Reproduction & Fertility最新文献

{"title":"Onset of normal cycles in postpartum anovulatory dairy cattle treated with kisspeptin.","authors":"Chris R Burke,&nbsp;John R Roche,&nbsp;Robert P Millar,&nbsp;Iain J Clarke","doi":"10.1530/RAF-21-0046","DOIUrl":"https://doi.org/10.1530/RAF-21-0046","url":null,"abstract":"<p><p>The efficacy of a long-acting synthetic derivative of kisspeptin (Kp) to initiate normal oestrous cycles was tested in 24 mixed-aged, Holstein-Friesian cows that were 18-25 days postpartum on the day of treatment (D0). Groups of eight cows received saline (Sal) vehicle by intramuscular injection at 8:00 and 16:00 h (Sal-Sal), Kp at 8:00 h and vehicle at 16:00 h (Kp-Sal) or Kp on both occasions (Kp-Kp). The Kp dose was 15 nmol per 60 kg body weight. The ovaries of the cows were examined daily by ultrasonography between D4 and D14. Blood samples were collected from a tail vessel at 0, 2, 4, 8, 10 and 12 h relative to the time of the first injection for luteinizing hormone (LH) and follicle-stimulating hormone assay. Additional samples were collected daily from D4 until D14 and D19, 22, 26 and 29 for progesterone assay. LH surge-like responses were observed in cows treated with Kp at 8:00 h. Ovulation was consistently induced by Kp within 48 h when a dominant ovarian follicle of at least 10 mm in diameter was observed (8/14) but in no cases (6/14) during a new wave of ovarian follicular development comprising follicles <10 mm in diameter. The subsequent ovulatory cycle was of normal length in most cases as compared with short 8- to 12-day cycles observed in spontaneously ovulating cows. We conclude that Kp treatment can induce ovulation in postpartum dairy cows, with ensuing oestrous cycles of normal length, if administered when a mature dominant follicle is present in the ovaries.</p><p><strong>Lay summary: </strong>Cow fertility is important for efficient, profitable dairy farming. Cows that take too long after calving to become fertile are problematic. We tested a synthetically made, long-acting hormone called kisspeptin (Kp) to advance the time that cows become fertile after calving. Twenty-four dairy cows that had been calved for 3-4 weeks were used. One group of eight cows received an injection of Kp at the morning milking, another eight cows received Kp at both the morning and afternoon milking, while the last group of eight cows served as untreated controls. Kp treatment caused a desirable hormone response from the cows' brain. Normal oestrous cycles resulted, but only when a mature follicle was present in the ovary. Further study is required to analyse whether the use of a long-acting Kp drug could be used as an effective treatment for stimulating dairy cows to become more fertile after calving.</p>","PeriodicalId":21128,"journal":{"name":"Reproduction & Fertility","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8789012/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39590540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fixation in Form-Acetic allows hyaluronic acid detection in mouse ovaries.","authors":"R Appeltant,&nbsp;B V Adeniran,&nbsp;S A Williams","doi":"10.1530/RAF-21-0085","DOIUrl":"https://doi.org/10.1530/RAF-21-0085","url":null,"abstract":"<p><p>To visualise tissues to determine the presence of disease or simply to understand anatomy, it is important to preserve fresh tissue. Fixatives are chemical solutions that preserve tissues to enable microscopic evaluation. However, some fixatives introduce artefact such as shrinkage of cells. Recently, a new fixative, Form-Acetic, was developed that is superior for preserving the structure of ovary tissue and allows investigation of ovary composition. One component of the ovary is hyaluronic acid (HA), which plays a crucial role in normal ovary function and fertility. Importantly, HA is sensitive to different fixative solutions. Therefore, it is meaningful to verify whether Form-Acetic is suitable for detecting HA. In this study, adult mouse ovaries were fixed in Form-Acetic and HA was detected. All HA-containing structures in the ovary were clearly distinguished which proves that the novel fixative allows the detection of HA.</p>","PeriodicalId":21128,"journal":{"name":"Reproduction & Fertility","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8788581/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39590537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nonhormonal therapy for endometriosis based on energy metabolism regulation.","authors":"Hiroshi Kobayashi,&nbsp;Hiroshi Shigetomi,&nbsp;Shogo Imanaka","doi":"10.1530/RAF-21-0053","DOIUrl":"https://doi.org/10.1530/RAF-21-0053","url":null,"abstract":"<p><p>Ovarian function suppression is the current pharmacotherapy of endometriosis with limited benefit and adverse effects. New therapeutic strategies other than hormonal therapy are developed based on the molecular mechanisms involved in the hypoxic and oxidative stress environments and metabolism unique to endometriosis. A literature search was performed between January 2000 and March 2021 in the PubMed database using a combination of specific terms. Endometriosis-associated metabolic changes have been organized into four hallmarks: (1) glucose uptake, (2) aerobic glycolysis, (3) lactate production and accumulation, and (4) metabolic conversion from mitochondrial oxidative phosphorylation (OXPHOS) to aerobic glycolysis. Endometriotic cells favor glycolytic metabolism over mitochondrial OXPHOS to produce essential energy for cell survival. Hypoxia, a common feature of the endometriosis environment, is a key player in this metabolic conversion, which may lead to glucose transporter overexpression, pyruvate dehydrogenase kinase 1 (PDK1) and lactate dehydrogenase kinase A (LDHA) activation, and pyruvate dehydrogenase complex inactivation. Evading mitochondrial OXPHOS mitigates excessive generation of reactive oxygen species (ROS) that may trigger cell death. Therefore, the coinactivation of LDHA and PDK1 can induce the accumulation of mitochondrial ROS by converting energy metabolism to mitochondrial OXPHOS, causing endometriotic cell death. Metabolic pattern reconstruction in endometriotic lesions is a critical factor in cell survival and disease progression. One therapeutic strategy that may avoid hormone manipulation is focused on mitigating metabolic changes that have been detected in cells/tissues from women with endometriosis.</p><p><strong>Lay summary: </strong>The most commonly used medical therapies for endometriosis have contraceptives and other side effects associated with hormone suppression and are therefore unsuitable for women desiring pregnancy. One therapeutic strategy that may avoid hormone manipulation is focused on changing metabolic profiles that have been detected in cells/tissues from women with endometriosis. Endometriotic cells favor glycolytic metabolism over mitochondrial oxidative phosphorylation (OXPHOS) to produce essential energy for cell growth. Furthermore, the metabolic conversion from mitochondrial OXPHOS to aerobic glycolysis suppresses cell death through the reduced generation of reactive oxygen species (ROS). This unique metabolic feature of endometriosis is important for cell survival and disease progression. Thus, changing the specific metabolic switch may increase mitochondrial ROS production, causing severe oxidative stress and cell death. This review describes new treatments by changing the metabolic profiles of endometriosis.</p>","PeriodicalId":21128,"journal":{"name":"Reproduction & Fertility","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8788578/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39765389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Is there a valid ethical objection to the clinical use of <i>in vitro</i>-derived gametes?","authors":"Kristian Galea","doi":"10.1530/RAF-21-0066","DOIUrl":"10.1530/RAF-21-0066","url":null,"abstract":"","PeriodicalId":21128,"journal":{"name":"Reproduction & Fertility","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8788572/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39590538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Retrospective cohort study on preparation regimens for frozen embryo transfer.","authors":"Monique Atkinson,&nbsp;Jenny Crittenden,&nbsp;Howard Smith,&nbsp;Cecilia Sjoblom","doi":"10.1530/RAF-21-0044","DOIUrl":"https://doi.org/10.1530/RAF-21-0044","url":null,"abstract":"<p><p>The objective of this study was to examine the pregnancy outcomes from frozen embryo transfer (FET) cycles using different endometrial preparation regimens, compared to ovulation induction with letrozole (letrozole OI). A retrospective cohort study was conducted at a fertility centre in Sydney, Australia, on 6060 FET cycles. The cycles were stratified into one of four ways to achieve endometrial preparation. These were either a natural, letrozole OI, OI with follicle-stimulating hormone (FSH OI) or a programmed cycle. The primary outcome was live birth rate (LBR) per embryo transfer. Secondary outcomes included clinical pregnancy and biochemical pregnancy rates, adverse events including miscarriage, ectopic pregnancy, stillbirth, neonatal death and multiple births. Ovarian stimulation parameters were also analysed including the time taken to reach the luteal phase and the number of blood or urine tests required for monitoring the cycle. The results of the study showed that the LBR following letrozole OI cycles was higher when compared to natural cycles (odds ratio (OR): 1.27 (1.07-1.49)) and programmed cycles (OR: 2.36 (1.67-3.34)). There was no significant difference between letrozole OI and FSH OI LBR (OR: 0.99 (0.76-1.28)). An improved LBR with letrozole OI compared to natural cycles was maintained when only women with a normal length cycle were considered (OR: 1.44 (1.10-1.89)). There was a significant reduction in miscarriage rates when letrozole OI was compared to programmed cycles (OR: 0.46 (0.26-0.83)). It was therefore concluded that the use of letrozole OI for endometrial preparation in an FET cycle may be associated with higher LBR and lower miscarriage rate, compared to using a programmed cycle.</p><p><strong>Lay summary: </strong>Couples suffering from infertility frequently try to conceive following the transfer of an embryo which has been frozen during an <i>in vitro</i> fertilisation cycle. Embryos will only lead to a pregnancy if the woman's womb lining has particular characteristics that allow it to accept the embryo. Despite the thousands of frozen embryo transfer cycles carried out across the world, it is not known how best to prepare a woman's lining so it has these particular characteristics. This study looked at the pregnancy outcomes of 6060 cycles to compare four different ways to prepare a woman's womb lining. These included relying on a woman's natural menstrual cycle, or using an oral medication called letrozole, or injectable medicine called follicle-stimulating hormone, or oestrogen and progesterone hormonal medications. The comparison found that using letrozole before transfer of a frozen embryo may be associated with higher rates of a live birth for some women.</p>","PeriodicalId":21128,"journal":{"name":"Reproduction & Fertility","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8788575/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39765386","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Can antioxidants protect against chemotherapy in a rat spermatogonial stem cell line?","authors":"Caroline M Allen,&nbsp;Federica Lopes,&nbsp;Rod T Mitchell,&nbsp;Norah Spears","doi":"10.1530/RAF-21-0042","DOIUrl":"https://doi.org/10.1530/RAF-21-0042","url":null,"abstract":"<p><p>Boys administered chemotherapy to treat cancer are at risk of damage to their healthy testicular tissue, which can lead to infertility in adulthood. Researchers are therefore investigating treatments to protect the testis during cancer treatment. Here, cells originating from rat testicles were cultured for 4 days and exposed to chemotherapy drugs with or without antioxidants for the final 2 days. Antioxidants can reduce cellular damage by inactivating toxic compounds. Here, antioxidants such as melatonin or <i>n</i>-acetylcysteine were tested against chemotherapy agents cisplatin, doxorubicin, or vincristine. Cultures were repeated four times, with cell survival measured at the end of culture. The antioxidants were not damaging and partially protected against cisplatin, although not doxorubicin. Surprisingly, <i>n</i>-acetylcysteine enhanced vincristine-induced damage. The results suggest that using antioxidants to protect the testis could have either beneficial or harmful effects when given alongside different chemotherapy drugs: this is important, considering that patients are often treated with multiple drugs.</p>","PeriodicalId":21128,"journal":{"name":"Reproduction & Fertility","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8788573/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39590536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Highly sensitive <i>in vitro</i> bioassay for luteinizing hormone and chorionic gonadotropin allowing their measurement in plasma.","authors":"Danièle Klett,&nbsp;Yves Combarnous","doi":"10.1530/RAF-21-0045","DOIUrl":"https://doi.org/10.1530/RAF-21-0045","url":null,"abstract":"<p><p>In previous studies, we had shown the synergistic effect of 10^-5 M forskolin (FSK) on the detection threshold of the cyclic AMP response to luteinizing hormones (LH) and chorionic gonadotropins (CG) from various species in the mouse Leydig tumor cell (mLTC) cell line. Independently, we started to study the effect of 10^-12-10^-6 M oxytocin (OXT) also on the cyclic AMP response to LH and CG preparations on these same cells and found an amplifying effect on the luminescence response caused by gonadotropins. The aim was then to explore the effects of 10^-12-10^-6 M OXT on the gonadotropin-induced cAMP response, in the presence or absence of 10 µM FSK to optimize the assay down to a sensitivity compatible with the detection of the circulating concentrations of these hormones in various species. Finally, the optimization relies on three independent phenomena: (1) the inhibition of nucleotide phosphodiesterase by IBMX (3-isobutyl-1-methylxanthine) to avoid cAMP degradation; (2) the strong synergy of 10 µM forskolin with low concentrations of LH or CG during the 1-h luminescence measurement; (3) the stimulatory effect of 10^-8M OXT on the amplitude of transfected cAMP-sensitive luciferase response. By doing this, the detectable concentrations are at the 1-10 pg/well (pM range) for the LHs and CGs from various species. The bioactivities of circulating LHs and CGs in blood or urine are therefore expected to be measurable in 10 µL-plasma samples from mammalian species and maybe others. Indeed, a preliminary study with equine and donkey plasma samples shows that the measured bioactivity was fully inhibited by a specific MAB against the receptor-binding region of equine LH (eLH) and equine CG (eCG), thus eliminating a possible response due to interfering substances other than eLH or eCG. From these data, it is expected that the bioactivity profiles of these hormones will be measurable in the blood of human, equine, and ovine species and very likely in rodents, ruminants, and hopefully in most other mammalian species.</p><p><strong>Lay summary: </strong>Luteinizing hormone (LH) plays a central role in controlling ovary and testicle functions in many animals, including humans. The highly sensitive method, known as an assay, described in this paper, measures the biological activity of LH in the blood of mammals. The assay is performed in culture of cells derived from mouse testicles in the presence of factors that diminish the detection threshold for LH. The knowledge of the bioactive LH concentration dynamics in the blood is very informative about the reproductive status of male and female mammals. This new <i>in vitro</i> bioassay provides a powerful tool to get this information.</p>","PeriodicalId":21128,"journal":{"name":"Reproduction & Fertility","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8788580/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39765385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Endometriosis - novel approaches and controversies debated.","authors":"W G Foster,&nbsp;M Leonardi","doi":"10.1530/RAF-21-0097","DOIUrl":"https://doi.org/10.1530/RAF-21-0097","url":null,"abstract":"Defined by the extrauterine growth of estrogendependent endometrial-like epithelial and stromal cells, endometriosis is a common gynecological and systemic inflammatory disease affecting approximately 179 million people assigned female at birth (predominately cisgender women) worldwide. Although most frequently detected in the pelvic cavity, endometriotic lesions can be found throughout the body. Three main phenotypes include endometriomas, superficial, and deep endometriosis. Lesion appearance is variable and dependent on the tissue on which it grows. Hallmark features of endometriosis include pelvic pain and infertility; however, some people with endometriosis remain asymptomatic. Endometriosis is a disease whose impact on the health care system exceeds that of caring for women with Crohn’s disease, asthma, migraines, and rheumatoid arthritis (Simoens et al. 2007, 2011, 2012, Klein et al. 2014). Although a relatively common disease with a high economic burden, endometriosis remains underfunded and under-researched (As-Sanie et al. 2019). While important advances have been made over the years in defining the pathophysiology of endometriosis, the cause of endometriosis remains ill-defined, diagnosis continues to present challenges and therapeutic options are suboptimal. Patients frequently report dissatisfaction with current therapeutic options prompting the search for alternative treatments including non-hormonal alternatives. In a special series that will be running in Reproduction and Fertility over the coming months, international experts have been recruited to provide insights and perspectives into the latest advances in endometriosis research and treatment. We strive to succeed with this special series in summarizing the current state of ‘leading edge’ research and opinion in endometriosis. Though not exhaustive, the topics and authors capture this moment in time in endometriosis research. Although widely recognized to be an estrogendependent disease, numerous physiological pathways are known to be dysregulated in people with endometriosis including cell adherence, attachment, proliferation, apoptosis, angiogenesis, and tissue remodeling enzyme expression (Hey-Cunningham et al. 2013). That endometriosis may have a heritable component is not a new concept (Saha et al. 2015); however, specific gene mutations and gene regulation continue to be explored. Indeed, the mechanisms regulating different pathways dysregulated in endometriotic tissues are beginning to be teased apart with increasing attention focused on mechanisms regulating gene expression including chromatin architecture, long ncRNA, micro-RNA, and piwi-RNA. The role of gonadal steroids in modulating the expression of epigenetic regulators of gene expression in endometriosis is poorly understood. Early in this special series, the relationship between gonadal steroids and genomic regulation is reviewed by Dr Philippa Saunders. Given the prominent role of estrogen and the use of androg","PeriodicalId":21128,"journal":{"name":"Reproduction & Fertility","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8788579/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39765388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spectral binning of cervicovaginal fluid metabolites improves prediction of spontaneous preterm birth and <i>Lactobacillus</i> species dominance.","authors":"Emmanuel Amabebe,&nbsp;Steven Reynolds,&nbsp;Dilly O C Anumba","doi":"10.1530/RAF-21-0065","DOIUrl":"https://doi.org/10.1530/RAF-21-0065","url":null,"abstract":"Lay summary Health-promoting bacteria (lactobacilli) exist in harmony with the vaginal environment. They are the predominant vaginal bacterial species during pregnancy. However, the possibility of infection and inappropriate immune response are linked with unprompted preterm delivery (PTD). Other invasive lactobacilli can alter the chemical environment of the vagina as they seek to promote their growth. This study measured the change in concentration of biochemical compounds and predominant bacterial species in vaginal fluid that are linked to PTD. The study recruited 300 healthy pregnant women who provided vaginal fluid samples during the second trimester. The women who harboured more of Lactobacillus jensenii over Lactobacillus crispatus (both reported as health-promoting bacteria) in their vaginal fluid had less lactate and glutamate and experienced more PTD. This suggests that lactate and glutamate levels in vaginal fluid may have clinical application in identifying which Lactobacillus species is most active. These chemical biomarkers could provide quick and accurate prediction of PTD risk in clinical settings.","PeriodicalId":21128,"journal":{"name":"Reproduction & Fertility","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ftp.ncbi.nlm.nih.gov/pub/pmc/oa_pdf/aa/3f/RAF-21-0065.PMC8788584.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39590535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Incidence of pregnancy loss and characterization of fetal development in red pandas.","authors":"Jenna Lowe,&nbsp;Erin Curry","doi":"10.1530/RAF-21-0079","DOIUrl":"https://doi.org/10.1530/RAF-21-0079","url":null,"abstract":"<p><p>Previous reports indicate that red pandas (<i>Ailurus fulgens styani</i>) may experience fetal loss during gestation; however, neither the rate nor timing of pregnancy failure has been described in this species. The objective of this study was to utilize ultrasound video and images collected between 2010 and 2020 at the Cincinnati Zoo and Botanical Garden to better characterize pregnancy loss and fetal development. Trans-abdominal ultrasound examinations were performed on six female red pandas over a 10-year period, resulting in 12 profiles. Pregnancy was diagnosed via ultrasound in 10 of 12 profiles, and 40.0% of pregnancies showed evidence of fetal loss prior to parturition. Pregnancy loss was classified into lost (2 of 10; 20.0%), in which no cubs were produced, or partial loss (2 of 10; 20.0%), in which two concepti were visualized via ultrasound, but only one cub was born. Fetal loss occurred between days 51 and 23 pre-partum. Fetal growth characteristics were documented, including skeletal ossification (occurring between days 32 and 27 pre-partum), crown-rump length, head length, cranial length, and fetal heart rate (173-206 b.p.m.). These findings provide novel insights into pregnancy loss, may serve as a reference for milestones of fetal development, and may be useful in diagnosing pregnancy and assessing pregnancy loss in red pandas.</p><p><strong>Lay summary: </strong>For many wildlife species, there is no non-invasive method of determining pregnancy; therefore, the rate of pregnancy loss oftentimes is unknown. Many red pandas in human care that are paired for breeding are observed exhibiting normal mating behaviors; however, only a relatively low proportion of females produce cubs. We utilized animals conditioned for ultrasound examination to diagnose pregnancy and characterize the incidence and timing of pregnancy loss. In total, 12 potential pregnancies were monitored, beginning after breeding season and ending ~2 weeks prior to anticipated cubbing. Of these, ten were (83.3%) were diagnosed as pregnant, with 40% undergoing either full or partial pregnancy loss. Fetal growth characteristics, such as body length and head size, are described which may be useful for monitoring pregnancies and estimating fetal age. Results of this study provide novel data on pregnancy loss in red pandas. Insights into the rate and timing of reproductive failure may illuminate causes and contributing factors, ultimately allowing for improvements in husbandry which may result in greater reproductive success of individuals recommended for breeding.</p>","PeriodicalId":21128,"journal":{"name":"Reproduction & Fertility","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8801018/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39765383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}