Age Of Embryo Research Articles

In vitro acute gamma radiation on tissue of pink and white lotus (Nelumbo nucifera Gaertn.) in Thailand

This research aimed to investigatethe age of embryos of pink and white lotus for in vitropropagation and examine the sensitivity of young lotus plants derived from tissue culture to acute gamma radiation. The seeds of both lotus varieties were 4-week, 6-week and 8-week-old embryos cultivated on solid MS medium. They were then transferred to solid MS medium supplemented with 3 mg/L BA. After culturing, the 6-week-old pink lotus embryos had an average maximum petiole length of 16.78 ± 1.01 cm and an average of 11.84 ± 0.44 roots/explant, while the 6-week-old white lotus embryos had an average maximum petiole length of 15.48 ± 0.68 cm and an average of 11.76 ± 0.70 roots/explant. Each young lotus plant produced one shoot. After treating the young lotus plants with liquid MS medium supplemented with 3 mg/L BA, both lotus varieties showed increased shoot numbers at 3.54 ± 0.13 and 3.40 ± 0.91 shoots/explant. Young lotus plants of both varieties were exposed to gamma radiation levels of 0, 20, 30 and 40 Gy. The LD50 value for pink lotus was 26.138 Gy, while the LD50 value for the white lotus was 32.031 Gy.The LD50 value will offer vital information for determining the optimal dosage of gamma radiation for both pink and white lotus in vitro.

O-203 Comparing viable and non-viable IVF early pregnancy measurements: does knowledge of gestational age using date of ET potentially change miscarriage diagnosis guidelines in IVF patients

Abstract Study question In IVF pregnancies with known embryo transfer (ET) dates, can gestational age as well as ultrasound measurements be used to diagnose miscarriage? Summary answer Early pregnancy measurements vary at fixed gestational ages based on ET. However, there is a specific time cut-off where an empty gestational sac indicates miscarriage. What is known already Current guidelines state that when ultrasound findings show a pregnancy of unknown viability, a repeat scan must be performed either 7 or 14 days later (depending on the presence of an embryo or gestation sac size) to confirm viability, irrespective of the LMP based gestational age. This definition only considers ultrasound measurements, and even when the pregnancy dates thought to be certain and based on day of ET date, there are no exceptions to this guidance. Study design, size, duration This was a retrospective cohort study within a London tertiary unit, Wolfson Clinic, Hammersmith Hospital, Imperial College Healthcare NHS Trust over a 36-month time period. We collated data from both fresh and frozen cycle IVF pregnancies over four years: Jan 1st 2019 to December 31st 2021. Participants/materials, setting, methods In this unit, patients undergoing fresh or frozen IVF cycles, have an embryo transfer at Day3-6 of development. We included any patient with a confirmed intrauterine pregnancy at first scan (5-8 weeks gestation) for analysis of pregnancy outcomes. The data collected included date of embryo transfer (ET), embryo age at transfer, and early pregnancy measurements using ultrasound. The endpoint was viability at the 11-14 week dating scan. Main results and the role of chance 1161 IVF embryo transfers were included in the study, 677 (58.3%) frozen and 484 (41.7%) fresh cycles. 892 (76.8%) remained viable at 11-14 weeks and 269 (23.2%) were non-viable. Pregnancies resulting in viable pregnancies had a range of CRL (≤16mm) and empty mean gestation sac diameter (MSD) (≤11mm) measurements at each expected age by ET date (≤8 weeks gestation). At 49 days CRL varied from 1mm to 17mm, and at 42 days empty MSD measurements varied from 7 to 18mm. This shows that a range in embryo and gestation sac sizes will be seen in subsequently shown to be viable pregnancies despite the apparent exact gestation being known based on ET. This may relate to both differing embryo growth rates and timing of implantation. A Kolmogorov-Smirnov test was applied to compare the viable and miscarriage cohort CRL measurements in relation to expected age by ET. The result: 0.610, p-value=1.33 x10-15, demonstrated a significant difference in embryo size between viable and non-viable pregnancies with known ET dates. All pregnancies where the scan showed an empty gestational sac (n = 157) at 47 days gestation by ET date, had a 100% positive predictive value with a 100% specificity (CI:90.1-100.0) for miscarriage. Limitations, reasons for caution The sample was powered to 0.9, significance level 0.05. Analysis demonstrated 100% positive predictive value with 100% specificity (CI:90.1-100.0), to confirm miscarriage with an empty gestation sac ≥47days age by ET date. A larger cohort size from different centres is needed to reduce the confidence interval and confirm the findings. Wider implications of the findings There is significant variation in CRL and MSD size between viable pregnancies of the same gestational age by ET. However, we found >47 days gestation an empty gestation sac resulted in miscarriage. If confirmed in larger studies this may permit women to be given an earlier definitive diagnosis of miscarriage. Trial registration number Audit registration GRM_104 Imperial Healthcare NHS Trust

P-782 Are pregnancy complications associated with the method of conception in female same-sex couples? Results of a retrospective, matched cohort study comparing ROPA and IUI

Abstract Study question Are pregnancies in female same-sex couples at a higher risk when using reception of oocytes from partner (ROPA) compared to those following intrauterine insemination (IUI)? Summary answer In female same-sex couples, pregnancies following ROPA demonstrated a higher incidence of preterm birth and first-trimester bleeding. What is known already Reception of Oocytes from PArtner (ROPA) enables both partners to contribute biologically to the desired pregnancy. However, oocyte donation, often performed in case of (premature) ovarian failure, is associated with an increased risk of hypertensive disorders of pregnancy/preeclampsia. Female same-sex couples typically comprising healthy, young women without underlying subfertility problems, are a priori at low absolute risk for pregnancy complications. Few studies have investigated the incidence of pregnancy complications and/or obstetrical outcomes in this specific group of women. Further insights and formal data could guide clinicians and patients in making informed decisions regarding the preferred method of conception. Study design, size, duration A retrospective, single-center, matched cohort study was performed including 577 unique female same-sex couples using donor semen who became pregnant after reproductive treatment (88 pregnancies following ROPA and 489 following IUI). None of the patients who opted for ROPA had (failed) IUI before. The study covered the period from January 2015 to January 2023. Participants/materials, setting, methods Pregnancies following ROPA were matched with pregnancies following IUI for age (+/-4 years), BMI (+/-4 kg/m2), parity (nulliparous vs multiparous) and date of embryo transfer/IUI (+/-1year) in a 1:1 ratio. Statistical Package for Social Sciences (SPSS) v26.0 was used for statistical analysis. Kolmogorov-Smirnov test was used to evaluate the normal distribution of continuous variables. Normally distributed data were analyzed with the student t-test and categorical variables were analyzed with the chi-square test. Main results and the role of chance After matching, 154 pregnancies (77 ROPA versus 77 IUI) were eligible for the study. Age (mean age 31.4±4.0 for ROPA versus 31.2±4.3 years for IUI, p = 0.48) and BMI (24.5±3.9 kg/m2 versus 25.2±4.4 kg/m2, for respectively ROPA versus IUI, p = 0.32) were comparable between groups after matching. Two ROPA pregnancies were excluded from further analysis due to elective termination of pregnancy (radiusaplasia and trisomy 21). Both groups experienced two stillbirths (two unexplained mors in utero, one chorioamnionitis and one intrapartum death). No significant difference in hypertensive disorders of pregnancy (HDP) (10.7% (8/75) versus 13.7% (10/73) for ROPA and IUI respectively, p = 0.53) or preeclampsia rates (11.0% (8/73) and 6.7% (5/75) for ROPA and IUI respectively, p = 0.33) was observed. ROPA-associated preeclampsia cases were often preterm (<37weeks’ gestation) compared to IUI (5/8 versus 1/5). ROPA pregnancies had a higher incidence of preterm birth (15.1% vs 1.3%,p<0.002) and first trimester bleeding was significantly more frequent (12.3% vs 0%,p<0.001). No statistically significant differences were observed between groups in neonatal weight, fetal structural malformations and cesarean section delivery rates. Limitations, reasons for caution The study is limited by its retrospective design and inherent bias. Despite reducing the sample size, matching enhanced study robustness. Recognized risk factors for hypertensive disorder of pregnancy, like the use of donor sperm, may mitigate differences associated with conception methods in this population. Wider implications of the findings The study points out potentially increased obstetrical risks following ROPA. These data are crucial to counsel and guide female same-sex couples in their decision regarding the method of conception. The risk of hypertensive disorders of pregnancy, specifically preterm preeclampsia, associated with ROPA warrants further attention, urging larger prospective studies. Trial registration number not applicable

P-090 Is preimplantation genetic testing for aneuploidy (PGT-A) necessary in the treatment strategy for ICSI with testicular sperm?

Abstract Study question Does the combination of testicular sperm extraction (TESE) and ICSI increase the risk of embryo aneuploidy? Summary answer Embryo aneuploidy occurrence is not increased when using testicular sperm and is not affected by the etiology of azoospermia. What is known already TESE-ICSI, especially in patients with non-obstructive azoospermia (NOA), has been reported to result in poor outcomes and difficulty in obtaining good blastocysts, which may be due to immature sperm retrieved by TESE. In addition, patients who require TESE have been shown to be at particularly high risk of chromosomally abnormal sperm. These factors may increase the risk of embryo aneuploidy in TESE-ICSI and contribute to poor outcomes. However, few reports have investigated the results of PGT-A following TESE-ICSI. This study was therefore designed to investigate whether using testicular sperm is more likely to result in embryo aneuploidy. Study design, size, duration This retrospective study included 81 couples and 197 TESE-ICSI cycles undergoing PGT-A (average maternal age: 38.1±5.4 years) between September 2016 and November 2023. Of the total cycles, 94 cycles were case of obstructive azoospermia (OA) and 53 cycles were cases of NOA. The etiologies of NOA included were unexplained (22 cycles), Klinefelter’s syndrome (KS) (10 cycles), post-chemotherapy (3 cycles), post-orchiopexy (11 cycles), and microdeletion of azoospermia factor (AZF) c on the Y chromosome (7 cycles). Participants/materials, setting, methods ICSI outcomes were compared between different etiologies (OA vs. NOA). A total of 356 blastocysts acquired were analyzed using PGT-A with next-generation sequencing (NGS). The PGT-A results were classified according to maternal age (<38, 38-41, >41 years) and paternal age (<40, ≥40 years). In addition, TESE-ICSI cycles were limited to the maternal age of < 38 years to remove the effect of maternal factors, the euploidy rates were compared between different etiologies or morphological grade. Main results and the role of chance The rates of fertilization and blastocyst formation for TESE-ICSI were significantly lower in NOA than OA (47.4% vs. 61.6%, P < 0.001 and 37.3% vs. 50.7%, P < 0.01, respectively). The rate of good-quality blastocyst (16.6% vs. 21.2%) was also lower, but not statistically significant. The euploidy rate of all evaluated TESE-ICSI embryos decreased with increasing maternal age (52.9% in < 38, 29.3% in 38-41, 10.0% in > 41 years), but was not affected by the paternal age (40.6% in < 40, 42.5% in ≥ 40 years). For cycles with the maternal age of < 38 years, the euploidy rate was not significantly different between OA and NOA patients (55.3% vs. 49.3%). In addition, the association between embryo euploidy and morphological grade (using Gardner’s classification, ≥BB for good-quality vs. <BB for poor-quality embryos) was evaluated, and the euploidy rate was significantly higher in good-quality embryos compared to poor-quality embryos (60.3% vs. 33.3%, P < 0.01). These results indicate the frequency of embryo aneuploidy in TESE-ICSI is comparable to commonly used ejaculated sperm. Furthermore, it suggests that embryo aneuploidy is dependent on maternal age or morphological grade of embryo, but not on paternal age or the etiology of azoospermia. Limitations, reasons for caution Patients with chromosomal abnormalities, i.e. KS, could not be evaluated due to the small number of cases and patients with chromosomal translocation were not included in this study. Therefore, the effects of male factors in NOA on embryo aneuploidy require extended investigation. Wider implications of the findings In TESE-ICSI, especially in the case of NOA, it is difficult to obtain good quality embryos due to poor ICSI outcomes. However, if good quality embryos are obtained, the euploidy rate is high and there is no need to perform PGT-A on the sole basis of using testicular sperm. Trial registration number not applicable

The typical developmental trajectory and energy requirements of Shitou goose during the embryonic stage

Low hatchability has been a persistent challenge in the goose industry. Establishing standard atlases and comprehending embryonic development patterns are essential to improving the hatching rates of goose eggs. However, comprehensive descriptions of normal atlases, embryonic development, and energy requirements in geese are lacking. In this study, a total of 120 fertile eggs from well-known large Shitou goose were incubated using 12 nesting purebred female geese. During hatching, both the temperature of the eggshells and the weight of eggs were recorded, and daily photographs of the embryos were captured to monitor their development closely. After hatching, count the number of pores per unit area by choosing eggs without sperm, dead embryos, or abnormal shells. Furthermore, 150 Shitou goose eggs were hatched by automatic incubator, with adjustments made based on observed normal developmental stages that incubated by female geese. The eggs were carefully opened to meticulously document embryonic morphology and create a detailed development map. Measurements were taken of the eye diameter, length of the lower beak, tarsometatarsus bone, and embryo length. Subsequently, an analysis was conducted to assess the calcium, phosphorus, crude protein, and crude fat content to study the energy requirements for embryo development. As a result, the hatch rate of the incubator reached 86.67%, and the cumulative water loss rate increased with embryo age. Notably, normally developing embryos displayed a significantly higher number of pores on the eggshell surface compared to dead embryos (P < 0.05). Additionally, embryonic body length, eyeball diameter, and lower beak length exhibited continuous growth until day 19 of incubation, while tarsometatarsus length increased steadily from days 12 to 31. Liver size measurement began on the 10th day of incubation, while both leg and chest muscles showed continuous growth from the 12th day. For energy demand, the embryo primarily relied on protein sourced from the egg yolk within the first 10 days of development. Afterward, the egg yolk provided both protein and fat for embryonic growth. In summary, this study has generated a comprehensive developmental map for Shitou goose embryos, offering valuable insights into their growth and morphological changes throughout the incubation period. This map can serve as a reference for optimizing machine incubation techniques to enhance goose egg hatching rates and provide fresh perspectives on the development of geese.

High-resolution transcriptome datasets during embryogenesis of plant-parasitic nematodes

Understanding the transcriptional regulatory characteristics throughout the embryogenesis of plant-parasitic nematodes is crucial for elucidating their developmental processes’ uniqueness. However, a challenge arises due to the lack of suitable technical methods for synchronizing the age of plant-parasitic nematodes embryo, it is difficult to collect detailed transcriptome data at each stage of embryonic development. Here, we recorded the 11 embryonic developmental time-points of endophytic nematode Meloidogyne incognita (isolated from Wuhan, China), Heterodera glycines (isolated from Wuhan, China), and Ditylenchus destructor (isolated from Jinan, China) species, and constructed transcriptome datasets of single embryos of these three species utilizing low-input smart-seq2 technology. The datasets encompassed 11 complete embryonic development stages, including Zygote, 2-cell, 4-cell, 8-cell, 24–44 cell, 64–78 cell, Comma, 1.5-fold, 2-fold, Moving, and L1, each stage generated four to five replicates, resulting in a total of 162 high-resolution transcriptome libraries. This high-resolution cross-species dataset serves as a crucial resource for comprehending the embryonic developmental properties of plant-parasitic nematodes and for identifying functional regulatory genes during embryogenesis.

Paternal care plasticity: males care more for early- than late-developing embryos in an arboreal breeding treefrog

BackgroundParental care benefits offspring but comes with costs. To optimize the trade-off of costs and benefits, parents should adjust care based on intrinsic and/or extrinsic conditions. The harm to offspring hypothesis suggests that parents should invest more in younger offspring than older offspring because younger offspring are more vulnerable. However, this hypothesis has rarely been comprehensively tested, as many studies only reveal an inverse correlation between parental care and offspring age, without directly testing the effects of offspring age on their vulnerability. To test this hypothesis, we studied Kurixalus eiffingeri, an arboreal treefrog with paternal care. We first performed a field survey by monitoring paternal care during embryonic development. Subsequently, we conducted a field experiment to assess the prevalence of egg predators (a semi-slug, Parmarion martensi) and the plasticity of male care. Finally, we conducted a laboratory experiment to assess how embryo age affects predation by P. martensi.ResultsOur results showed that (1) male attendance and brooding frequency affected embryo survival, and (2) males attended and brooded eggs more frequently in the early stage than in the late stage. The experimental results showed that (3) males increased attendance frequency when the predators were present, and (4) the embryonic predation by the semi-slug during the early was significantly higher than in the late stage.ConclusionsOur findings highlight the importance of paternal care to embryo survival, and the care behavior is plastic. Moreover, our results provide evidence consistent with the predictions of the harm to offspring hypothesis, as males tend to care more for younger offspring which are more vulnerable.

Histology Atlas of the Developing Mouse Respiratory System From Prenatal Day 9.0 Through Postnatal Day 30.

Respiratory diseases are one of the leading causes of death and disability around the world. Mice are commonly used as models of human respiratory disease. Phenotypic analysis of mice with spontaneous, congenital, inherited, or treatment-related respiratory tract abnormalities requires investigators to discriminate normal anatomic features of the respiratory system from those that have been altered by disease. Many publications describe individual aspects of normal respiratory tract development, primarily focusing on morphogenesis of the trachea and lung. However, a single reference providing detailed low- and high-magnification, high-resolution images of routine hematoxylin and eosin (H&E)-stained sections depicting all major structures of the entire developing murine respiratory system does not exist. The purpose of this atlas is to correct this deficiency by establishing one concise reference of high-resolution color photomicrographs from whole-slide scans of H&E-stained tissue sections. The atlas has detailed descriptions and well-annotated images of the developing mouse upper and lower respiratory tracts emphasizing embryonic days (E) 9.0 to 18.5 and major early postnatal events. The selected images illustrate the main structures and events at key developmental stages and thus should help investigators both confirm the chronological age of mouse embryos and distinguish normal morphology as well as structural (cellular and organ) abnormalities.

Protective effects of ferulic acid on embryonic development by improving antioxidant function in broilers embryo of thermal manipulation

This study aimed to elucidate the effects of broiler embryos soaked in ferulic acid (FA) solution on alleviating the negative impact of thermal manipulation (TM) on chicken embryo development and to provide a theoretical and experimental basis for applying TM and FA in the poultry feeding industry. A total of 120 broiler fertilized eggs were randomly divided into three groups: control group, TM group, and comprehensive group (TM + FA), with 40 eggs in each group. The TM group and the comprehensive group from the 7th embryonic age to the 16th embryonic age received TM for ten days, treated with a temperature of 39.5 °C and relative humidity of 65% for 18 h a day. In the comprehensive group, broiler embryos were immersed in FA solution at a concentration of 80 mg/L for 6 min at 16:00 every day from the 6th to the 8th embryo age. They were incubated continuously after being soaked until the chicks hatched. The results showed that the rates of dead embryos and weak chicks in the TM group were significantly higher than those in the control group and comprehensive group. Chick body temperatures of the TM group and comprehensive group were significantly lower than those of the control group. The heart weights of the TM group and comprehensive group were significantly lower than those of the control group, and the leg weights of the TM group were significantly decreased compared with those of the control group and comprehensive group. The SOD activity of serum in the comprehensive group was significantly higher than that in the control group and TM group, while the CAT activity of serum in the comprehensive group and control group was significantly higher than that in the TM group; however, there was no difference between the comprehensive group and control group. The activities of SOD and CAT in the liver were significantly higher than those of the TM group; however, the MDA content of the liver in the comprehensive group and control group was significantly lower than that of the TM group. The gene expression of Nrf2 and SOD in the comprehensive group and TM group was significantly higher than that in the control group; however, there was no significant difference between the comprehensive group and TM group. Soaking broiler embryonic eggs in an FA solution can improve the antioxidant capacity of the liver by upregulating Nrf2-Keap1 signal pathway-related gene expression. FA can effectively alleviate the side effects of TM on chicken embryos and does not impact the effects of TM.

Readmission following methotrexate treatment for tubal pregnancy.

To identify risk factors for readmission following methotrexate treatment for tubal pregnancy. A retrospective study undertaken in two tertiary medical centers, including all individuals with medically treated tubal pregnancy (N = 511), between December 2009 and June 2021. Individuals with and without readmission following methotrexate treatment were compared. The primary outcome was the readmission rate. Secondary outcomes included the rate of post-discharge gynecological emergency department visits, tubal rupture rate, and the eventual need for surgical treatment. Readmission following methotrexate treatment occurred in 224/511 patients (43.8%). Most readmissions were due to abdominal pain or suspicion of treatment failure. Readmitted individuals were more likely to have a history of pelvic inflammatory disease and pretreatment serum human chorionic gonadotropin (hCG) >2000 mIU/mL. Both factors remained significantly associated with higher readmission rates in a logistic regression analysis (adjusted odds ratio [OR] 6.28, 95% confidence interval [CI] 1.30-30.45, and adjusted OR 2.73, 95% CI 1.83-4.07, respectively) after adjustment for age, endometriosis, tubal pathology, abdominal pain, and presence of yolk sac or embryo at diagnosis. A dose-dependent association was observed between pretreatment serum hCG levels and readmission rate (P < 0.001). Pretreatment hCG levels were also associated with tubal rupture and the eventual need for surgical treatment (P < 0.001 for both). A prediction model using hCG was not sufficiently accurate to predict readmission risk. Readmission following methotrexate treatment for tubal pregnancy was independently associated with previous pelvic inflammatory disease and pretreatment serum hCG levels. The latter was also associated with surgical intervention rate.

The Differences in the Developmental Stages of the Cardiomyocytes and Endothelial Cells in Human and Mouse Embryos at the Single-Cell Level.

Our research focuses on expression patterns in human and mouse embryonic cardiomyocytes and endothelial cells at the single-cell level. We analyzed single-cell datasets containing different species, cardiac chambers, and cell types. We identified developmentally dynamic genes associated with different cellular lineages in the heart and explored their expression and possible roles during cardiac development. We used dynamic time warping, a method that aligns temporal sequences, to compare these developmental stages across two species. Our results indicated that atrial cardiomyocytes from E9.5 to E13.5 in mice corresponded to a human embryo age of approximately 5-6 weeks, whereas in ventricular cardiomyocytes, they corresponded to a human embryo age of 13-15 weeks. The endothelial cells in mouse hearts corresponded to 6-7-week-old human embryos. Next, we focused on expression changes in cardiac transcription factors over time in different species and chambers, and found that Prdm16 might be related to interspecies cardiomyocyte differences. Moreover, we compared the developmental trajectories of cardiomyocytes differentiated from human pluripotent stem cells and embryonic cells. This analysis explored the relationship between their respective developments and provided compelling evidence supporting the relevance of our dynamic time-warping results. These significant findings contribute to a deeper understanding of cardiac development across different species.

Thyroid-stimulating hormone levels are associated with estradiol levels and impact reproductive outcomes in preconceptionally euthyroid women undergoing their first IVF/ICSI cycles.

Controlled ovarian hyperstimulation (COH) has been reported to affect thyroid function; however, the impact of thyroid-stimulating hormone (TSH) levels during COH on embryo development and early reproductive outcomes has largely not been determined. Therefore, the aim of the present study was to investigate whether TSH levels are associated with COH and impact early reproductive outcomes in preconceptionally euthyroid women. This was a prospective cohort study. A total of 338 euthyroid women who underwent their first in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) treatment using the gonadotropin releasing hormone agonist (GnRH-a) protocol were included. Samples were collected at different representative time points for TSH and estradiol measurements. TSH levels significantly increased with the administration of Gn and maintained this tendency until the trigger day. Basal TSH levels increased along with basal estradiol levels and remained stable when estradiol levels were higher than 150 pmol/L. On the trigger day, TSH levels changed with increasing estradiol levels in the high-normal basal TSH group but not in the low TSH group. TSH did not impact clinical pregnancy or early pregnancy loss after adjusting for age, stage or number of embryos. Serum TSH levels change significantly during COH and are associated with significant changes in estradiol levels. However, euthyroid women with high-normal TSH levels showed similar development potential for inseminated embryos and early reproductive outcomes compared to those with low TSH levels.

Developing and validating a prediction model of live birth following single vitrified–warmed blastocyst transfer

Research questionCan the developed clinical prediction model offer an accurate estimate of the likelihood of live birth, involving blastocyst morphology and vitrification day after single vitrified–warmed blastocyst transfer (SVBT), and therefore assist clinicians and patients? Study designRetrospective cohort study conducted at a Spanish university-based reproductive medicine unit (2017–2021) including consecutive vitrified–warmed blastocysts from IVF cycles. A multivariable logistic regression incorporated key live birth predictors: vitrification day, embryo score, embryo ploidy status and clinically relevant variables, i.e. maternal age. ResultsThe training set involved 1653 SVBT cycles carried out between 2017 and 2020; 592 SVBT cycles from 2021 constituted the external validation dataset. The model revealed that female age and embryo characteristics, including overall quality and blastulation day, is linked to live birth rate in SVBT cycles. Stratification by vitrification day and quality (from day-5A to day-6 C blastocysts) applied to genetically tested and untested embryos. The model's area under the curve was 0.66 (95% CI 0.64 to 0.69) during development and 0.65 (95% CI 0.61 to 0.70) in validation, denoting moderate discrimination. Calibration plots showed strong agreement between predicted and observed probabilities. ConclusionBy incorporating essential predictors such as vitrification day, embryo morphology grade, age and preimplantation genetic testing for aneuploidy usage, this predictive model offers valuable guidance to clinicians and patients, enabling accurate forecasts of live birth rates for any given vitrified blastocyst within SVBT cycles. Additionally, it serves as a potentially indispensable laboratory tool, aiding in selecting the most promising blastocysts for optimal outcomes.

Developmental energetics in the oviparous corn snake, Pantherophis guttatus, confirms a conservative evolutionary pattern in snakes

Eggs of oviparous reptiles are ideal models for studying evolutionary patterns of embryonic metabolism since they allow tracking of energy allocation during development. Analyzing oxygen consumption of whole eggs throughout development indicates three patterns among reptiles. Embryos initially grow and consume oxygen exponentially, but oxygen consumption slows, or drops before hatching in some species. Turtles, crocodilians, and most lizards follow curves with initial exponential increases followed by declines, whereas embryonic snakes that have been studied exhibit a consistently exponential pattern. This study measured oxygen consumption of corn snake, Pantherophis guttatus, embryos to determine if this species also exhibits an exponential increase in oxygen consumption. Individual eggs, sampled weekly from oviposition to hatching, were placed in respirometry chambers for 24-h during which oxygen consumption was recorded. Embryos were staged and carcasses and yolk were weighed separately. Results indicate steady inclines in oxygen consumption during early stages of development, with a rapid increase prior to hatching. The findings support the hypothesis that embryonic oxygen consumption of snakes differs from most other non-avian reptiles. Total energy required for development was determined based on calorimetry of initial yolk compared to hatchlings and residual yolk and by integration of the area under the curve plotting oxygen consumption versus age of embryos. The cost of development estimates based on these two methods were 6.4 and 10.0 kJ, respectively. Our results emphasize the unique physiological aspects of snake embryogenesis and illustrate how the study of physiological characteristics can contribute to the broader understanding of reptilian evolution.

The association between pregnancy outcomes and frozen-thawed embryo transfer cycles based on D3 cell count in high-quality blastocysts.

To investigate the number of cells in D3-stage embryos of high-quality blastocysts as a contributing factor, to evaluate the clinical pregnancy outcomes in frozen-thawed embryo transfer cycles, and to determine the impact of D3-stage cell count on pregnancy outcomes. Patients under 38 years old who underwent frozen-thawed single high-quality blastocyst transfer at our center were selected. Based on the cell count of D3 cleavage-stage embryos forming blastocysts, patients were divided into three groups: ≤6 cells, 7-9 cells, and ≥10 cells. A multivariate regression analysis was used to establish the prediction model, analyzing the impact of different D3 cleavage-stage cell counts on clinical pregnancy outcomes to guide clinical laboratories in selecting blastocysts with the best pregnancy outcomes for transfer. This study identified a significant association between D3 cell count, blastocyst development stage, and embryo age. Embryos with a higher D3 cell count (≥10) were more likely to reach advanced blastocyst stages and form blastocysts by D5, whereas embryos with fewer D3 cells (≤6) were more likely to form blastocysts on D6. While D3 cell count significantly influenced blastocyst stage and timing of embryo development, no significant differences were observed between groups regarding clinical pregnancy, implantation, or live birth rates. Notably, embryos with fewer D3 cells exhibited a significantly lower miscarriage rate than other groups. Multivariate regression analysis showed a significant correlation between blastocyst stage, embryo age, and D3 cell count, particularly in D5 embryos and more advanced blastocysts. The increased miscarriage rate may be related to lower D3 cell count, and inadequate endometrial preparation was associated with poorer pregnancy outcomes. The type of infertility was also linked to D3 cell count, with secondary infertility patients showing more significant influencing factors. D3 cell count and related factors play a critical role in pregnancy outcomes during frozen-thawed high-quality blastocyst transfer cycles. Optimizing embryo age, selecting blastocysts at different stages, and refining endometrial preparation protocols are likely to enhance clinical pregnancy and live birth rates.

Effect of GnRH agonist down-regulation combined with hormone replacement treatment on reproductive outcomes of frozen blastocyst transfer cycles in women of different ages.

To investigate the effect of GnRH agonist (GnRH-a) down-regulation prior to hormone replacement treatment (HRT) to prepare the endometrium in frozen embryo transfer (FET) cycles in women of different ages. This was a retrospective study, and after excluding patients with adenomyosis, endometriosis, severe endometrial adhesions, polycystic ovary syndrome (PCOS), and repeated embryo implantation failures, a total of 4,091 HRT cycles were collected. Patients were divided into group A (<35 years old) and group B (≥35 years old), and each group was further divided into HRT and GnRHa-HRT groups. The clinical outcomes were compared between groups. There was no statistically significant difference in clinical outcomes between the HRT and GnRHa-HRT groups among women aged <35 years. In women of advanced age, higher rates of clinical pregnancy and live birth were seen in the GnRHa-HRT group. Logistic regression analysis showed that female age and number of embryos transferred influenced the live birth rate in FET cycles, and in women aged ≥ 35 years, the use of GnRH-a down-regulation prior to HRT improved pregnancy outcomes. In elderly woman without adenomyosis, endometriosis, PCOS, severe uterine adhesions, and RIF, hormone replacement treatment with GnRH agonist for pituitary suppression can improve the live birth rate of FET cycles.

Human Cardiac Development.

Many aspects of heart development are topographically complex and require three-dimensional (3D) reconstruction to understand the pertinent morphology. We have recently completed a comprehensive primer of human cardiac development that is based on firsthand segmentation of structures of interest in histological sections. We visualized the hearts of 12 human embryos between their first appearance at 3.5weeks and the end of the embryonic period at 8weeks. The models were presented as calibrated, interactive, 3D portable document format (PDF) files. We used them to describe the appearance and the subsequent remodeling of around 70 different structures incrementally for each of the reconstructed stages. In this chapter, we begin our account by describing the formation of the single heart tube, which occurs at the end of the fourth week subsequent to conception. We describe its looping in the fifth week, the formation of the cardiac compartments in the sixth week, and, finally, the septation of these compartments into the physically separated left- and right-sided circulations in the seventh and eighth weeks. The phases are successive, albeit partially overlapping. Thus, the basic cardiac layout is established between 26 and 32days after fertilization and is described as Carnegie stages (CSs) 9 through 14, with development in the outlet component trailing that in the inlet parts. Septation at the venous pole is completed at CS17, equivalent to almost 6weeks of development. During Carnegie stages 17 and 18, in the seventh week, the outflow tract and arterial pole undergo major remodeling, including incorporation of the proximal portion of the outflow tract into the ventricles and transfer of the spiraling course of the subaortic and subpulmonary channels to the intrapericardial arterial trunks. Remodeling of the interventricular foramen, with its eventual closure, is complete at CS20, which occurs at the end of the seventh week. We provide quantitative correlations between the age of human and mouse embryos as well as the Carnegie stages of development. We have also set our descriptions in the context of variations in the timing of developmental features.

Assessing the Influence of Maternal Age in Bovine Embryos and Oocytes: A Model for Human Reproductive Aging.

In the first weeks after fertilization, embryo mortality in cattle is significantly higher. It is well known that the age of the dam is one of the crucial factors affecting the quality of embryos and oocytes in many mammalian species. In older cattle, there are several evidences that embryo quality decreases, due to a decrease in ovarian reserve, a decrease in mtDNA and ATP, a decrease in progesterone levels, and due to susceptibility to genetic mutations. Herein, we intend to provide an updated summary of recent research on the effects of maternal age on embryos and oocytes of domestic cattle which are a widely used model species for human oocytes and early embryonic development.

Transcriptome-based comparison reveals key genes regulating allometry growth of forelimb and hindlimb bone in duck embryos

Allometric growth of the forelimb and hindlimb is a widespread phenomenon observed in vertebrates. As a typical precocial bird, ducks exhibit more advanced development of their hindlimbs compared to their forelimbs, enabling them to walk shortly after hatching. This phenomenon is closely associated with the development of long bones in the embryonic stage. However, the molecular mechanism governing the allometric growth of duck forelimb and hindlimb bones is remains elusive. In this study, we employed phenotypic, histological, and gene expression analyses to investigate developmental differences between the humerus (forelimb bone) and tibia/femur (hindlimb bones) in duck embryos. Our results revealed a gradual increase in weight and length disparity between the tibia and humerus from E12 to E28 (embryo age). At E12, endochondral ossification was observed solely in the tibia but not in the humerus. The number of differentially expressed genes (DEGs) gradually increased at H12 vs. T12, H20 vs. T20, and H28 vs. T28 stages consistent with phenotypic variations. A total of 38 DEGs were found across all 3 stages. Protein-protein interaction network analysis demonstrated strong interactions among members of HOXD gene family (HOXD3/8/9/10/11/12), HOXB gene family (HOXB8/9), TBX gene family (TBX4/5/20), HOXA11, SHOX2, and MEIS2. Gene expression profiling indicated higher expression levels for all HOXD genes in the humerus compared to tibia while opposite trends were observed for HOXA/HOXB genes with low or no expression detected in the humerus. These findings suggest distinct roles played by different clusters within HOX gene family during skeletal development regulation of duck embryo's forelimbs versus hind limbs. Notably, TBX4 exhibited high expression levels specifically in tibia whereas TBX5 showed similar patterns exclusively within humerus as seen previously across other species' studies. In summary, this study identified key regulatory genes involved in allometric growth of duck forelimb and hindlimb bones during embryonic development. Skeletal development is a complex physiological process, and further research is needed to elucidate the regulatory role of candidate genes in endochondral ossification.

Automated staging of zebrafish embryos with deep learning.

The zebrafish (Danio rerio) is an important biomedical model organism used in many disciplines. The phenomenon of developmental delay in zebrafish embryos has been widely reported as part of a mutant or treatment-induced phenotype. However, the detection and quantification of these delays is often achieved through manual observation, which is both time-consuming and subjective. We present KimmelNet, a deep learning model trained to predict embryo age (hours post fertilisation) from 2D brightfield images. KimmelNet's predictions agree closely with established staging methods and can detect developmental delays between populations with high confidence using as few as 100 images. Moreover, KimmelNet generalises to previously unseen data, with transfer learning enhancing its performance. With the ability to analyse tens of thousands of standard brightfield microscopy images on a timescale of minutes, we envisage that KimmelNet will be a valuable resource for the developmental biology community. Furthermore, the approach we have used could easily be adapted to generate models for other organisms.