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Copyright of Studia Ecologiae et Bioethicae is the property of Uniwerystet Kardynala Stefana Wyznskiege w Warzawie and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Studia Ecologiae et Bioethicae is the property of Uniwerystet Kardynala Stefana Wyznskiege w Warzawie and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Gene regulatory networks and tissue morphogenetic events drive the emergence of shape and function: the pillars of embryo development. Although model systems offer a window into the molecular biology of cell fate and tissue shape, mechanistic studies of our own development have so far been technically and ethically challenging. However, recent technical developments provide the tools to describe, manipulate and mimic human embryos in a dish, thus opening a new avenue to exploring human development. Here, I discuss the evidence that supports a role for the crosstalk between cell fate and tissue shape during early human embryogenesis. This is a critical developmental period, when the body plan is laid out and many pregnancies fail. Dissecting the basic mechanisms that coordinate cell fate and tissue shape will generate an integrated understanding of early embryogenesis and new strategies for therapeutic intervention in early pregnancy loss. [ABSTRACT FROM AUTHOR]

Summary: The objective of this study was to compare the rates of clinical pregnancy after the transfer of vitrified and thawed human embryos on days 3, 4 and 5 of embryonic development. In this retrospective study, the results of 148 embryo transfer cycles, using embryos frozen and thawed over the 3-year period between January 2016 and December 2018 at the Gülhane Training and Research Hospital Department of Gynecology and Obsterics Reproductive Medical Center of the University of Health Sciences, Ankara, Turkey were examined. Following embryo transfer – including 29 dissolved embryos frozen on day 3, 80 frozen on day 4, and 39 frozen on day 5 – results were examined in terms of clinical pregnancy rates. In this study, across all three groups, no significant differences were observed in terms of patient age, the number of oocytes collected, infertility reasons, the number of embryos dissolved, transfer day, or the number of embryos transferred. According to the transfer day, the rates of clinical pregnancy and ongoing pregnancy were significantly higher for embryos frozen on day 4 and transferred on day 5. Significantly higher rates of pregnancy and live birth were determined during in vitro fertilization (IVF) treatment with the freezing of human embryos on day 4 and the transfer of those embryos on day 5. [ABSTRACT FROM AUTHOR]

Gene editing refers to the site-specific modification of the genome, which mainly focuses on basic research, model organism construction and treatment and prevention of disease. Since the first application of CRISPR/Cas9 on the human embryo genome in 2015, the controversy over embryo gene editing (abbreviated as EGE in the following text) has never stopped. At present, the main contradictions focus on (1) ideal application prospects and immature technologies; (2) scientific progress and ethical supervision; and (3) definition of reasonable application scope. In fact, whether the EGE is 'God's scalpel' or 'Pandora's box' depends on the maturity of the technology and ethical supervision. This non-systematic review included English articles in NCBI, technical documents from the Human Fertilization and Embryology Authority as well as reports in the media, which performed from 1980 to 2018 with the following search terms: 'gene editing, human embryo, sequence-specific nuclease (SSN) (CRISPR/Cas, TALENT, ZFN), ethical consideration, gene therapy.' Based on the research status of EGE, this paper summarizes the technical defects and ethical controversies, enumerates the optimization measures and looks forward to the application prospect, aimed at providing some suggestions for the development trend. We should regard the research and development of EGE optimistically, improve and innovate the technology boldly and apply its clinical practice carefully. [ABSTRACT FROM AUTHOR]

Copyright of Przeglad Sejmowy is the property of Kancelaria Sejmu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

STUDY QUESTION Does embryo transfer medium containing hyaluronate (HA) promote the attachment phase of human embryo implantation? SUMMARY ANSWER HA-containing medium does not promote human blastocyst attachment to endometrial epithelial cells in vitro. WHAT IS KNOWN ALREADY Embryo transfer media containing high concentrations of HA are being used to increase implantation and live birth rates in IVF treatment, although the mechanism of action is unknown. STUDY DESIGN, SIZE, DURATION Expression of HA-interacting genes in frozen-thawed oocytes/embryos was assessed by microarray analysis (n  = 21). Fresh and frozen human blastocysts (n  = 98) were co-cultured with human endometrial epithelial Ishikawa cell layers. Blastocyst attachment and the effects of a widely used HA-containing medium were measured. PARTICIPANTS/MATERIALS, SETTING, METHODS Human embryos surplus to treatment requirements were donated with informed consent from several ART centres. Blastocyst-stage embryos were transferred at day 6 to confluent Ishikawa cell layers; some blastocysts were artificially hatched. Blastocyst attachment was monitored from 1 to 48 h, and the effects of blastocyst pre-treatment for 10 min with HA-containing medium were determined. MAIN RESULTS AND THE ROLE OF CHANCE Human embryos expressed the HA receptor genes CD44 and HMMR , hyaluronan synthase genes HAS1–3 , and hyaluronidase genes HYAL1–3 , at all stages of preimplantation development. Attachment of partially hatched blastocysts to Ishikawa cells at 24 and 48 h was related to trophectoderm grade (P  = 0.0004 and 0.007, respectively, n  = 34). Blastocysts of varying clinical grades that had been artificially hatched were all attached within 48 h (n  = 21). Treatment of artificially hatched blastocysts with HA-containing medium did not significantly affect attachment at early (1–6 h) or late (24 and 48 h) time points, compared with control blastocysts (n  = 43). LIMITATIONS, REASONS FOR CAUTION Using an adenocarcinoma-derived cell line to model embryo-endometrium attachment may not fully recapitulate in vivo interactions. The high levels of blastocyst attachment seen with this in vitro model may limit the sensitivity with which the effects of HA can be observed. WIDER IMPLICATIONS OF THE FINDINGS Morphological trophectoderm grade can be correlated with blastocyst attachment in vitro. HA-containing medium may increase pregnancy rates by mechanisms other than promoting blastocyst attachment to endometrium. STUDY FUNDING/COMPETING INTEREST(S) This work was funded by a grant from the Wellbeing of Women, the NIHR Local Comprehensive Research Network and NIHR Manchester Clinical Research Facility, the Department of Health Scientist Practitioner Training Scheme, and the Ministry of Higher Education, The State of Libya. None of the authors has any conflict of interest to declare. [ABSTRACT FROM AUTHOR]

The evolution and development of the head have long captivated researchers due to the crucial role of the head as the gateway for sensory stimuli and the intricate structural complexity of the head. Although significant progress has been made in understanding head development in various vertebrate species, our knowledge of early human head ontogeny remains limited. Here, we used advanced whole-mount immunostaining and 3D imaging techniques to generate a comprehensive 3D cellular atlas of human head embryogenesis. We present detailed developmental series of diverse head tissues and cell types, including muscles, vasculature, cartilage, peripheral nerves, and exocrine glands. These datasets, accessible through a dedicated web interface, provide insights into human embryogenesis. We offer perspectives on the branching morphogenesis of human exocrine glands and unknown features of the development of neurovascular and skeletomuscular structures. These insights into human embryology have important implications for understanding craniofacial defects and neurological disorders and advancing diagnostic and therapeutic strategies. [Display omitted] • 3D imaging reveals the developmental sequence of human head organs during gestation • Salivary gland morphogenesis is asymmetric and shows interindividual variability • Virtual reality and interactive 3D tools improve our understanding of human development • Hudeca.com, a web interface and image database to explore and learn human embryology Using advanced whole-mount immunostaining and 3D imaging, a comprehensive 3D cellular atlas of human head embryogenesis encompassing muscles, vasculature, cartilage, peripheral nerves, and exocrine glands is presented. The datasets are used to provide insights into the branching morphogenesis of exocrine glands and features of neurovascular and skeletomuscular structure development. [ABSTRACT FROM AUTHOR]

Abstract Background Morphometric and morphokinetic evaluation of in vitro cultured human embryos allows evaluation without time restriction and reduces intra- and inter-observer variability. Even though these technologies have been reported to improve the quality of cleavage stage embryo evaluation during fresh culture, possible advantages in the evaluation of cryopreserved embryos have been scarcely explored. This study aims to compare morphometric and morphokinetic parameters between slow frozen and vitrified embryos and to determine their relationship to embryo survival and implantation rate (IR) after thawing/warming. Methods During fresh culture, morphometric characteristics (Total Cell Volume (TCV), symmetry, fragmentation and number of blastomeres) were measured in 286 thawed/warmed embryos. Likewise, after thawing/warming, similar morphometric characteristics were measured in 135 survived embryos. Moreover, morphokinetic parameters (time to mitosis resumption and time to compaction) were measured in 90 embryos after thawing/warming. Then, using linear regression, we investigated the differences between vitrified and slow frozen embryos and the relation of the measured characteristics to embryo survival and IR. Statistical corrections were applied to account for data clustering and for multiple testing. Results Vitrified embryos resume mitosis and start compaction significantly earlier than slow frozen embryos. Mitosis resumption rate was 82% for vitrified and 63% for slow frozen embryos and median time to mitosis resumption was 7.6 h and 13.1 h (p = 0.02), respectively. Compaction rate was 62% in vitrified and only 23% in slow frozen embryos. Median time to compaction was 18.1 h for vitrified embryos but, for slow frozen could not be computed since less than half of the slow frozen embryos reached compaction (p = 0.0001). Moreover, intact embryos resume mitosis significantly earlier than not intact ones regardless of the freezing method (rate: 79% vs. 66%, median time: 7.6 h vs 14.6 h, respectively, p = 0.03). Regarding morphometrics, slow frozen embryos showed lower TCV and higher blastomere symmetry after thawing than vitrified embryos despite having similar blastomere number. IR was related to blastomere number at cryopreservation in slow frozen embryos, but not in vitrified ones. Conclusions Interestingly, vitrified/warmed embryos undergo mitosis resumption and compaction significantly earlier than slow frozen/thawed embryos. However, the clinical use of this morphokinetic parameters still remains to be investigated in larger studies. Trial registration Retrospectively registered on December 15, 2015 NCT02639715 .

Abstract β-Thalassemia is a global health issue, caused by mutations in the HBB gene. Among these mutations, HBB −28 (A>G) mutations is one of the three most common mutations in China and Southeast Asia patients with β-thalassemia. Correcting this mutation in human embryos may prevent the disease being passed onto future generations and cure anemia. Here we report the first study using base editor (BE) system to correct disease mutant in human embryos. Firstly, we produced a 293T cell line with an exogenous HBB −28 (A>G) mutant fragment for gRNAs and targeting efficiency evaluation. Then we collected primary skin fibroblast cells from a β-thalassemia patient with HBB −28 (A>G) homozygous mutation. Data showed that base editor could precisely correct HBB −28 (A>G) mutation in the patient’s primary cells. To model homozygous mutation disease embryos, we constructed nuclear transfer embryos by fusing the lymphocyte or skin fibroblast cells with enucleated in vitro matured (IVM) oocytes. Notably, the gene correction efficiency was over 23.0% in these embryos by base editor. Although these embryos were still mosaic, the percentage of repaired blastomeres was over 20.0%. In addition, we found that base editor variants, with narrowed deamination window, could promote G-to-A conversion at HBB −28 site precisely in human embryos. Collectively, this study demonstrated the feasibility of curing genetic disease in human somatic cells and embryos by base editor system.

Objective After the introduction of assisted reproductive techniques, human embryos were officially introduced into laboratories and now thousands of them are cryopreserved in such settings. Embryonic stem cells and the future application of such cells in the treatment of disease opened the door to further research on human embryos. These developments raise many ethical issues, some of which have religious aspects. The main question is: what is the embryo? Should we consider it a human being? Thus, the purpose of this study was to investigate attitudes towards the personhood of the embryo. Materials and Methods In this cross sectional study, 203 infertile patients (n=406), 54 clinic staff and 49 embryo researchers, selected using convenience sampling at the Royan Institute, completed a questionnaire on personhood of human embryo. The questionnaire had been developed following qualitative research and had satisfied face and content validity tests. Results At the pre-implantation stage the majority of participants in all three groups considered the human embryo as "not a human being". Also, at the post-implantation stage of development, the majority of infertile couples and clinic staff considered the embryo as "not a human being" but, half the researchers (51%) considered the embryo in this stage as a "potential human". Half of the infertile couples considered the human fetus before ensoulment time (19th week of pregnancy according to the Shiite Islamic scholars) as "not-human being", while more than half of researchers (55.1%) considered it as a "potential human". Conclusion Ensoulment time is a major and important border for personhood. Most infertile couples and clinic staff consider the human embryo as "not a human being" but majority of all study participants considered the human fetus to be a complete human after ensoulment time.

Objective: To study the possibility of increasing the cooling rates of the vitrification procedure in a closed system with the use of aluminum oxide as an intermediate coolant., Design: Case report., Subjects: Six patients undergoing procedures for assisted reproduction., Intervention: Comparative studies of cryopreservation of donor embryos with aluminum oxide as an intermediate cooling agent (experimental group) and without it (control group) have been performed. After thawing, the embryo morphology and its potential to develop to the blastocyst stage have been assessed. The methodology was then applied to clinical practice., Main Outcome Measures: Twenty embryos of 6 patients have been vitrified on day 4 after fertilization with the use of aluminum oxide as an intermediate coolant. Fourteen of them have been thawed. All have displayed normal morphology and 10 have formed blastocysts after 24 hours of culture. Four of the patients received embryo transfer with 2 embryos and the other 2 with single embryos., Results: After preliminary comparative studies of embryos frozen with aluminum oxide and a control group, the results showed no statistically significant difference between their quality and potential to reach to blastocyst stage. That gave us ground to apply the methodology in clinical practice. After the embryo transfer, 3 clinical pregnancies with successful live births have been obtained., Conclusions: Our experience shows that preimplantation embryos can be cryopreserved aseptically, in closed systems, with the help of aluminum oxide as an intermediate coolant., Competing Interests: P.T. has nothing to disclose. E.H. has nothing to disclose. N.P. has nothing to disclose. T.M. has nothing to disclose., (© 2024 The Authors.)

While studied extensively in model systems, human gastrulation remains obscure. The scarcity of fetal biological material as well as ethical considerations limit our understanding of this process. In vitro attachment of natural blastocysts shed light on aspects of the second week of human development in the absence of the morphological manifestation of gastrulation. Stem cell-derived blastocyst models, blastoids, provide the opportunity to reconstitute pre- to post-implantation development in vitro. Here we show that upon in vitro attachment, human blastoids self-organize a BRA + population and undergo gastrulation. Single-cell RNA sequencing of these models replicates the transcriptomic signature of the human gastrula. Analysis of developmental timing reveals that in both blastoid models and natural human embryos, the onset of gastrulation as defined by molecular markers, can be traced to timescales equivalent to 12 days post fertilization. In all, natural human embryos and blastoid models self-organize primitive streak and mesoderm derivatives upon in vitro attachment., Competing Interests: Declaration of interests A.H.B. is the co-founder of RUMI Scientific and OvaNova. A.H.B. and E.A.R.-O. are shareholders of RUMI Scientific., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Single-cell RNA sequencing (scRNA-seq) revolutionized our understanding of the molecular processes of early development and provided us with the means to capture biological heterogeneity and assess the cellular composition in early embryos. Comparative analysis of the transcriptional landscapes of embryos with single-cell resolution allows us to better understand and improve stem-cell-based embryo models. However, proper comparison between different single-cell datasets acquired by different laboratories and through different technologies is imperative for adequate analysis and findings. In this chapter, we focus on the analysis of human blastoids, which model the blastocyst, and their integrative analysis with human embryo datasets and a 2D in vitro early development model system dataset, which models epiblast, extraembryonic mesoderm, and trophoblast cells., (© 2023. Springer Science+Business Media, LLC.)

The development process of human embryo until blastocyst is well understood during the past 30 years, however, embryogenesis from blastocyst to pre-gastrulation was still remained a "black box". Limited by research materials and culture technologies, the "black box" is still unopened. We recently established an extended three-dimensional (3D) culture system of human blastocysts (Xiang et al., Nature 577(7791):537-542, 2020). The 3D embryo culture system could enable human blastocyst growing up to early primitive streak anlage stage in vitro. Here, we introduce the detail protocol and notes of culturing human 3D embryos., (© 2023. Springer Science+Business Media, LLC.)

The human extraembryonic mesoderm (EXM) is an important tissue in the postimplantation embryo which is specified before gastrulation in primates but not in rodents. EXM is mesenchymal and plays an important role in embryogenesis, including early erythropoiesis, and provides mechanical support to the developing embryo. Recently, it has been shown that self-renewing extraembryonic mesoderm cells (EXMCs) can be modeled in vitro by using human naive pluripotent stem cells. Here, we present a detailed step-by-step protocol to induce EXMCs from naive pluripotent stem cells in vitro., (© 2023. Springer Science+Business Media, LLC.)

The CRISPR-Cas system is a powerful tool for in vivo editing the genome of most organisms, including man. During the years this technique has been applied in several fields, such as agriculture for crop upgrade and breeding including the creation of allergy-free foods, for eradicating pests, for the improvement of animal breeds, in the industry of bio-fuels and it can even be used as a basis for a cell-based recording apparatus. Possible applications in human health include the making of new medicines through the creation of genetically modified organisms, the treatment of viral infections, the control of pathogens, applications in clinical diagnostics and the cure of human genetic diseases, either caused by somatic (e.g., cancer) or inherited (mendelian disorders) mutations. One of the most divisive, possible uses of this system is the modification of human embryos, for the purpose of preventing or curing a human being before birth. However, the technology in this field is evolving faster than regulations and several concerns are raised by its enormous yet controversial potential. In this scenario, appropriate laws need to be issued and ethical guidelines must be developed, in order to properly assess advantages as well as risks of this approach. In this review, we summarize the potential of these genome editing techniques and their applications in human embryo treatment. We will analyze CRISPR-Cas limitations and the possible genome damage caused in the treated embryo. Finally, we will discuss how all this impacts the law, ethics and common sense.

Objective: The presence of a sex related metabolic difference in glucose utilization and, on the other hand, different developmental kinetic rates in human preimplantation embryos, has been previously observed, however, the correlation between these two events is unknown. Oxidative stress (OS) induced by higher glucose consumption appears to be a possible cause for the delayed development rate in female embryos. We examined the correlation between glucose consumption and total antioxidant capacity (TAC) concentration in individual embryo culture media for both male and female embryos. Materials and Methods: In this cross-sectional study, we evaluated high quality embryos from 51 patients that underwent intracytoplasmic sperm injection (ICSI) and preimplantation genetic diagnosis (PGD) at the Royan Institute between December 2014 and September 2017. The embryos were individually cultured in G-2TM medium droplets at days 3-5 or 48 hours post PGD. We analysed the spent culture media following embryo transfer for total antioxidant capacity (TAC) and any remaining glucose concentrations through fluorometric measurement by chemiluminecence system which indirectly was used for measurement of glucose consumed by embryos. Results: The results showed that female embryos consumed more glucose which was associated with decreased TAC concentration in their culture medium compared to male embryos. The mean of glucose concentration consumed by the female embryos (30.7 ± 4.7 pmol/embryo/hour) was significantly higher than that of the male embryos (25.3 ± 3.3 pmol/embryo/hour) (P<0.001). There were significantly lower levels of TAC in the surrounding culture medium of female embryos (22.60 ± 0.19 nmol/μl) compared with male embryos (24.74 ± 0.27 nmol/μl, P<0.01). Conclusion: This finding highlighted the utilization of sex dependent metabolic diversity between preimplantation embryos for non-invasive sex diagnosis and suggests the TAC concentration as a potential noninvasive biomarker for prediction of sex. [ABSTRACT FROM AUTHOR]

The bioethical principle of autonomy is problematic regarding the future of the embryo who lacks the ability to self-advocate but will develop this defining human capacity in time. Recent experiments explore the use of clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 for germline engineering in the embryo, which alters future generations. The embryo's inability to express an autonomous decision is an obvious bioethical challenge of germline engineering. The philosopher Joel Feinberg acknowledged that autonomy is developing in children. He advocated that to reserve this future autonomy, parents should be guided to make ethical decisions that provide children with open futures. Here, Feinberg's 1980 open future theory is extended to the human embryo in the context of CRISPR germline engineering. Although the embryo does not possess the autonomous decision-making capacity at the time of germline engineering, the parental decision to permanently change the unique genetic fabric of the embryo and subsequent generations disregards future autonomy. Therefore, germline engineering in many instances is objectionable considering Feinberg's open future theory. [ABSTRACT FROM AUTHOR]

Background: At birth, the ductus arteriosus (DA) merges with the aortic arch in the slightly caudal side of the origin of the left subclavian artery (SCA). Since the SCAs (7th segmental arteries) were fixed on the level of the 7th cervical-first thoracic vertebral bodies, the confluence of DA should migrate caudally. We aimed to describe timing and sequence of the topographical change using serial sagittal sections of 36 human embryos and foetuses (CRL 8-64 mm; 5-10 weeks), Those made easy evaluation of the vertebral levels possible in a few section.Materials and Methods: The DA or 6th pharyngeal arch artery seemed to slide down in front of the sympathetic nerve trunk along 1.0-1.2 mm from the second cervical vertebral level at 5-6 weeks and, at 6 weeks (CRL 14-17 mm), the DA confluence with aorta reached the 7th cervical level. Because of the highly elongated common carotid artery, the sliding of DA confluence seemed to be much shorter than the cervical vertebrae growing from 1 mm to 2.4 mm.Results: At the final topographical change at 6-7 weeks, the DA confluence further descended to a site 1-vertebral length below the left SCA origin. From 6 to 9 weeks, a distance from the top of the aortic arch to the left SCA origin was almost stable: 0.3-0.5 mm at 6 weeks and 0.4-0.6 mm at 9 weeks.Conclusions: The heart descent and the caudal extension of the trachea and bronchi, those occurred before the DA sliding, were likely to be a major driving force for the sliding. [ABSTRACT FROM AUTHOR]

Objective: It is widely accepted that aging decreases women's fertility capacity. The aim of this study was to assess correlations between maternal age and the morphokinetic parameters and cleavage pattern of embryos. Methods: The morphokinetics of embryos derived from women <30, 30-35, 36-40, and >40 years of age were compared retrospectively in terms of time of second polar body extrusion, time of pronuclei appearance, time of pronuclei fading, and time of two to eight discrete cells (t2-t8). Furthermore, abnormal cleavage patterns such as uneven blastomeres at the two-cell stage, cell fusion (Fu), and trichotomous mitoses (TM) were assessed. Results: Only t5 occurred later in women aged 36-40 and >40 years when compared with those aged <30 and 30-35 years (p<0.001). Other morphokinetic timing parameters, as well the presence of uneven blastomeres, were comparable between the groups (p>0.05). However, Fu and TM were more common in women aged >40 years than in younger women (p<0.001). Conclusion: Maternal age was correlated with the cleavage pattern of embryos. Therefore, evaluating embryo morphokinetics may contribute to optimal embryo selection, thereby increasing fertility in patients with advanced maternal age. [ABSTRACT FROM AUTHOR]

The human nervus terminalis (terminal nerve) and the nerves to the vomeronasal organ (VNON) are both associated with the olfactory nerves and are of major interest to embryologists. However, there is still limited knowledge on their topographical anatomy in the nasal septum and on the number and distribution of ganglion cells along and near the cribriform plate of the ethmoid bone. We observed serial or semiserial sections of 30 fetuses at 7–18 weeks (crown rump length [CRL], 25–160 mm). Calretinin and S100 protein staining demonstrated not only the terminal nerve along the anterior edge of the perpendicular lamina of the ethmoid, but also the VNON along the posterior edge of the lamina. The terminal nerve was composed of 1–2 nerve bundles that passed through the anterior end of the cribriform plate, whereas the VNON consisted of 2–3 bundles behind the olfactory nerves. The terminal nerve ran along and crossed the posterior side of the nasal branch of the anterior ethmoidal nerve. Multiple clusters of small ganglion cells were found on the lateral surfaces of the ethmoid’s crista galli, which are likely the origin of both the terminal nerve and VNON. The ganglions along the crista galli were ball-like and 15–20 μm in diameter and, ranged from 40-153 in unilateral number according to our counting at 21-μm-interval except for one specimen (480 neurons; CRL, 137 mm). An effect of nerve degeneration with increasing age seemed to be masked by a remarkable individual difference. [ABSTRACT FROM AUTHOR]

• A new method of statistical shape modeling for nested objects is proposed. • Our shape representation method enables the model to preserve a nested structure. • Our method can be applied to any number of shapes. • Modeling of the brain, ventricles, and choroid plexus of human embryos was performed. • Our model showed a higher generalization and specificity ability and no leakage. In this study, we propose a method for constructing a multishape statistical shape model (SSM) for nested structures such that each is a subset or superset of another. The proposed method has potential application to any pair of shapes with an inclusive relationship. These types of shapes are often found in anatomy, such as the brain surface and ventricles. The main contribution of this paper is to introduce a new shape representation called log-transformed level set function (LT-LSF), which has a vector space structure that preserves the correct inclusive relationship of the nested shape. In addition, our method is applicable to an arbitrary number of nested shapes. We demonstrate the effectiveness of the proposed shape representation by modeling the anatomy of human embryos, including the brain, ventricles, and choroid plexus volumes. The performance of the SSM was evaluated in terms of generalization and specificity ability. Additionally, we measured leakage criteria to assess the ability to preserve inclusive relationships. A quantitative comparison of our SSM with conventional multishape SSMs demonstrates the superiority of the proposed method. [ABSTRACT FROM AUTHOR]

Present study analyses the co-localisation of RIP5 with FGFR1, FGFR2 and HIP2 in the developing kidney, as RIP5 is a major determinant of urinary tract development, downstream of FGF-signaling. Paraffin embedded human kidney tissues of 16 conceptuses between the 6th-22th developmental week were analysed using double-immunofluorescence method with RIP5/FGFR1/FGFR2 and HIP2 markers. Quantification of positive cells were performed using Kruskal–Wallis test. In the 6th week of kidney development RIP5 (89.6%) and HIP2 (39.6%) are strongly expressed in the metanephric mesenchyme. FGFR1 shows moderate/strong expression in the developing nephrons (87.3%) and collecting ducts (70.5%) (p < 0.05). RIP5/FGFR1 co-localized at the marginal zone and the ureteric bud with predominant FGFR1 expression. FGFR2 (26.1%) shows similar expression pattern as FGFR1 (70.5%) in the same kidney structures. RIP5/FGFR2 co-localized at the marginal zone and the collecting ducts (predominant expression of FGFR2). HIP2 is strongly expressed in collecting ducts (96.7%), and co-localized with RIP5. In 10th week, RIP5 expression decrease (74.2%), while the pattern of expression of RIP5 and FGFR1 in collecting ducts (33.4% and 91.9%) and developing nephrons (21.9% and 32.4%) (p < 0.05) is similar to that in the 6th developmental week. Ureter is moderately expressing RIP5 while FGFR1 is strongly expressed in the ureteric wall. FGFR2 is strongly expressed in the collecting ducts (84.3%) and ureter. HIP2 have 81.1% positive cells in the collecting duct. RIP5/FGFR1 co-localize in collecting ducts and Henley's loop. The expression pattern of RIP5, FGFR1, FGFR2 and HIP2 in the human kidney development might indicate their important roles in metanephric development and ureteric muscle layer differentiation through FGF signaling pathways. [ABSTRACT FROM AUTHOR]

In contrast to embryo donation, the permissibility of 2PN cell donation is highly controversial in Germany. This article is based on there being a legal loophole with respect to 2PN cell donation, which results from an inconsistency within the Embryo Protection Act on the normative status of 2PN cells. Following that thesis, the article argues that, on the basis of the normative criterion totipotency (i.e. the capacity to develop into a born human being), 2PN cells should also be considered human embryos within the meaning of the Act and thereby be protected by that Act in the same way as embryos. However, the normative assumption that 2PN cells should already be endowed with human dignity and the right to life has absurd consequences. Moreover, the consistent continuation of the Embryo Protection Act, as well as of the underlying ethical position or argumentation (i.e. the potentiality argument), leads to the even more absurd consequence of having to place every human somatic cell under the protection of human dignity and the right to life. As totipotency or the developmental potential therefore cannot delimit entities considered worthy of protection (i.e. human embryos) from entities considered not worthy of protection (i.e. 2PN cells, gametes, hESC, hiPSC and human somatic cells), it is not a suitable normative criterion. As a paradigmatic case, 2PN cell donation demonstrates that by retaining this normative criterion the now obsolete German Embryo Protection (Act) ultimately undermines itself. [ABSTRACT FROM AUTHOR]

Abstract The aim of this study was to examine the spatio-temporal appearance of different neuronal cell subtypes by analyzing expression patterns of several neuronal markers (calretinin, neurofilament 200 (NF200), vanilloid receptor 1(VR1) and calcitonin gene-related peptide (CGRP)) of the embryonic human spinal cord (SC). Developing human SCs from 11 human conceptuses beetwen 5–10 developmental weeks (DW) were examined by light and electron microscopy and immunofluorescence. Light and electron microscopy revealed different embryonic stages of recognizable structure of the SC. NF200, CGRP and VR1 positive cells were observed in SCs during 5th–6th DW. NF200 was predominantly expressed in the ventral part, indicating presence of motoneurons. As development advanced, NF200 was mainly expressed in the marginal zone. Expression of CGRP was intense during all of the investigated periods, predominantly during the 5th–6th DW pointing to neural sensory differentiation, as opposed to the last DW when reduced expression of CGRP in the marginal layer indicated the terminations of the sensory afferents. Expression of VR1 was highest in the intermediate zone, at the beginning and at the end of the investigated periods, pointing to VR1 spatial pattern in the visceral afferents in the grey matter, while the first signs of calretinin were found in the 9th–10th DW ventrally. Delineating the relationships between factors involved in processes of neuronal differentiation as well as spatial and temporal arrangement of SC interrelated neurons can provide a useful information about normal SC development as well as the insight in possible causes of anomalies and disorders during embryonic life. [ABSTRACT FROM AUTHOR]

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Despite advances to engineer transplantable hematopoietic stem and progenitor cells (HSPCs) for research and therapy, an in-depth characterization of the developing human hematopoietic system is still lacking. The human embryonic liver is at the crossroad of several hematopoietic sites and harbors a complex hematopoietic hierarchy, including the first actively dividing HSPCs that will further seed the definitive hematopoietic organs. However, few are known about the phenotypic and functional HSPC organization operating at these stages of development. In this study, using a combination of four endothelial and hematopoietic surface markers, that is, the endothelial-specific marker vascular endothelial-cadherin (Cdh5, CD144), the pan-leukocyte antigen CD45, the hemato-endothelial marker CD34, and the angiotensin-converting enzyme (ACE, CD143), we identified distinct HSPC subsets, and among them, a population co-expressing the four markers that uniquely harbored an outstanding proliferation potential both ex vivo and in vivo. Moreover, we traced back this population to the yolk sac (YS) and aorta-gonad-mesonephros (AGM) sites of hematopoietic emergence. Taken together, our data will help to identify human HSPC self-renewal and amplification mechanisms for future cell therapies. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs) are emerging as important in human embryo implantation, and we present here a review of the literature from a clinical perspective. Implantation involves complex interactions between the blastocyst and endometrium. miRNAs have been shown to be differentially expressed in implanted compared with non-implanted blastocysts and euploid compared with aneuploid blastocysts. Further, miRNAs are differentially expressed in proliferative compared with decidualized endometrium, and in receptive compared with pre-receptive endometrium. miRNAs are also differentially expressed in endometrium of women who failed implantation, and in endometrium of women with recurrent implantation failure. Due to the complexity of miRNA signaling, studies have suffered from inconsistency in reproducibility of results. However, miRNAs show potential as biomarkers in the pursuit of more reliable prediction of embryo implantation. [ABSTRACT FROM AUTHOR]

For centuries, the embryo has remained invisible, fueling multiple beliefs, mysteries and representations. In less than a few decades, modern science has totally revolutionized our vision of the embryo. The development of fetal ultrasound gave us the first in utero images, permeating the characteristic representation of "homo novus" in the collective unconscious. The invisible embryo has become real, the fruit of a medical technique and a source of hope for many infertile couples. The "test tube baby" was born when it consisted of only a few cells. The embryo has become an object of fantasy; it sometimes expresses itself as a defender of the feminist movement, or in the campaign against smoking, and it has found a place in the anti-abortion movement. Increasingly desired, this being-in-the-making is increasingly vulnerable and now, at the beginning of the twenty-first century, is seen both as a monster and a superhero. [ABSTRACT FROM AUTHOR]

Studying early development in human embryo is both an ethical and a technical challenge. In addition, a strict legislation surrounds research on human embryo. As it is difficult to study the post-implantation embryonic development in vivo and without enough efficient culture method previously available ex vivo, in vitro culture models have been proposed for studying morphogenesis. These models, initially developed on mouse embryo and more recently on human embryo, allowed analyzing the embryo organization at this crucial periimplantation period. However, it remained a "black box" because it takes place as the blastocyst is implanting into the uterus. The development of new techniques of image analysis and the improvement of culture models, thanks to the advance of both the culture media composition and the three dimensions (3D) supports development, made it possible to reveal the growth and morphogenesis of the embryo in in vitro very prolonged culture methods, until the 14th day post-fertilization. More precisely, and to summarize, these recent studies paved the way of a better understanding of the embryo development from pluripotent cells to a threedimensional polarized cellular organization. The transition from the blastocyst to the didermal disc surrounded by the two layers : the epiblast and the primitive endoderm in the human embryo or egg-cylinder stage in the mouse, a structure composed of the pro-amniotic cavity delimited by the epiblast and the extra-embryonic endoderm surrounded by the primitive endoderm. In the course of peri-implant development, two major modifications concerning embryonic morphogenesis take place with the establishment of the anteroposterior axis in 2D and its evolution towards a 3D structure at the time of gastrulation. These technical significant progress report the ability of the human embryo, as previously proved in mice, to develop in the absence of maternal tissue. Recent studies emphasize the autonomy of the embryo in this early organization. Nevertheless these technical advances, allowing an embryonic culture at increasingly advanced stages, raise a certain number of ethical issues. [ABSTRACT FROM AUTHOR]

Since the late 1960s, and as a result of the improvement of in vitro fertilization techniques, knowledge on human embryo development has considerably progressed. The purpose of this review is to provide an update on culture conditions allowing an optimal embryo development. During its development, there is a shift in nutritional requirements, in parallel with the availability of nutrients in the female genital tract and the metabolic changes that the embryo undergoes. The main metabolic transition is energy production from pyruvate uptake at cleavage-stage, followed by preferential glucose uptake from compaction. Therefore, culture media used in vitro, whether sequential or one-step, must contain all the elements necessary to get as close as possible to the micro-environment in vivo (carbohydrates, lipids, amino-acids, macromolecules). Morevover, physicochemical culture conditions (oxygen tension, temperature, pH) are variables described as having a significant impact on embryo development. Finally, other parameters such as coculture, dynamic or group embryo culture, although more controversial or difficult to implement, could allow development even closer to physiology. [ABSTRACT FROM AUTHOR]