Donor sperm insemination after failed intra-couple intracytoplasmic sperm injection.

The purpose of the present multicenter study was to investigate whether an artificial insemination with donor sperm (AID) procedure after intra-couple intracytoplasmic sperm injection (ICSI) failure offers a significant chance of pregnancy and to identify prognostic factors for pregnancy after an AID procedure. An eleven-year retrospective multicenter study was conducted among 13 Centre d'Etude et de Conservation des Oeufs et du Sperme (CECOS) centers. A total of 319 couples having undergone an AID procedure after intra-conjugal ICSI failure were included in this study; a total of 1,159 AID and 1,011 intra-conjugal ICSI cycles were performed. Among the prognostics parameters, the parity and the embryo quality could not be adequately addressed, therefore the parity was not included in the statistical analysis and the embryo quality has been presented as preliminary observations. The pregnancy rate per cycle was 12.0% (139/1,159) and the overall AID pregnancy rate per couple was 43.6% (139/319). Normal or oligoasthenoteratozoospermia (OAT) semen and women aged 34 years or above at the time of AID procedure obtained the lowest AID clinical pregnancy rate. Azoospermia or cryptozoospermia semen and women aged below 34 years obtained the highest AID clinical pregnancy rate. In conclusion, the transition to the AID procedure after intra-conjugal ICSI failure allows such couples to obtain a pregnancy, however after each ART failure AID transition should be proposed according to the woman's age and sperm characteristics. ABBREVIATIONS: AID: artificial insemination with donor sperm; ICSI: intracytoplasmic sperm injection; CECOS: Centre d'Etude et de Conservation des Oeufs et du Sperme; OAT: oligoasthenoteratozoospermia; IVF: in vitro fertilization; ART: artificial reproductive technology; ß hCG: beta human chorionic gonadotrophin; SD: standard deviation; OR: Odds ratio.

An ART score to note objectively the quality of an ART procedure.

OBJECTIVE: To construct an ART score to evaluate an ART procedure before the result (pregnancy or not), and to provide objective data in discussions with couples in the decision to discontinue further attempts. STUDY DESIGN: A retrospective multicentrique study was performed. The ART score was constructed using data from the MediFirst© database used in our center. The development of the score was conducted on a sample of 507 in vitro fertilization cycles carried out between January 2011 and July 2011. Model calibration and determination of the discrimination capacity of the ART score were performed with 4463 cycles in our center and 1369 cycles from an external ART center. The ART score was validated temporally and geographically with clinical pregnancy and take home baby rate. RESULTS: The ART score was obtained from data from both partners and ART procedure. The ART score was segmented into four classes depending on the clinical pregnancy rate. There was a linear relationship between the ART score and clinical pregnancy rate (r = 1.0, p < 0.001). The ART score was validated temporally and geographically. CONCLUSION: An objective ART score has been constructed and validated. It will be of help to ART teams and it is an objective tool to explain to a couple the choices for the next ART attempt.

Reinforcement of STAT3 activity reprogrammes human embryonic stem cells to naive-like pluripotency.

Leukemia inhibitory factor (LIF)/STAT3 signalling is a hallmark of naive pluripotency in rodent pluripotent stem cells (PSCs), whereas fibroblast growth factor (FGF)-2 and activin/nodal signalling is required to sustain self-renewal of human PSCs in a condition referred to as the primed state. It is unknown why LIF/STAT3 signalling alone fails to sustain pluripotency in human PSCs. Here we show that the forced expression of the hormone-dependent STAT3-ER (ER, ligand-binding domain of the human oestrogen receptor) in combination with 2i/LIF and tamoxifen allows human PSCs to escape from the primed state and enter a state characterized by the activation of STAT3 target genes and long-term self-renewal in FGF2- and feeder-free conditions. These cells acquire growth properties, a gene expression profile and an epigenetic landscape closer to those described in mouse naive PSCs. Together, these results show that temporarily increasing STAT3 activity is sufficient to reprogramme human PSCs to naive-like pluripotent cells.

Subcellular dynamics of the maternal cell death regulator BCL2L10 in human preimplantation embryos.

STUDY QUESTION: What is the expression status and subcellular localization of the maternally expressed Bcl-2 family member, BCL2L10, in early human embryos of diverse developmental stages and quality? SUMMARY ANSWER: The anti-apoptotic protein, BCL2L10, is expressed in human preimplantation embryos at least until the blastocyst stage and appears to be differentially distributed at the subcellular level between viable embryos and fragmented or arrested embryos. WHAT IS KNOWN ALREADY: BCL2L10 is an anti-apoptotic member of the BCL-2 family that shows abundant expression in human oocytes and limited sequence conservation to its mouse homologue. STUDY DESIGN, SIZE, DURATION: Embryos donated with informed consent by couples consulting for infertility in the Department of Reproductive Medicine (Hôpital Femme Mère Enfant, Bron, France) were divided into two groups: high quality embryos (n = 18) and poor quality embryos (n = 30). Semen samples (n = 4) were obtained after informed consent from men consulting for couple infertility. Experiments involving human preimplantation embryos were performed between January and December 2009. PARTICIPANTS/MATERIALS, SETTING, METHODS: We examined BCL2L10 expression and subcellular localization in early human embryos by using immunofluorescence and confocal microscopy. The subcellular distribution of BCL2L10 was also studied in ejaculated sperm cells and in isolated mouse skeletal muscle fibres. MAIN RESULTS AND THE ROLE OF CHANCE: The BCL2L10 protein was detectable in healthy human preimplantation embryos at least until the blastocyst stage. In high-quality embryos, BCL2L10 was predominantly cytoplasmic with mitochondrial localization. In contrast, BCL2L10 exhibited extra-mitochondrial localization in abnormal embryos, and was nuclear-cytoplasmic in approximately half (17/30) of the poor-quality embryos. Morphologically fragmented embryos showed coexistence of blastomeres with BCL2L10-positive expression and blastomeres or fragments negative for BCL2L10. LIMITATIONS, REASONS FOR CAUTION: Future studies are needed to evaluate whether embryo quality is related to an exclusive mitochondrial localization of BCL2L10. Mechanisms mediating the nuclear translocation of BCL2L10 in abnormal embryos and functions of this nuclear pool of BCL2L10 are currently unknown. WIDER IMPLICATIONS OF THE FINDINGS: The nuclear localization of BCL2L10 in abnormal embryos suggests a potential role for this protein in pathological conditions resulting in embryo arrest. STUDY FUNDING/COMPETING INTEREST(S): No external funding was obtained for this study. There are no competing interests.

Abnormal methylation of KCNQ1OT1 and differential methylation of H19 imprinting control regions in human ICSI embryos.

Summary To evaluate the integrity of genomic imprinting in embryos that failed to develop normally following intracytoplasmic sperm injection (ICSI), we analysed the methylation profile of H19 and KCNQ1OT1 imprinting control regions, H19DMR and KvDMR1 respectively, in high-grade blastocysts and in embryos that exhibited developmental anomalies. Significant hypomethylation of KvDMR1 was specifically observed in 5/5 atypical blastocysts graded BC, which probably reflected the vulnerability of the imprint in the inner cell mass during the methylation remodelling phase in the early embryo. In addition, KvDMR1 was hypermethylated in 2/5 CC graded atypical blastocysts and in 2/8 embryos that exhibited developmental delay. H19DMR appeared differentially methylated in all groups of embryos. DNA methyltransfersase 1 (DNMT1) expression was similar in most of the tested embryos and could not account for the abnormal methylation patterns of KvDMR1 observed.

Analysis of H19 methylation in control and abnormal human embryos, sperm and oocytes.

ART is suspected to generate increased imprinting errors in the lineage. Following an intra cytoplasmic sperm injection (ICSI) procedure, a certain number of embryos fail to develop normally and imprinting disorders may be associated to the developmental failure. To evaluate this hypothesis, we analysed the methylation profile of H19DMR, a paternally imprinting control region, in high-graded blastocysts, in embryos showing developmental anomalies, in the matching sperm and in oocytes of the concerned couples when they were available. Significant hypomethylation of the paternal allele was observed in half of the embryos, independently of the stage at which they were arrested (morula, compacted morula, pre blastocyst or BC-graded blastocysts). Conversely, some embryos showed significant methylation on the maternal allele, whereas few others showed both hypomethylation of the paternal allele and abnormal methylation of the maternal allele. The matching sperm at the origin of the embryos exhibited normal methylated H19 patterns. Thus, hypomethylation of the paternal allele in the embryos does not seem inherited from the sperm but likely reflects instability of the imprint during the demethylating process, which occurred in the early embryo. Analysis of a few oocytes suggests that the defect in erasure of the paternal imprint in the maternal germ line may be responsible for the residual methylation of the maternal allele in some embryos. None of these imprinting alterations could be related to a particular stage of developmental arrest; compared with high-grade blastocysts, embryos with developmental failure are more likely to have abnormal imprinting at H19 (P<0.05).

Oocytes and early embryos selectively express the survival factor BCL2L10.

Apoptosis has been reported in oocytes and human preimplantation embryos both in vitro and in vivo. BCL-2 family proteins are likely to play a pivotal role in controlling oocyte and early embryo degeneration. However, no BCL-2-related survival factors have been identified that would specifically function during oocyte maturation, after fertilization and during early embryogenesis. Here, we performed a comprehensive tissue expression pattern analysis of the BCL-2 family at the mRNA level. While expression of various members was detected in human oocytes and during early primate embryogenesis, our data indicate that BCL2L10 is the predominant maternally loaded Bcl-2 family transcript, revealing an evolutionary conserved expression profile at the egg-to-zygote transition. We provide evidence that BCL2L10 is associated with the microtubule binding protein translationally controlled tumor protein and mitochondria, with a stage-specific redistribution along the pericortical regulatory ooplasm. In dying oocytes, BCL2L10 colocalized with proapoptotic BAX and neutralization of BCL2L10 accelerated oocyte death. We propose BCL2L10 as a novel and prime candidate related to oocyte maturation, fertility, and embryo developmental competence.

Environmental, occupational and familial risks for testicular cancer: a hospital-based case-control study.

Testicular cancer (TC) risk factors remain largely unknown, except for personal history of cryptorchidism and familial history of TC. We conducted a hospital-based case-control study on familial, environmental and occupational conditions in which we compared 229 cases and 800 controls. TC was correlated with cryptorchidism (OR = 3.02; CI: 1.90-4.79), a history of cryptorchidism in relatives (OR = 2.85; CI: 1.70-4.79), and TC (OR = 9.58; CI: 4.01-22.88], prostate cancer (OR = 1.80; CI: 1.08-3.02) and breast cancer (OR = 1.77; CI: 1.20-2.60) in relatives. Living in a rural area or having regular gardening activity (growing fruit or vegetables) was associated with an increased risk of TC (OR = 1.63; CI: 1.16-2.29; OR = 1.84; CI: 1.23-2.75). Regarding occupation, we found a relationship with employment in metal trimming (OR = 1.96; CI: 1.00-3.86), chemical manufacture (OR = 1.88; CI: 1.14-3.10), industrial production of glue (OR = 2.21; CI: 1.15-4.25), and welding (OR = 2.84; CI: 1.51-5.35). In a multivariate model, only a history of cryptorchidism in the men, cryptorchidism in relatives, TC, and breast cancer remained significant. Our findings contribute further evidence to a pattern of TC risk factors, which include the significant weight of personal reproductive history and also of testicular and breast cancer in relatives. By including in a multivariate model variables linked to environmental and occupational exposure and related to familial cancer history, neither living in a rural area nor any occupational exposure appeared to be a potential environmental TC risk factor.

Follicular growth in vitro: detection of growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) during in vitro culture of ovine cortical slices.

Primordial follicles from different mammal species can survive and enter the growth phase in vitro but do not develop beyond the primary stage. The hypothesis was that, in sheep, in vitro follicular growth is arrested because of a lack of secretion of GDF9 and/or BMP15. Cortical slices of 0.3-0.5 mm thickness issued from 5- to 6-month-old lambs were cultured for 15 days. The pieces were fixed on days 0, 2, 4, 7, 10, and 15 of culture. Follicle morphology, RT-PCR exploration of GDF9 and BMP15 mRNA, immunohistochemical location of their proteins and their receptor BMPRIB and BMPRII were assessed at different time of culture. The mean percentage of primordial follicles decreased from 58.6% (day 0) to 13.4% (day 15) (P<0.01), whereas that of primary follicles increased from 3.2% (day 0) to 31.5% on day 4 (P<0.01), then remained stable until day 15 (35.6%). The percentage of atretic follicles increased from 14.7% (day 0) to 27.1% (day 15) (P<0.05). A few secondary follicles were observed on days 4 and 10, representing 1.0%, and 2.1% of the total number of follicles. GDF9 and BMP15 mRNAs were detected from harvesting (day 0) up to day 15 following culture. At the same time, positive immunoreactions for GDF9, BMP15 and for BMPRIB and BMPRII were also found in oocyte cytoplasm. In conclusion, expression of GDF9, BMP15 and their receptors BMPRIB and BMPRII are detected during in vitro culture of ovine cortical slices.

Follicular viability and histological assessment after cryopreservation of whole sheep ovaries with vascular pedicle by vitrification.

OBJECTIVE: To evaluate a cryopreservation technique by vitrification of whole ovaries with their vascular pedicle in sheep, by using two cryoprotectant solutions. DESIGN: Animal study. SETTING: Fertility clinic in a university teaching hospital. ANIMAL(S): Five to 6-month-old ewes. INTERVENTION(S): Whole sheep ovaries with their vascular pedicles were collected at the slaughterhouse and prepared for cryoprotectant toxicity tests and freezing procedures. MAIN OUTCOME MEASURE(S): Follicle viability assessment by trypan blue test and histological examination of ovary and vessel structure. RESULT(S): No statistically significant difference in follicle viability or normal primordial follicle rates were observed between ovaries exposed or nonexposed to cryoprotectant solutions. Nor was any statistically significant difference observed before and after vitrification with the two cryoprotectant solutions. The decrease in the number of primordial follicles was smaller when frozen-thawed ovaries were treated with VS4 solution containing dimethyl sulfoxide, formamide, and propylene glycol. There were fewer nuclear anomalies and general follicular anomalies with the VS4 solution. Pedicle fractures occurred in most ovaries during thawing (11/15). CONCLUSION(S): Cryopreservation of whole ovary by vitrification appears a promising technique in reproductive medicine. The best histologic results were obtained with the VS4 cryoprotectant. Further studies are required to overcome vitrified ovarian vessel fracture.

Upregulation of the BRCA1 gene in human germ cells and in preimplantation embryos.

The quantification of BRCA1 messenger RNA molecules by a quantitative competitive one-step reverse transcriptase polymerase chain reaction method indicates that BRCA1 is upregulated both in human male and female germ cells and in preimplantation embryos. Because BRCA1 is involved in several pathways that participate in preserving intact chromosome and genome integrity, these data suggest that BRCA1 dysfunction might alter human embryogenesis or fertility.

Normal gestations and live births after orthotopic autograft of vitrified-warmed hemi-ovaries into ewes.

BACKGROUND: The aim of this study was to evaluate the long-term outcome of autotransplantation of vitrified warmed hemi-ovaries into ewes. METHODS: Six hemi-ovaries from six ewes aged 6 to 12 months were vitrified. After dissection of the medulla, the hemi-ovarian cortex was stored at -196 degrees C in liquid nitrogen. Four to six weeks after the first laparotomy, the left ovary was removed and the vitrified-warmed hemi-ovary was sutured. RESULTS: Plasma progesterone concentration increased in a regular manner in all ewes. Three pregnancies occurred, from which four lambs were born. The first delivery of a normal lamb occurred in February 2003. The second delivery of two normal lambs occurred in March 2003 (a 2.5 kg male and a 2.8 kg female). The last lamb had a normal delivery but had a malformation of the left leg and the oesophagus. This lamb died two months after delivery from pneumariae. Histological examination of the grafted vitrified ovaries showed few primordial and antral follicles. CONCLUSIONS: These three pregnancies in a ewe model may indicate that ovarian vitrification gives results as good as those from a slow cooling protocol in autograft. It is impossible to establish a link between the vitrification procedure and the malformation of the last lamb, and further studies are needed to evaluate the feasibility of ovarian vitrification.

Quantitation by image analysis of global DNA methylation in human spermatozoa and its prognostic value in in vitro fertilization: a preliminary study.

OBJECTIVE: To determine the relationship between sperm DNA methylation level and sperm characteristics and pregnancy rates. DESIGN: Prospective study. Quantitation by image analysis of DNA methylation in sperm nucleus. SETTING: Department of Reproduction Biology, Edouard Herriot Hospital, Lyon, France. PATIENT(S): Infertile couples undergoing IVF-ET. INTERVENTION(S): The immunostaining of 5 methyl-cytosine was performed on the spare sperm suspension that was used for an assisted reproduction technology procedure. MAIN OUTCOME MEASURE(S): Sperm characteristics according to World Health Organization criteria, sperm motility parameters with computer-assisted semen analysis, sperm DNA methylation level, and heterogeneity index (HI). RESULT(S): Sperm DNA methylation level and HI are correlated with sperm DNA characteristics. HI is negatively correlated with fertilization rate; sperm DNA methylation level is correlated with pregnancy rate. CONCLUSION(S): The DNA methylation level in human spermatozoa could be a new approach to evaluating the ability of spermatozoa to fertilize and lead to normal embryo development.

The cryopreservation of ovarian tissue: uses and indications in veterinary medicine.

Animal experiments have shown that cryopreservation of the ovarian cortex, containing primordial follicles, could be used to preserve gametes thereby restoring fertility in humans and animals. During the last 100 years, many hundreds of species have been lost, and a third of the breeding animals are threatened with extinction. To preserve genetic diversity, notably for the conservation of endangered species, it is essential to conserve female and male gametes. Today, biotechnologies such as artificial insemination and embryo transfer are used in breeding programs and are well developed. However, even using these advanced techniques, there are problems due to the limited number of individuals used as the source of gametes, so that the risk of inbreeding is high, even in large populations. To preserve genetic diversity, it is necessary to create gene banks of male and female gametes and embryos, using a very large number of individual donors. Cryopreservation of ovarian tissue could present a means for enlarging the gene pool. Cryopreserved ovarian tissue could be used in auto- or xenografts, or for in vitro maturation (IVM) of primordial follicles. In this review, we describe the processes for cryopreservation of ovarian tissue and the various possibilities for using it.

Sperm DNA fragmentation decreases the pregnancy rate in an assisted reproductive technique.

BACKGROUND: Standard sperm characteristics are poor predictors of the outcome of IVF treatments. On the contrary, sperm genome quality has been emphasized for several years as playing a major role in early embryogenesis, thus in the success of IVF attempt. METHODS: Sperm DNA fragmentation from a selected group of 104 couples undergoing assisted reproductive techniques (ART) (IVF: n = 50; and ICSI: n = 54) was measured by TUNEL assay and correlated with semen and ART outcomes. RESULTS: A negative correlation was found between sperm characteristics and the proportion of sperm showing DNA fragmentation. For fragmentation >10%, a significant decrease of the fertilization rate was observed. No correlation was found between sperm DNA fragmentation and embryo quality. A high proportion of sperm with fragmented DNA was a pejorative factor to obtain pregnancies when ICSI was performed, but there was no relationship when conventional IVF was performed. CONCLUSIONS: The proportion of sperm with DNA fragmentation appears to be potentially useful as a predictor of ICSI outcome, whereas embryo quality based on morphological criteria, appeared unaffected by DNA fragmentation.

[Treatment of excretory azoospermia. Biological aspects of surgery]. / Le traitement de l'azoospermie excrétoire. La chirurgie face à la biologie.

The therapeutical strategy for excretory azoospermia is very efficient at the present time. It is represented by two complementary methods very different both in their concept and their practical aspects. The surgery for recanalisation of the seminal tract is the old method, associated with reproducible and validated results providing a sophisticated operative methodology which implies microsurgery. The recent introduction of the assisted reproduction technics with better or at least equal results than those of surgery and with a growing therapeutical power already nowadays offers satisfying opportunities of treatment in some selected indications. The evolution of the therapeutical strategy is analyzed through our proper practice and the data of the literature.

Detection and characterization of hepatitis C virus RNA in seminal plasma and spermatozoon fractions of semen from patients attempting medically assisted conception.

To investigate the risk of transmission of hepatitis C virus (HCV) via semen in assisted reproduction techniques, semen samples from 32 men chronically infected with HCV attending a center for assisted procreation were tested for HCV RNA by a reverse transcription-PCR protocol by using a modified version of the Cobas AMPLICOR HCV assay (version 2.0; Roche Diagnostics). The sensitivity of the test was 40 copies/ml. Four of 32 seminal plasma samples (12.5%) were found to be positive for the presence of HCV RNA. The median HCV load in blood was significantly higher in patients who were found to be positive for the presence of HCV RNA in semen than in those who tested negative (P = 0.02). In one man, seven consecutive seminal plasma samples tested positive for HCV RNA, as did two consecutive motile spermatozoon fractions; the corresponding fractions obtained after migration of the spermatozoa remained negative. Despite the absence of the proven infectivity of virus in semen samples that test positive for HCV RNA, these findings highlight the fact that seminal fluid may exhibit prolonged HCV RNA excretion. The usefulness of HCV RNA detection in both seminal plasma and spermatozoon fractions before the start of a program of medically assisted reproduction in couples in whom the male partner is chronically infected with HCV would need to be evaluated prospectively with a larger population of subjects exhibiting HCV RNA in their semen.

Morphological alterations and DNA fragmentation in oocytes from primordial and primary follicles after freezing-thawing of ovarian cortex in sheep.

OBJECTIVE: To evaluate DNA fragmentation in the oocyte of primordial and primary follicles and morphology of these follicles after freezing and thawing of ovarian cortex in sheep using two freezing protocols. DESIGN: Fragmentation of DNA was evaluated by the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) technique. SETTING: Fertility clinic in a large university hospital. ANIMALS: Five- to 6-month-old lambs. INTERVENTION(S): Two-millimeter-thick slices of hemi-ovary cortex were prepared. MAIN OUTCOME MEASURE(S): Histological structure and DNA fragmentation. RESULT(S): In the frozen fragments, the percentage of morphologically normal follicles was significantly lower for both protocols compared with the case of the control group of fresh fragments. There was no significant difference between the two types of freezing protocols (60.4% +/- 13.2% vs. 68.4% +/- 13.7%). However, the distribution of abnormalities (nucleus, cytoplasm, and nucleus and cytoplasm) was dissimilar. The results of the TUNEL technique for the three groups showed no significant difference, but the percentage of the TUNEL-positive follicles was slightly lower for the frozen fragments for both protocols with respect to the control group. CONCLUSION(S): The freezing and thawing process of the ovarian cortex does not induce fragmentation of the DNA on the oocyte of primary and primordial follicles.

Normal pregnancies and live births after autograft of frozen-thawed hemi-ovaries into ewes.

OBJECTIVE: To evaluate long-term outcome of autotransplantation of cryopreserved hemi-ovaries into ewes. DESIGN: Animal study. SETTING: University fertility center, Hospices Civils de Lyon; and Ecole Nationale Vétérinaire de Lyon. PATIENT(S): Grivette ewes. INTERVENTION(S): Six hemi-ovaries from 6 ewes aged 6 to 12 months were frozen with a slow cooling protocol using 2 M of dimethyl sulfoxide as cryoprotectant. After dissection of the medulla, the hemi-ovarian cortex was stored at -196 degrees C in liquid nitrogen. Freezing procedure was performed with a programmable freezer. Semiautomatic seeding was performed before crystallization. Four to 6 weeks after the first laparotomy, the left ovary was removed and the frozen-thawed hemi-ovary was sutured. MAIN OUTCOME MEASURE(S): Mean plasma concentrations of FSH, LH, and progesterone after autotransplantation of frozen-thawed hemi-ovary. Ultrasonography was done to confirm pregnancy. Blood samples were collected weekly to measure FSH, LH, and progesterone. After the first birth, the autografted ovary was removed for histologic examination. RESULT(S): Plasma progesterone concentration increased in a regular manner in all ewes except one 4 weeks after the graft. Concentrations of FSH and LH did not reach the menopausal level. Four pregnancies occurred, from which 6 lambs were born. The first delivery of a normal lamb occurred after 135 days of gestation; the lamb died immediately after birth. The second delivery of two normal lambs occurred after 130 days of gestation. A caesarean section was performed on the third pregnant ewe the 110th days of gestation because the ewe had a vaginal prolapsus. The two normal lambs and the ewe died after surgery. The fourth birth of a normal lamb occurred after 132 days of gestation. Histologic examination of the grafted frozen-thawed ovary showed a regressing corpus luteum and few primordial and antral follicles. CONCLUSION(S): These four pregnancies in a ewe model may indicate that women who undergo preservation of their ovaries before chemotherapy or radiotherapy can have successful pregnancy.