 days) or total dose of gonadotropins < 3000 IU/l (2.4 ± 2.8 ng/μl versus 1.5 ± 1.9 ng/μl, p = 0.008; 2.2 ± 2.3 ng/μl versus 1.5 ± 2.1 ng/μl, p = 0.01, respectively). Finally, FF cfDNA level was an independent and significant predictive factor for pregnancy outcome (adjusted odds ratio = 0.69 [0.5; 0.96], p = 0.03). In multivariate analysis, the Receiving Operator Curve (ROC) analysis showed that the performance of FF cfDNA in predicting clinical pregnancy reached 0.73 [0.66–0.87] with 88% specificity and 60% sensitivity. CfDNA might constitute a promising biomarker of follicular micro-environment quality which could be used to predict IVF prognosis and to enhance female infertility management.

Predictive factors for oocyte retrieval failure in controlled ovarian hyperstimulation protocols: a retrospective observational cohort study

BACKGROUND

Oocyte retrieval failure following an ovarian hyperstimulation protocol is uncommon in assisted reproductive technology (ART) programs. We analyzed the predictive factors for oocyte retrieval failure following controlled ovarian hyperstimulation (COH) with gonadotropin-releasing hormone (GnRH) agonist and GnRH antagonist protocols in ART programs.

METHODS

This study was a retrospective cohort observational study. In total, 744 cycles from 361 patients who underwent controlled ovarian hyperstimulation with GnRH agonist long protocol or antagonist protocol were analyzed. Treatment cycles with oocyte retrieval failure and with one or more oocytes retrieved were compared to determine predictive factors for oocyte retrieval failure using univariate and multilevel multivariate logistic regression analyses.

RESULTS

Oocyte retrieval failure occurred in 38 cycles (5.1%). The oocyte retrieval failure rate of the GnRH antagonist protocol (8.1%) was significantly higher than that of the GnRH agonist long protocol (3.7%). On multilevel multivariate logistic analysis, cycles with GnRH antagonist protocol (odds ratio [OR] 3.06, 95% confidence interval [CI] 1.05-8.96), estradiol level on the day of human chorionic gonadotropin (hCG) injection (OR 0.997, 95% CI 0.996-0.998), and luteinizing hormone (LH) level on the day of hCG injection (OR 1.19, 95% CI 1.06-1.33) were independent predictive factors for oocyte retrieval failure. The efficacy of estradiol and LH levels on the day of hCG injection for predicting oocyte retrieval failure was evaluated using receiver operating characteristic curves. In all cycles, the areas under the curve (AUCs) for estradiol and LH were 0.84 and 0.63, respectively, for all cycles; 0.84 and 0.52, respectively, for cycles with GnRH agonist long protocol; and 0.81 and 0.82, respectively, for cycles with GnRH antagonist protocol.

CONCLUSIONS

Our results suggest that in cycles with GnRH antagonist protocol, the levels of estradiol and LH on the day of hCG injection might be predictive factors for oocyte retrieval failure. This relationship may provide useful information to both patients and physicians for developing better COH protocols in ART programs.

Empty follicle syndrome

Empty follicle syndrome (EFS) is a condition in which no oocytes are retrieved after an apparently adequate ovarian response to stimulation and meticulous follicular aspiration. EFS can be classified into 'genuine' and 'false' types according to hCG levels. It is a rare condition of obscure etiology. The existence of genuine EFS has been questioned and is still controversial. The limitation around EFS is that the definition of EFS is obscure. Management of patients with EFS is a challenge to physicians. No single treatment is known to be universally effective. However, patients should be adequately informed regarding the importance of correct hCG administration because improper hCG administration is a common and preventable cause of EFS. EFS is a syndrome that deserves additional study because such investigation could lead to a further understanding of ovarian biology and infertility.

Decreased fertility in poor responder women is not related to oocyte morphological status

INTRODUCTION

In women showing impaired fertility, a decreased response to ovarian stimulation is a major problem, limiting the number of oocytes to be used for assisted reproduction techniques (ART). Despite the several definitions of poor response, it is still a matter of debate whether young poor responder patients also show a decrease in oocyte quality. The objective in this study was to investigate whether poor ovarian response to the superstimulation protocol is accompanied by impaired oocyte quality.

MATERIAL AND METHODS

This study included 313 patients younger than 35 years old, undergoing intracytoplasmic sperm injection. Patients with four or fewer MII oocytes (poor-responder group, PR, n = 57) were age-matched with normoresponder patients (NR, n = 256).

RESULTS

A higher rate of oocyte retrieval and a trend towards an increase in MII oocyte rate were observed in the NR group when compared to the PR group (71.6 ±1.1% and 74.1 ±1.0% vs. 56.3 ±2.9% and 66.5 ±3.7%; p< 0.0001 and p = 0.056, respectively). A trend toward increased implantation rates was observed in the NR group when compared to the PR group (44 and 24.5 ±2.0% vs. 28.8 and 16.4 ±3.9%; p= 0.0305 and p= 0.0651, respectively).

CONCLUSIONS

Low response to ovarian stimulation is apparently not related to impaired oocyte quality. However, embryos produced from poor responder oocytes show impaired capacity to implant and to carry a pregnancy to term.

Undetectable basal ovarian stromal blood flow in infertile women is related to low ovarian reserve

To gain insight into the physiological significance of basal ovarian stromal blood flow and to assess whether its detection ability is related to ovarian reserve in infertility patients undergoing in vitro fertilization (IVF) - embryo transfer (ET) treatment. Thirty two consecutive infertile women scheduled for IVF-ET treatment were prospectively evaluated. Basal ovarian hormonal, ovarian volume and stromal blood flow studies were performed on day 3 of a natural cycle before treatment. The performer of the ultrasound studies was blinded to the clinical data. Women in the study were divided into two groups in accordance with estradiol level on the day of administration of human chorionic gonadotropin. Day-3 follicle-stimulating hormone and ovarian volume were significantly poorer in the women with low (group A) as compared with good (group B) ovarian reserve. Likewise, the numbers of follicles > or =14 mm in diameter, oocytes retrieved and embryos achieved were significantly lower in group A than group B. Six clinical pregnancies were obtained in group B, whereas no pregnancy was obtained in group A. Nine out of the 15 (60%) women in group A had undetectable basal stromal blood flow in at least one of the ovaries, whereas only one of the 17 (6%) women in group B had undetectable flow (p < 0.002). Basal stromal peak systolic blood flow velocity, pulsatility index and resistance index mean values did not differ significantly between the two groups. We conclude that undetectable basal ovarian stromal blood flow in at least one ovary is related to low ovarian reserve in infertile women undergoing IVF-ET. It seems that undetectable basal stromal blood flow is not solely a technical issue, but rather linked to the pathophysiology of ovarian aging.

Graft site and gonadotrophin stimulation influences the number and quality of oocytes from murine ovarian tissue grafts

Ovarian tissue cryopreservation and subsequent transplantation can restore fertility in cancer patients. This study used a mouse ovarian grafting model to investigate whether the graft site (bursal cavity, the kidney capsule or subcutaneous) influences the number, fertilization rate and developmental potential of oocytes recovered from grafts and whether using a standard gonadotrophin stimulation protocol would increase oocyte yield from the grafts. Mouse ovarian tissue was grafted into four week old mice and collected three weeks later. Graft recipients were treated either with or without exogenous gonadotrophin stimulation prior to graft collection. Grafted ovaries yielded oocytes that were either at the germinal vesicle (GV) stage or mature metaphase II (MII) stage at collection. These GV oocytes were matured beforein vitrofertilization (IVF), while the MII oocytes underwent IVF immediately. Oocytes collected from the oviducts of non-grafted superovulated mice of the same age served as controls. Two-cell embryos were transferred to pseudopregnant recipients and recovered at day 15 of gestation or left to go to term. Graft retrieval and the number of oocytes from each graft were lowest from the subcutaneous graft site. The number of two-cell embryos produced was significantly higher for oocytes from the grafts to the bursa as compared with the other sites. All graft sites gave rise to embryos with comparable implantation rates and developmental potential to fetuses and offspring following transfer. However, the oocytes from grafted ovaries had a significantly lower developmental potential when compared with the control group. Stimulation with exogenous gonadotrophins did not significantly increase oocyte yield from grafted ovaries but did enhance oocyte maturation and development. In conclusion, graft site affects the number and quality of oocytes produced from ovarian grafts.