Radiosensitivity of mammalian oocytes with particular reference to the human female

Somatic cell conversion to a germ cell lineage: A violation or a revelation?

The germline is unique and immortal (or at least its genome is). It is able to perform unique jobs (meiosis) and is selected for genetic changes. Part of being this special also means that entry into the germline club is restricted and cells of the soma are always left out. However, the recent evidence from multiple animals now suggests that somatic cells may join the club and become germline cells in an animal when the original germline is removed. This "violation" may have garnered acceptance by the observation that iPScells, originating experimentally from somatic cells of an adult, can form reproductively successful eggs and sperm, all in vitro. Each of the genes and their functions used to induce pluripotentiality are found normally in the cell and the in vitro conditions to direct germline commitment replicate conditions in vivo. Here, we discuss evidence from three different animals: an ascidian, a segmented worm, and a sea urchin; and that the cells of a somatic cell lineage can convert into the germline in vivo. We discuss the consequences of such transitions and provide thoughts as how this process may have equal precision to the original germline formation of an embryo.

Reproductive Effects of Exposure to Low-Dose Ionizing Radiation: A Long-Term Follow-Up of Immigrant Women Exposed to the Chernobyl Accident

The Chernobyl accident in 1986 spread ionizing radiation over extensive areas of Belarus and Ukraine, leading to adverse health effects in exposed children. More than 30 years later, exposed children have grown and became parents themselves. This retrospective study from Israel was aimed to evaluate whether Chernobyl-exposed women are at higher risk for adverse reproductive outcomes. Exposed immigrants were identified as high or low exposure based on Caesium-137 soil contamination levels registered in the town they lived in. The exposed group was age matched with three comparison groups: non-exposed immigrant women from the Former Soviet Union (FSU) excluding Belarus and the Ukraine, immigrants from other countries (Non FSU) and Israeli-born women at a ratio of 1:10. Chernobyl-exposed women were more likely to be nulliparous and have fewer children (2.1 + 0.8 vs. 3.1 + 1.8, p < 0.001), were more likely to undergo fertility treatments (8.8% vs. 5.8%, adjusted OR = 1.8, 95%CI 1.04-3.2, p = 0.036), and were also more likely to have anemia after delivery (49.4% vs. 36.6%, OR = 1.7, 95%CI 1.2-2.3, p = 0.001), compared to women in the combined comparison groups. The overall fertility of Chernobyl-exposed women seems to be reduced as reflected by the lower number of children and their greater need for fertility treatments.

Geography of follicle formation in the embryonic mouse ovary impacts activation pattern during the first wave of folliculogenesis

During embryonic development, mouse female germ cells enter meiosis in an anterior-to-posterior wave believed to be driven by retinoic acid. It has been proposed that ovarian follicle formation and activation follow the same general wave of meiotic progression; however, the precise anatomic specification of these processes has not been delineated. Here, we created a mouse line using Mvh, Gdf9, and Zp3 promoters to drive distinct temporal expression of three fluorescent proteins in the oocytes and to identify where the first follicle cohort develops. The fluorescent profile revealed that the first growing follicles consistently appeared in a specific region of the ovary, the anterior-dorsal region, which led us to analyze if meiotic onset occurred earlier in the dorsal ovarian region. Surprisingly, in addition to the anterior-to-posterior wave, we observed an early meiotic entry in the ventral region of the ovary. This additional anatomic stratification of meiosis contrasts with the localization of the initial follicle formation and activation in the dorsal region of the ovary. Therefore, our study suggests that the specification of cortical and medullar areas in the ventral and dorsal regions on the ovary, rather than the onset of meiosis, impacts where the first follicle activation event occurs.

Successful delivery after abdominal radical trachelectomy followed by adjuvant chemotherapy for advanced invasive uterine cervical cancer: a case report and literature review

Uterine cervical cancer is increasingly prevalent among young Japanese women who are eager to preserve their fertility, and abdominal radical trachelectomy (ART) is often performed in patients with early-stage invasive lesions. Herein we present details of a 27-year-old woman with stage IB1 cervical cancer. Although the patient received ART, histopathological findings revealed a parametrial invasion. Hence, 3 courses of adjuvant chemotherapy with paclitaxel and carboplatin (TC) were administered, and the patient conceived spontaneously 44 months later. Rupture of the membrane occurred at 32 weeks and 4 days, and a 1822 g female baby was delivered by emergency cesarean section. The patient is alive without disease and her child is growing favorably. This case demonstrates the balance between preservation of fertility and curative adjuvant chemotherapy after ART.

The effects of phthalates on the ovary

Phthalates are commonly used as plasticizers in the manufacturing of flexible polyvinyl chloride products. Large production volumes of phthalates and their widespread use in common consumer, medical, building, and personal care products lead to ubiquitous human exposure via oral ingestion, inhalation, and dermal contact. Recently, several phthalates have been classified as reproductive toxicants and endocrine-disrupting chemicals based on their ability to interfere with normal reproductive function and hormone signaling. Therefore, exposure to phthalates represents a public health concern. Currently, the effects of phthalates on male reproduction are better understood than the effects on female reproduction. This is of concern because women are often exposed to higher levels of phthalates than men through their extensive use of personal care and cosmetic products. In the female, a primary regulator of reproductive and endocrine function is the ovary. Specifically, the ovary is responsible for folliculogenesis, the proper maturation of gametes for fertilization, and steroidogenesis, and the synthesis of necessary sex steroid hormones. Any defect in the regulation of these processes can cause complications for reproductive and non-reproductive health. For instance, phthalate-induced defects in folliculogenesis and steroidogenesis can cause infertility, premature ovarian failure, and non-reproductive disorders. Presently, there is a paucity of knowledge on the effects of phthalates on normal ovarian function; however, recent work has established the ovary as a target of phthalate toxicity. This review summarizes what is currently known about the effects of phthalates on the ovary and the mechanisms by which phthalates exert ovarian toxicity, with a particular focus on the effects on folliculogenesis and steroidogenesis. Further, this review outlines future directions, including the necessity of examining the effects of phthalates at doses that mimic human exposure.

Genome-based, mechanism-driven computational modeling of risks of ionizing radiation: The next frontier in genetic risk estimation?

Research activity in the field of estimation of genetic risks of ionizing radiation to human populations started in the late 1940s and now appears to be passing through a plateau phase. This paper provides a background to the concepts, findings and methods of risk estimation that guided the field through the period of its growth to the beginning of the 21st century. It draws attention to several key facts: (a) thus far, genetic risk estimates have been made indirectly using mutation data collected in mouse radiation studies; (b) important uncertainties and unsolved problems remain, one notable example being that we still do not know the sensitivity of human female germ cells to radiation-induced mutations; and (c) the concept that dominated the field thus far, namely, that radiation exposures to germ cells can result in single gene diseases in the descendants of those exposed has been replaced by the concept that radiation exposure can cause DNA deletions, often involving more than one gene. Genetic risk estimation now encompasses work devoted to studies on DNA deletions induced in human germ cells, their expected frequencies, and phenotypes and associated clinical consequences in the progeny. We argue that the time is ripe to embark on a human genome-based, mechanism-driven, computational modeling of genetic risks of ionizing radiation, and we present a provisional framework for catalyzing research in the field in the 21st century.

Taking control of the female fertile lifespan: a key role for Bcl-2 family proteins

Precisely how the length of the female fertile lifespan is regulated is poorly understood and it is likely to involve complex factors, one of which is follicle number. Indeed, the duration of female fertility appears to be intimately linked to the number of available oocytes, which are stored in the ovary as primordial follicles. There is mounting evidence implicating the intrinsic apoptosis pathway, which is controlled by members of the B-cell lymphoma-2 (BCL-2) family, as a key regulator of the number of primordial follicles established in the ovary at birth and maintained throughout reproductive life. Consequently, the pro- and anti-apoptotic BCL-2 family proteins are emerging as key determinants of the length of the female fertile lifespan. This review discusses the relationship between the intrinsic apoptosis pathway, follicle number and length of the female fertile lifespan.

Fertility after breast cancer

Breast cancer is the most common tumor in childbearing women. In the last decades, considerable improvement in breast cancer-related death has been achieved with adjuvant therapies (chemotherapy, endocrine and targeted therapies, radiotherapy) but at cost of significant long-term sequels, including infertility. Reproductive issues are of great importance to young women, in particular for those who did not complete their families before breast cancer diagnosis: patients should be adequately informed at the time of diagnosis about the risk of infertility and the available methods for fertility preservation. This review will focus on incidence and impact of infertility secondary to breast cancer treatment, the available options for ovarian function preservation, including embryo and oocyte cryopreservation, ovarian tissue cryopreservation, and ovarian suppression with gonadotropin-releasing hormone agonists. We will also discuss the optimal time of subsequent pregnancy, the potential risks for the mother and the fetus, and the impact of therapies on breastfeeding.

Optimizing cryoprotectant perfusion conditions for intact ovary: a bovine model

PURPOSE

The aim of this study was to detect the effects of different perfusion pressure and different length of perfusion period on whole ovarian cryopreservation

METHODS

Bovine whole ovaries were vitrified-warmed. The ovaries were divided into the experimental groups according to different perfusion pressure and different length of perfusion period. Follicular viability was assessed using the trypan blue test; the percentage of morphologically normal primordial follicles and the 17-β estradiol level in the culture supernatants were measured.

RESULTS

When perfusion pressure was 100 mmHg, and the length of perfusion period was 40 min, the viability of ovarian tissues in bovine whole ovarian cryopreservation were higher than other protocols.

CONCLUSION

Protocol IIb (the perfusion pressure was 100 mmHg, and the length of perfusion period was 40 min) was appropriate for bovine whole ovarian cryopreservation.

In vivo delivery of FTY720 prevents radiation-induced ovarian failure and infertility in adult female nonhuman primates

OBJECTIVE

To determine whether sphingosine-1-phosphate (S1P), or the S1P mimetic FTY720 shields ovaries of adult female rhesus monkeys from damage caused by 15 Gy of targeted radiotherapy, allowing for the retention of long-term fertility, and to evaluate whether S1P protects human ovarian tissue (xenografted into mice) from radiation-induced damage.

DESIGN

Research animal study.

SETTING

Research laboratory and teaching hospital.

PATIENT(S)

Adult female rhesus macaques (8-14 years of age; n = 21) and two women (24 and 27 years of age) undergoing gynecologic surgery for benign reasons, after informed consent and approval.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Ovarian histologic analysis, ovarian reserve measurements, and fertility in mating trials.

RESULT(S)

Rapid ovarian failure was induced in female macaques by ovarian application of 15 Gy of radiation. Females given S1P or FTY720 by direct intraovarian cannulation for 1 week before ovarian irradiation rapidly resumed menstrual cycles because of maintenance of follicles, with greater beneficial effects achieved using FTY720. Monkeys given the S1P mimetic before ovarian irradiation also became pregnant in mating trials. Offspring conceived and delivered by radioprotected females developed normally and showed no evidence of genomic instability, as measured by micronucleus frequency in reticulocytes. Adult human ovarian cortical tissue xenografted into mice also exhibited a reduction in radiation-induced primordial oocyte depletion when preexposed to S1P.

CONCLUSION(S)

S1P and its analogs hold clinical promise as therapeutic agents to preserve ovarian function and fertility in female cancer patients exposed to cytotoxic treatments.

Effects of cooling rates and ice-seeding temperatures on the cryopreservation of whole ovaries

PURPOSE

The aim of this study was to detect the effects of different cooling rates and different ice-seeding temperatures on the cryopreservation of whole ovaries.

METHODS

Cow whole ovaries were slowly frozen using different protocols with different cooling rates and different ice-seeding temperatures. Follicular viability was assessed using the trypan blue test; the percentage of morphologically normal primordial follicles and the follicular densities of grafts were measured.

RESULTS

Protocol IIb was most effective protocol. Protocol Ib was more effective than protocol Ia and protocol Ic, and protocol IIIb was more effective than protocol IIIa and protocol IIIc.

CONCLUSIONS

Protocol IIb (the cooling rate was 0.2°C/min, and the ice-seeding temperature was -5°C) was appropriate for slow freezing of cow whole ovaries.

Cryopreservation of whole ovaries with vascular pedicles: vitrification or conventional freezing?

PURPOSE

To compare the efficacy of vitrification and conventional freezing of whole ovaries.

METHODS

Ovaries obtained from 5-year-old female bovines were cryopreserved by conventional freezing, rapid freezing and vitrification. The ovarian cortical strips were cryopreserved by conventional freezing. Follicular viability was assessed using the trypan blue test; the percentage of morphologically normal primordial follicles, hormones concentrations in the culture supernatants, and lactate dehyrogenase levels were measured.

RESULTS

The efficacy of cryopreservation of whole ovaries by vitrification was higher than those by conventional freezing and rapid freezing. Conventional freezing of ovarian cortical strips was more effective than cryopreservation of whole ovaries by conventional freezing, rapid freezing, and vitrification.

CONCLUSIONS

Vitrification seems to be more suitable than conventional freezing for cryopreservation of whole ovaries. However, further studies are required to improve the efficacy of vitrifying whole ovaries.

Is caspase inhibition a valid therapeutic strategy in cryopreservation of ovarian tissue?

PURPOSE

The aim of this study is to determine whether inclusion of caspase inhibitor can improve the efficacy of cryopreservation of ovarian tissue.

METHODS

Mice were randomly assigned to the Group A (fresh control group) Group B (inclusion of caspase inhibitor) and Group C (non-inclusion of caspase inhibitor). Ovarian tissue in Group B and Group C was vitrified-thawed. TUNEL assay and Bax protein detection were measured after cryopreservation. The mice in all groups received autotransplantation. The number of days before the resumption of estrous cycles was measured daily from the 5th day after surgery, and the percentage of cells expressing PCNA in grafts was measured one month following transplantation.

RESULTS

The incidence of TUNEL positive follicles in Group B was significantly higher than that in Group C. Similarly, the percentage of follicles expressing Bax protein in Group B was significantly higher than that in Group C. The number of days before the resumption of estrous cycles in Group B was significantly less than that in Group C. In addition, the percentage of follicular and stromal cells expressing PCNA of grafts in Group B was significantly higher than that in Group C.

CONCLUSIONS

The global caspase inhibitor Z-VAD-FMK decreases the incidence of apoptosis of ovarian tissue induced by cryopreservation, and inclusion of caspase inhibitor improves the efficacy of cryopreservation of ovarian tissue.

Estrogen-progestin therapy in women after stem cell transplant: our experience and literature review

Women undergoing stem cell transplantation (SCT) are mostly young and have more than 90% probability of ovarian failure, which is often permanent. A woman's age, use of radiotherapy and alkylating chemotherapy, and the allogeneic type of transplant are associated with a higher rate of premature ovarian failure and worse residual ovarian function. Premature ovarian failure has serious systemic and psychological effects that may need treatment and should be managed by practitioners trained to treat this particular population of women. Ultrasonographic evidence of ovarian follicles is often associated with a future resumption of cycles, but there are no serum markers to predict the return of ovarian function in these patients. In our center, the rate of ovarian function recovery was 7% after allogeneic SCT and 25% after autologous SCT (P<0.05). There are no guidelines on how to manage premature ovarian failure induced by myeloablative treatments followed by SCT. Because of the likelihood of the need for long-lasting estrogen plus progestin therapy (EPT) and the increased risk of secondary neoplasia after SCT, the EPT should be as physiological as possible. In our experience, the cyclical sequential combination of estradiol (2 mg daily) plus dydrogesterone (10 mg for 14 d/mo) was associated with excellent compliance because of its simple administration and few adverse effects. Such a treatment led to a dramatic improvement in vasomotor, urogenital, and psychological symptoms related to estrogen deficiency. However, in the allogeneic transplantation setting, up to 25% of women may suffer from gynecological chronic graft-versus-host disease, which may become apparent as hematocolpometra after introduction of EPT. Thus, accurate pretreatment evaluation and frequent monitoring during treatment are required. Moreover, EPT absorption may be reduced in patients who received allotransplants and have gastrointestinal or skin chronic graft-versus-host disease.

Depletion of ovarian follicles with age in chimpanzees: similarities to humans

We retrieved ovarian sections taken from necropsies of 19 captive chimpanzees (Pan troglodytes) aged 0-47 yr, counted the number of primordial follicles in each, and compared the rate of decline in numbers to declines previously documented in humans. The follicular depletion rate in this sample was indistinguishable from that shown across the same ages in classic human data sets. This result supports earlier suggestions that ovarian senescence occurs at the same ages in chimpanzees and humans, implying that the influence of declining ovarian function on other physiologic systems may be distinctively buffered in humans.

Reproductive ageing in women

The traditional view in respect to female reproduction is that the number of oocytes at birth is fixed and continuously declines towards the point when no more oocytes are available after menopause. In this review we briefly discuss the embryonic development of female germ cells and ovarian follicles. The ontogeny of the hypothalamic-pituitary-gonadal axis is then discussed, with a focus on pubertal transition and normal ovulatory menstrual cycles during female adult life. Biochemical markers of menopausal transition are briefly examined. We also examine the effects of age on female fertility, the contribution of chromosomal abnormalities of the oocyte to the observed decline in female fertility with age and the possible biological basis for the occurrence of such abnormalities. Finally, we consider the effects of maternal age on obstetric complications and perinatal outcome. New data that have the potential to revolutionize our understanding of mammalian oogenesis and follicular formation, and of the female reproductive ageing process, are also briefly considered.

Successful pregnancies after transplantation of frozen–thawed mouse ovaries into chimeric mice that received lethal-dose radiation

OBJECTIVE

To study whether fecundity was recovered in mice into which umbilical cord blood cells (UCBCs) were transfused after lethal-dose radiation, followed by transplantation of frozen-thawed ovaries.

DESIGN

Prospective basic research study.

SETTING

Academic research laboratory.

ANIMAL(S)

Female C57BL/6 mice as recipients of UCBCs and ovaries, male B6C3F1 mice for mating, and green fluorescent protein (GFP)-transgenic mice: 18.5-day-old fetuses (-/+) for UCBCs and adult GFP mice (+/+) for ovarian tissues.

INTERVENTION(S)

The UCBCs were transfused into each irradiated mouse, with GFP+ ovaries transplanted 4 weeks later. The chimeric mice were mated 3 weeks after ovarian transplantation and were examined 14 to 16 weeks after the transfusion of UCBCs.

MAIN OUTCOME MEASURE(S)

Percentage of chimerism, number of GFP+ pups.

RESULT(S)

The percentage of chimerism in these mice tends to increase with the radiation dose. The recovery of fecundity was observed in the chimeric mice that were transplanted with fresh and previously vitrified ovaries after exposure to radiation.

CONCLUSION(S)

Even when the exposure dose of radiation administered as pretreatment is lethal, the fecundity of recipients can be maintained if their ovaries are cryopreserved before they are exposed to radiation.

Chromosomal aberrations induced by (12)C6+ ions and 60Co gamma-rays in mouse immature oocytes

The ovaries of Kun-Ming strain mice (3 weeks) were irradiated with different doses of (12)C6+ ion or (60)Co gamma-ray. Chromosomal aberrations were analyzed in metaphase II oocytes at 7 weeks after irradiation. The relative biological effectiveness (RBE) of (12)C6+ ion was calculated with respect to 60Co gamma-ray for the induction of chromosomal aberrations. The (12)C6+ ion and 60Co gamma-ray dose-response relationships for chromosomal aberrations were plotted by linear quadratic models. The data showed that there was a dose-related increase in frequency of chromosomal aberrations in all the treated groups compared to controls. The RBE values for (12)C6+ ions relative to 60Co gamma-rays were 2.49, 2.29, 1.57, 1.42 or 1.32 for the doses of 0.5, 1.0, 2.0, 4.0 or 6.0 Gy, respectively. Moreover, a different distribution of the various types of aberrations has been found for (12)C6+ ion and 60Co gamma-ray irradiations. The dose-response relationships for (12)C6+ ion and 60Co gamma-ray exhibited positive correlations. The results from the present study may be helpful for assessing genetic damage following exposure of immature oocytes to ionizing radiation.

Quantitative assessment of ischemic tissue damage in ovarian cortical tissue with or without antioxidant (ascorbic acid) treatment

OBJECTIVE

To estimate ischemic tissue damage in ovarian cortex and to evaluate the effectiveness of ascorbic acid, an antioxidant, to protect ovarian tissue from apoptosis caused by ischemia.

DESIGN

In vitro laboratory experiments.

SETTING

Academic research institute.

INTERVENTION(S)

Fresh and frozen/thawed cortical sections of bovine ovaries were incubated in MEM medium with or without ascorbic acid for a duration of 3, 24, and 48 hours at 37 degrees C.

MAIN OUTCOME MEASURE(S)

Oxygen consumption rates, lactate dehydrogenase concentrations, apoptosis rates determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining, and DNA fragmentation analysis.

RESULT(S)

The oxygen consumption rates were correlated inversely with the duration of incubation. When the rates of apoptosis in primordial follicles with or without ascorbic acid treatment were compared, there was no statistically significant difference between the two groups. However, the ascorbic acid treatment group showed significantly decreased apoptosis in ovarian cortex (stromal cells) with 24 hours of incubation.

CONCLUSION(S)

The correlation between ischemic tissue damage and the duration of ischemia was verified. Ovarian cortex could tolerate ischemia at least for 3 hours. Ascorbic acid treatment reduced apoptosis in ovarian cortex up to 24 hours of incubation in vitro. It appeared that stromal cells were more vulnerable to ischemia compared to primordial follicles.

Evaluation of the hormonal function and histological features of heterotopic isogenic ovarian transplantation in rats

The purpose of the study was to determine the feasibility of preserving ovarian function after heterotopic transplantation by means of microvascular anastomosis of the transplanted vascular pedicles to a set of preselected vessels. Six groups of 10 Sprague-Dawley inbred rats were used in this study. Group I underwent bilateral ovariectomy operation and served as the ovariectomy control. Group II underwent bilateral ovariectomy followed by heterotopic isogenic ovarian implantation. Group III underwent bilateral ovariectomy and isogenic heterotopic ovarian transplantation by means of microvascular anastomosis. Group IV served as the laparotomy sham-operated control. Group V served as the ovarian donor for group II. Group VI served as the donor of the ovarian-kidney vascular pedicle complex for group III. Postoperative ovarian estradiol levels were measured, and histological characteristics were elucidated in groups I, II, III, and IV. The results demonstrated that the estradiol level of the transplantation group was comparable to that of the sham operation group and was significantly higher than that of the implantation group. Histologically normal ovarian architecture was observed in the sham group (IV) and also in the transplantation group (III). Altered architecture was observed in the implantation group (II). These findings indicate that extraabdominal heterotopic ovarian transplantation with microvascular anastomosis led to normal ovarian hormonal function and was effective in preserving oocyte production capacity.

Apoptosis in the human ovary

Programmed cell death or apoptosis is an essential component of human ovarian function and development. During early fetal life approximately 7 x 10(6) oocytes are formed in the human ovary. However, the number of oocytes is dramatically reduced already before birth through apoptotic cell death. In reproductive life, a number of primordial follicles start growing during each menstrual cycle. Usually only one will ovulate and the fate of the rest of the follicles is atresia through the mechanism of apoptosis. Ultimately, only around 400 follicles will ovulate during a woman's reproductive life. After ovulation, the dominant follicle forms the corpus luteum, a novel endocrine gland that is responsible for the production of progesterone and maintenance of endometrium during early pregnancy. If pregnancy does not occur, corpus luteum action must cease so that new follicles can resume growing during the next menstrual cycle. Apoptosis is also responsible for corpus luteum regression in the human ovary. In recent years, new knowledge of the role and regulation of apoptosis in the ovary has been acquired through the use of knockout and transgenic animals. Apoptosis seems to be the mechanism that makes the female biological clock tick. The following review will discuss the role of apoptosis and its regulation of human ovarian function.

Growth following malignancy

Disturbed growth in the child surviving cancer is multifactorial. This chapter examines the evidence for, and the difficulties in determining, individual drug treatment or disease effects at multiple endocrine levels influencing growth and against a changing baseline of adjuvant cancer therapies with potentially additive toxicity. The evolutionary pattern and potential aetiology of the neuro-endocrine deficit and growth-plate disturbance, the (unrandomized) effects of hormone replacement therapy and areas which require further study are also addressed. The reasons why growth hormone (GH) secretion is so exquisitely sensitive to disturbance, even though deficiencies soon after lesser cranial insults can be difficult to detect, are explored with evidence cited from the few existing prospective and interventional studies. The extent and nature of the hypothalamo-pituitary disturbance needs further prospective interventional study and disease-site- and treatment-specific comparisons. Practical treatment and surveillance strategies to optimize growth potential, age-appropriate development, peak bone mineral accretion, hair re-growth and future health and well-being are also suggested. Health-related outcomes resulting from today's newer therapies and enhanced surveillance need documenting in future (inter)national cancer trials, where randomized studies of hormonal intervention may also become possible.

Follicular development, ovulation, and corpus luteum formation in cryopreserved human ovarian tissue after xenotransplantation

OBJECTIVE

To assess the competency of human frozen/thawed ovarian follicles matured in xenografts to form functioning corpora luteae after human chorionic gonadotropin (hCG) administration.

DESIGN

Prospective controlled animal study.

SETTING

University research laboratory.

PATIENT(S)

Three women (19, 28, and 36 years) who underwent oophorectomy.

ANIMAL(S)

Nineteen female severe combined immunodeficient (SCID) mice.

INTERVENTION(S)

Cryopreserved human ovarian tissues were grafted into the s.c. space of bilaterally oophorectomized SCID mice. All the animals were stimulated with pregnant mare's serum gonadotropin (PMSG) for 4 weeks starting from 16 weeks after transplantation. Twelve animals were injected with hCG at the end of gonadotropin stimulation.

MAIN OUTCOME MEASURE(S)

[1] The rate of grafts with growing follicles, with antral follicles, and/or with corpora luteae. [2] The histologic assessment of follicles and corpora luteae. [3] The serum progesterone and estradiol level in animals with corpus luteum in the grafts.

RESULT(S)

[1] The rate of grafts with growing follicles and with corpora luteae was 33% to 100%, and 28% to 50%, respectively. [2] Corpora luteae in xenografts were all morphologically normal. [3] The progesterone levels were all above 3.0 ng/mL.

CONCLUSION(S)

This study showed that the cryopreserved human ovarian follicles can be matured to a stage at which they can form functioning corpora luteae in the host animal.

Radiation damage to the uterus -- review of the effects of treatment of childhood cancer

At the present time approximately 1 in 1000 young people aged between 16 and 35 years will have been cured of cancer in childhood and some of the treatment regimens used will have predictable effects on their future fertility prospects. In young women who have been exposed to radiotherapy below the diaphragm, the reproductive problems include the risk of ovarian failure and significantly impaired development of the uterus. The magnitude of the risk is related to the radiation field, total dose and fractionation schedule. Premature labour and low birth weight infants have been reported after flank abdominal radiotherapy. Female long-term survivors treated with total body irradiation and marrow transplantation are also at risk of ovarian follicular depletion and impaired uterine growth and blood flow, and of early pregnancy loss and premature labour if pregnancy is achieved. Despite standard oestrogen replacement, the uterus of these young girls is often reduced to 40% of normal adult size. Uterine volume correlates with the age at which radiation was received. Regrettably, it is likely that radiation damage to the uterine musculature and vasculature adversely affects prospects for pregnancy in these women. It has been demonstrated that, in women treated with total body irradiation, sex steroid replacement in physiological doses significantly increases uterine volume and endometrial thickness, as well as re-establishing uterine blood flow. However, it is not known whether standard regimens of oestrogen replacement therapy are sufficient to facilitate uterine growth in adolescent women treated with total body irradiation in childhood. Even if the uterus is able to respond to exogenous sex steroid stimulation, and appropriate assisted reproductive technologies are available, a successful pregnancy outcome is by no means ensured. The uterine factor remains a concern and women who are survivors of childhood cancer and their carers must recognize that these pregnancies will be at high risk.

The future of human ovarian cryopreservation and transplantation: fertility and beyond

OBJECTIVE

To review the current progress in ovarian cryopreservation and transplantation and to discuss the obstacles with the clinical application of this technique.

DESIGN

The literature on ovarian cryopreservation and transplantation was reviewed to facilitate understanding and predict future directions. The studies related to this topic were identified through MEDLINE and other bibliographic databases, focusing on the most recent developments.

CONCLUSION(S)

The experimental evidence for low-temperature storage of ovarian tissue is encouraging. Although restoration of fertility with cryopreserved ovarian grafts has been successful in various animals, there are uncertainties about the optimum use of stored ovarian tissue in humans. Autotransplantation appears to be promising, but the potential risk of transmitting malignant cells in women with cancer is of great concern. The maturation of primordial follicles with xenotransplantation is encouraging, but the efficacy and the safety of this method need further investigation. Furthermore, the quality of oocytes that have been matured in a host animal is unknown. The development of in vitro culture systems for oocyte maturation is still in its infancy. There are many issues to be resolved in ovarian transplantation before the full clinical use of this emerging technique. Most of all, there is an urgent need to optimize the freeze/thaw procedure and to find the means to protect grafts from ischemia-reperfusion injury. Nevertheless, ovarian transplantation should prove to be clinically useful for women at risk for premature ovarian failure.

Gonadal cryopreservation in the young patient with gynaecological malignancy

For patients who are planning to have chemotherapy, radiotherapy or to undergo bilateral oophorectomy, the loss of ovarian function will result in premature ovarian menopause and loss of fertility. Embryo preservation is not an option for single women or married women because delaying treatment for at least 2 months of in-vitro fertilization cycles is inappropriate and may be life-threatening. This study reports on the indications for ovarian tissue cryobanking and the state of the art of this method in preserving fertility in women with iatrogenic premature menopause.

Freezing, thawing, and autograft of ovarian fragments in sheep: preliminary experiments and histologic assessment

OBJECTIVE

To evaluate the effects of freezing and thawing on the histologic changes in ovarian fragments from sheep and to determine the feasibility of ovarian autografts.

DESIGN

Histologic evaluation of follicles that survived after freezing at -196 degrees C for 2 weeks. Histologic evaluation of ovarian fragments 6 months after the autografts.

SETTING

Laboratoire de Zootechnie, Ecole National Véterinaire, Marcy l'Etoile, France.

ANIMAL(S)

Six ewes aged 6 months to 1 year.

INTERVENTION(S)

Cortical fragments were prepared from the right ovary of 6 lambs and were grafted immediately to the contralateral ovarian hilus or were cooled slowly to -196 degrees C in medium containing dimethyl sulfoxide for 2 weeks. The autografts were recovered 6 months later.

RESULT(S)

Histologic examination of ovarian slices after freezing showed no destruction of primordial, primary, secondary, or cavitary follicles. The ovarian autograft showed good recovery of the macroscopic and microscopic ovarian structure. After autografting, histologic examination revealed primordial to cavitary follicles.

CONCLUSION(S)

Freezing of ovarian fragments is possible without damaging the follicles. Ovarian autografts showed good recovery of ovarian structure.

Conservation of the follicular population in irradiated rats by the cryopreservation and orthotopic autografting of ovarian tissue

AIM

To preserve the follicular population in rats prior to abdominal irradiation by the orthotopic autografting of ovarian cortical slices (frozen/thawed) in one of two cryoprotective agents (CPAs). The proportion of follicular survival will be quantified at autopsy and a comparison will be made of the two CPAs.

METHOD

Thirty Wistar rats, aged 38-39 days, were unilaterally ovariectomised. The ovaries of twenty animals were slow-cooled in either 1.5 M dimethylsulphoxide (DMSO; group B) or 1.5 M ethylene glycol (EG; group C). The ovaries of the remaining ten animals (group A) were fixed and histologically examined to determine a fresh follicle count. The contralateral ovary was irradiated with a single dose of 2.5 Gy. Frozen tissue (from groups B and C) was thawed rapidly and autografted into the irradiated ovarian bursa. All animals were mated eighteen days after grafting and were sacrificed eighteen days later. At autopsy, the number of embryos was counted and the ovarian weights recorded, before the tissue was prepared histologically for quantification of follicular survival.

RESULTS

There was no significant difference in the pregnancy rate in the three groups and, although there was a higher number of embryos in the irradiated control group A compared with groups B and C, the difference was not significant. The follicle count in groups B and C was significantly higher than in group A. In group A, the percentage of growing follicles was higher than in groups B and C and the fresh ovary.

CONCLUSIONS

Autografting frozen/thawed ovarian tissue preserved a proportion of the follicular population in irradiated rats. There was no significant difference in the numbers of follicles surviving cryopreservation in the two CPAs. Since the irradiated rats were not totally sterilised, we cannot conclude that cryopreserved grafts can restore fertility.

Reproductive sequelae of cancer treatment

Remarkable advances have been made in the treatment of cancers that afflict patients of the reproductive age. Many survivors must now face the effects on gonadal function and have concerns about reproductive capacity. The sequelae of different modalities of cancer therapy specifically addressing surgery, chemotherapy, and radiotherapy on reproductive system are reviewed. Assisted reproductive technologies, prenatal diagnosis methods, and contraception counseling are briefly summarized in conclusion.

The effect of hormone replacement therapy on bone mass in patients with ovarian failure due to bone marrow transplantation

BACKGROUND

Long permanent remissions in malignant hematopoietic disorders can often be achieved by autologous bone marrow transplantation (ABMT) or by allogenic bone marrow transplantation (BMT). Previous studies have shown that such therapies may induce osteoporosis due to iatrogenic ovarian failure. The administration of hormone replacement therapy (HRT) in these women could prevent the adverse effects of long-term ovarian failure without remarkable side effects. The aim of this study was to evaluate how the bone mass is affected by HRT in patients undergoing ABMT or BMT adjusting the results for age, weight, and height.

SUBJECTS AND METHODS

Thirteen women with previous ABMT/BMT were treated with a standard dose (0.625 mg/day) of conjugated equine estrogen (CEE) or with 50 micrograms/day of 17-beta-estradiol in transdermal therapeutic systems (TTS) plus 5 mg/day of medroxyprogesterone acetate sequentially added to the last 12 days of estrogen therapy. Bone mass was measured prior to and 12 months following HRT. Blood samples were collected before therapy and during the 6th and 12th treatment months.

RESULTS

The mean time elapsed between bone transplantation and HRT initiation was 13.0 months (range 3-26 months). Before treatment nine patients were osteopenic and after HRT bone mass increased in all cases. Following ABMT/BMT, hepatic hyperenzymemia was detected in three patients. After 6 and 12 months of treatment no significant changes were observed in hepatic enzymes.

CONCLUSION

Although hepatic hyperenzymemia is commonly considered as a contraindication for HRT, our results suggest that HRT is safe for these patients and that such therapy should be initiated after transplantation in women to prevent adverse effects of long-term ovarian failure.

Synaptonemal complex damage in fetal mouse oocytes induced by ionizing irradiation

Fetal female mice were exposed to ionizing irradiation of 2 Gy in a single dose at days 14, 16, and 17 of gestation. Synaptonemal complexes of primary oocytes were analyzed on day 17. It has been demonstrated that electron beam irradiation of early oocytes on day 14 with 2 Gy is accompanied by a duplication of atretic cells. A significant increase in fragmentations of the synaptonemal complexes over the base level became evident when mice were exposed to irradiation on days 16 and 17 of gestation. Frequencies of multivalent formation and univalents were not increased over the levels in the control group. Reduction of fertility and malsegregation of chromosomes may be a reflection of the consequences of the observed nuclear lesions.

Specific-locus experiments show that female mice exposed near the time of birth to low-LET ionizing radiation exhibit both a low mutational response and a dose-rate effect

Female mice were exposed to 300 R of 73-93 R/min X-radiation either as fetuses at 18.5 d post conception (p.c.) or within 9 h after birth. Combining the similar results from these two groups yielded a specific-locus mutation frequency of 9.4 X 10(-8) mutation/locus/R, which is statistically significantly higher than the historical-control mutation frequency, but much lower than the rate obtained by irradiating mature and maturing oocytes in adults. Other females, exposed at 18.5 days p.c. to 300 R of 0.79 R/min gamma-radiation, yielded a mutation frequency that was statistically significantly lower than the frequency at high dose rates. The low-dose-rate group also had markedly higher fertility. It appears that the dose-rate effect for mutations induced near the time of birth may be more pronounced than that reported for mature and maturing oocytes of adults. A hypothesis sometimes advanced to explain low mutation frequencies recovered from cell populations that experience considerable radiation-induced cell killing is that there is selection against mutant cells. The reason for the relatively low mutational response following acute irradiation in our experiments is unknown; however, the finding of a dose-rate effect in these oocytes in the presence of only minor radiation-induced cell killing (as judged from fertility) makes it seem unlikely that selection was responsible for the low mutational response following acute exposure. Had selection been an important factor, the mutation frequency should have increased when oocyte killing was markedly reduced.

Reproductive hazards of fire fighting. I. Non-chemical hazards

Fire fighters are regularly exposed to chemical and non-chemical agents that have known or suspected adverse effects on reproductive health. Although chemical agents have received some attention, non-chemical hazards such as heat, noise, and physical exertion have only recently been examined for their reproductive effects. There is evidence that heat, noise, and physical exertion may affect various endpoints of reproductive health, including fertility, fetal loss, and growth parameters of the offspring. In particular, hyperthermia, a major fire fighting hazard, has been shown to impair male fertility and may also be teratogenic. Further study of the potential reproductive effects of this and other common non-chemical agents in the fire environment is needed to ensure the reproductive health of male and female fire fighters.

Induction of ovulation and pregnancy following lateral oophoropexy for Hodgkin's disease

Present therapy for Hodgkin's disease which primarily affects young patients may produce long term remissions in more than 50% of cases. Potential injuries to the reproductive system from radiation or chemotherapy are significant considerations in therapeutic planning. Assessment of the effects of infradiaphragmatic radiation on germ cells may avoid ovarian ablation in women of reproductive age. This report addresses ovarian function and fertility following lateral oophoropexy and repositioning for Hodgkin's disease.

Early natural menopause and the duration of postmenopausal life. Findings from a mathematical model of life expectancy

Menopause marks the beginning of a stage of life characterized by an increased susceptibility to diseases such as coronary heart disease and osteoporosis. It was therefore hypothesized that early age at natural menopause would lengthen the duration of the postmenopausal stage of life and thereby result in an earlier age at death. This study investigated the relations between age at natural menopause, duration of postmenopausal life (ie, life expectancy at menopause), and age at death (ie, age at menopause plus life expectancy at menopause). Data were derived from a study of 5,287 naturally postmenopausal Seventh-day Adventists observed during 1976-1982. Life expectancy was estimated by a mathematical model that used mortality ratios from the study and mortality rates from the US general population. For natural menopause before the age of 47 years, each one-year decrease in age at menopause was associated with a 0.53-year increase in postmenopausal life (P = .04) and a 0.47-year decrease in the age at death (P = .04). For natural menopause at the age of 47 years and older, however, each one-year decrease in age at menopause was associated with a 0.99-year increase in postmenopausal life (P = .03) and only a 0.01-year decrease in the age at death (P = .85). Overall, these findings argue against the possibility that the association between age at menopause and age at death in this study was due to the relation of age at menopause to the duration of postmenopausal life.

Ovarian failure following abdominal irradiation in childhood: the radiosensitivity of the human oocyte

Ovarian function has been studied sequentially since 1975 in 19 patients treated in childhood for an intra-abdominal tumour with surgery and whole abdominal radiotherapy (total dose 30 Gy). Eleven patients received chemotherapeutic agents that are not known to cause gonadal dysfunction. All but one patient have developed ovarian failure with persistently elevated gonadotrophin levels (FSH and LH greater than 32 IU/litre) and low serum oestradiol values (less than 40 pmol/litre) before the age of 16 years. The majority (n = 12) did not progress beyond breast stage 1 without sex steroid replacement therapy. As the number of oocytes within the ovary declines exponentially by atresia from approximately 2,000,000 at birth to approximately 2000 at the menopause, we have been able to estimate that the LD50 for the human oocyte does not exceed 4 Gy.

Ovarian failure following abdominal irradiation in childhood: natural history and prognosis

Ovarian function has been reviewed sequentially since 1975 in 53 patients treated in childhood between 1942 and 1985 for an intraabdominal tumour with surgery and external abdominal radiotherapy (XRT). Of 38 patients who received whole abdominal XRT (20-30 Gy), 27 failed to undergo or complete pubertal development (pubertal failure) and a premature menopause (median age 23.5 years) occurred in a further ten. Of 15 patients who received flank XRT (20-30 Gy), ovarian function (median age at last assessment 15.2 years) was normal in all but one in whom pubertal failure occurred. In only one patient, who developed pubertal failure after whole abdominal XRT and required sex steroid replacement therapy (HRT) to achieve normal secondary sexual characteristics, has there been evidence of reversibility of ovarian function with a documented conception at the age of 22.7 years. Five patients who developed pubertal failure required bilateral augmentation mammoplasties despite sex steroid replacement therapy. Four patients have had documented conceptions, all received whole abdominal XRT (20-26.5 Gy) and subsequently developed a premature menopause. There have been no live births, with all miscarriages occurring in the second trimester. The outlook for normal ovarian function following whole abdominal XRT is poor, flank XRT introduced intermittently from 1972, has resulted in less pubertal failure but the possibility of a premature menopause may with time become a reality.

Is early natural menopause a biologic marker of health and aging?

The relation between age at natural menopause and all-cause mortality was investigated in a sample of 5,287 White women, ages 55 to 100 years, naturally-postmenopausal, Seventh-day Adventists who had completed mailed questionnaires in 1976. The age-adjusted odds ratio of death during 1976-82 in women with natural menopause before age 40 was 1.95 (95% confidence interval = 1.24, 3.07), compared to the reference group of women reporting natural menopause at ages 50 to 54. Corresponding odds ratios of death were 1.39 (95% CI = 1.06, 1.81) for natural menopause at ages 40 to 44, and 1.03 (95% CI = 0.84, 1.25) for natural menopause at ages 45 to 49. Among 3,166 White, 55- to 100-year-old, surgically-postmenopausal, Adventist women, there was no relation between age at surgical menopause and mortality. Logistic regression analyses indicated that findings from this study were apparently not due to confounding by smoking, over- or underweight, reproductive history, or replacement estrogen use.

Use of primate folliculogenesis models in understanding human reproductive biology and applicability to toxicology

The nonhuman primate reproductive system provides an excellent model for studying basic physiological processes applicable to humans. This article reviews hormonal observations and experimental manipulations useful in the evaluation of ovarian events in various stages of the reproductive life. As the need arises, primate reproductive toxicological studies may clarify questions relevant to human risk evaluations. Evaluation of reproductive toxicological observations may reveal biological parameters defining premature reproductive failure.

Gonadal effects of cancer therapy in girls

The gonadal histology of 21 prepubertal, intrapubertal, and postpubertal girls who died 1 day to 2 months after cessation of therapy for extragonadal solid tumors was reviewed. In addition to focal or diffuse cortical fibrosis, a reduction in follicle numbers and impaired follicular maturation were observed in cancer patients independent of their pubertal age. These changes appeared to be more severe in malnourished patients and in girls who received multiple agent chemotherapy, with or without irradiation. Both before and after the age of 10 years, most cancer patients had a total number of follicles similar to that of age- and nutrition-matched controls. However, the majority of these girls displayed impaired follicular maturation as demonstrated by reduced numbers of growing and antral follicles compared to controls. Histologic evidence of ovarian damage suggests that the future reproductive performance may be impaired in some female cancer patients treated even before puberty.

Ovarian function in young women in long-term remission after treatment for Hodgkin's disease stage I or II

16 young women in long-term remission after first-line treatment for the early stages of Hodgkin's disease were examined for ovarian function 48 to 125 months after termination of therapy. The patients had received mantle field irradiation, plus either irradiation of infradiaphragmatic lymph nodes or 6 cycles of MOPP. 4 patients showed signs of ovarian failure judged by menopausal symptoms, menstrual pattern and/or hormone values. 12 patients had functioning ovaries; 8 of these had become pregnant after treatment, 2 had had an induced abortion, and 7 had given birth to a total of 9 healthy babies after treatment. The patients with signs of ovarian failure were older than the others, but the difference was not statistically significant. No difference between the patients who had received different treatments was established, nor does the study confirm the proposed protective effect of oral contraceptives. For women under 35 years of age, the long-term chances of preserving ovarian function after standard treatment for the lower stages of Hodgkin's disease seem to be much better than hitherto assumed.