Rosette-like Structure Research Articles

Morphological and histochemical characteristics of the foregut, midgut, and hindgut, and their alterations during ovarian development in female freshwater prawn, Macrobrachium rosenbergii.

The anatomical, histological, and histochemical characteristics of the foregut (FG), midgut (MG), and hindgut (HG), as well as their alterations during the ovarian cycle in female prawns, Macrobrachium rosenbergii, were investigated. The esophagus (ESO), cardia (CD), and pylorus (PY) are the main components of the FG. An epithelium (Ep) with thick cuticle (Cu) layers lining the ESO, and the ESO is encircled by the ESO glands. The CD has a thick musculature, whereas the Ep of the PY are characterized by numerous villi andcolumnar Ep cells with a thinner layer of Cu. The inner longitudinal (LM)and the outer circular (CM)muscles were both present in the PY. The MG is lined by Ep cells which are connected to the basement membrane, and it lacks Cu. Microvilli, and subapical vacuoles are visible on the apical surface of Ep cells of the MG. The outermost layer is characterized by a dense stripof elastic fibers and a cluster of collagen fibers. The HG has the Ep cells with a thin Cu layer, and the HG glands form a rosette-like structure. The HG is surrounded by the CM and the LM fibers. The reactivities of Periodic Acid Schiff and Alcian Blue in these digestive organs altered throughout the ovarian cycle, and this was supported by the increased expression of mucin levels as ovarian maturation progressed. Our results offer novel and significant insights into the anatomical and histochemical structures of these digestive organs, and demonstrate a significant correlationbetween ovarian development and feeding in the female prawn, M. rosenbergii.

Abstract P103: Assessment of Angiotensin II-induced Calcium Signals in Primary Human Adrenocortical Cells

Background: Cytosolic and mitochondrial Ca 2+ concentrations are key signals for triggering the secretion of aldosterone in primary aldosteronism (PA), the most common form of secondary hypertension. Aim: To investigate [Ca 2+ ] i transients and oscillations in human CD56 + cells isolated from aldosterone producing adenoma (APA) and normal surrounding adrenocortical (AAC) cells. Methods: We assessed [Ca 2+ ] i in CD56 + APA and APA-adjacent cells (AAC) in basal conditions and after angiotensin II (Ang II) stimulation using Fura-2 dye, live confocal microscopy, and an ad hoc developed custom-made pipeline to analyze [Ca 2+ ] i signals in terms of frequency and peak parameters as amplitude, full width at half maximum (FWHM) and area under the curve (AUC). As the two-pore domain K + TASK- 2 channels are under expressed in APA, we used quinidine (20 μM), 20’ prior to [Ca 2+ ] i imaging acquisition to examine the effect of the pharmacological inhibition of this channel. Results: Resting [Ca 2+ ] i basal levels were higher in AAC (n=11) (0.75, IQR;0.90-0.56) than in APA (n=11) (0.36 IQR;0.69-0.33), (p < 0.02). We detected spontaneous Ca 2+ activity, during resting conditions, in both cell types without significant difference in peak parameters. Upon 1 nM Ang II simulation, AAC showed elevated FWHM, amplitude, and AUC peak parameters of first Ca 2+ transients. However, APA cells exhibited elevated peak parameters of subsequent Ca 2+ oscillations. Ca 2 oscillations frequency and degree of oscillating cells were significantly higher in APA cells than in AAC. After 24 hours in culture, both AAC and APA cells developed rosette-like cell structure resembling the “glomeruli” of the intact zona glomerulosa clusters. Functional Statistics and clustering analysis showed synchronous behavior of cells belonging to the same cluster without significant differences between AAC and APA. In AAC, Task-2 Inhibition with quinidine tended to increase spontaneous activity and altered peak’s parameters but did not influence frequency of oscillation. Conclusion: Quantitative assessment of [Ca 2+ ] i signals unveiled significant differences in [Ca 2+ ] i dynamics between human AAC and APA cells. These results suggest the concurrent modulation of frequency and amplitude of [Ca 2+ ] I subsequent oscillations as a potential driver of increased rate of aldosterone production.

11.7T Diffusion Magnetic Resonance Imaging and Tractography to Probe Human Brain Organoid Microstructure

BackgroundHuman brain organoids are 3-dimensional cellular models that mimic architectural features of a developing brain. Generated from human induced pluripotent stem cells, these organoids offer an unparalleled physiologically relevant in vitro system for disease modeling and drug screening. In the current study, we sought to establish a foundation for a magnetic resonance imaging (MRI)–based, label-free imaging system that offers high-resolution capabilities for deep tissue imaging of whole organoids. MethodsAn 11.7T Bruker/89 mm microimaging system was used to collect high-resolution multishell 3-dimensional diffusion images of 2 induced pluripotent stem cell–derived human hippocampal brain organoids. The MRI features identified in the study were interpreted on the basis of similarities with immunofluorescence microscopy. ResultsMRI microscopy at ≤40 μm isotropic resolution provided a 3-dimensional view of organoid microstructure. T2-weighted contrast showed a rosette-like internal structure and a protruding spherical structure that correlated with immunofluorescence staining for the choroid plexus. Diffusion tractography methods can be used to model tissue microstructural features and possibly map neuronal organization. This approach complements traditional immunohistochemistry imaging methods without the need for tissue clearing. ConclusionsThis proof-of-concept study shows, for the first time, the application of high-resolution diffusion MRI microscopy to image 2-mm diameter spherical human brain organoids. Application of ultrahigh-field MRI and diffusion tractography is a powerful modality for whole organoid imaging and has the potential to make a significant impact for probing microstructural changes in brain organoids used to model psychiatric disorders, neurodegenerative diseases, and viral infections of the human brain, as well as for assessing neurotoxicity in drug screening.

Effect of Short Heat Treatments on the Microstructural Evolution and Hardness of Thixoformed Graphene Reinforced Aluminium Composites

Aluminium metal matrix composites are increasingly being used in numerous industries due to their lightweight nature and high strength. The incorporation of graphene into aluminium metal matrix composites has garnered significant interest owing to graphene's capacity to enhance numerous properties concurrently. Hence, this study aimed to fabricate a 0.3 wt.% graphene nanoplatelets reinforced A356 alloy (GNP-A356) composite through stir casting followed by thixoforming and short T6 heat treatment processes. It also evaluated the microstructure and mechanical properties of GNP-A356 after the thixoforming process and short T6 heat treatment. The microstructure of alloy and composite was confirmed by optical microstructure, field emission scanning electron microscopy images, and X-ray diffraction. Microstructure investigations demonstrate the impact of the stirring process on the structural transformation of the 𝛼-Al phase from the dendritic into a rosette-like and globular-like structure. The result also indicated that there was a transformation of eutectic silicon from the shape of a needle-like to spheroid structure after a short heat treatment, showing the efficiency of T6 heat treatment with a shorter time of solution treatment and ageing. Moreover, the increase in relative density and addition of reinforcement led to a significant increment in hardness. The result shows the hardness improved by 35.77% and 77.8% for as-cast and heat-treated composites, respectively, compared to A356 alloy.

Distribution of Bamboo Witches’ Broom Disease in Various Bamboo Species in the Philippines and Molecular Identification of 'Candidatus Phytoplasma luffae'-related Strain 16SrVIII

Bamboo is used for making structures, furniture, handicrafts, and ropes, as well as a source of food in the Philippines. One of the emerging diseases of bamboo in the country is the bamboo witches’ broom (BWB), which has been occasionally noted in three genera of bamboo – including Dendrocalamus, Gigantochloa, and Schizostachyum from various provinces in the Philippines (Ilocos Norte, Laguna, Batangas, Quezon, Agusan del Sur, Bukidnon, and South Cotabato) since the 1990s. However, studies and information about BWB in the country remain lacking and largely unexplored. In this study, we report a similar disease affecting Dendrocalamus and Gigantochloa bamboo species from Bohol and Davao and – for the first time – in Dendrocalamus merrillianus ("bayog") and Bambusa spinosa ("kawayan-tinik") from Isabela and Nueva Vizcaya. As a result of the surveys conducted from 1999–2019, the disease is now identified in six species across four genera of bamboo – namely, Gigantochloa spp. (G. levis and G. atter), Dendrocalamus spp. (D. asper and D. merrillianus), Schizostachyum lumampao, and Bambusa spinosa recorded in 11 provinces in the Philippines. The BWB symptoms include clustering of leaves forming a rosette-like structure, leaf proliferation, excessive limb formation from a single node, and shortening of internodes. Nested PCR using the universal primers P1/P7 and R16MF2/R1 targeting the phytoplasma 16S ribosomal RNA gene revealed positive amplification in five symptomatic BWB samples from Isabela, Philippines. Subsequent sequencing (~ 1.3kbp) and phylogenetic analysis using the representative BWB isolates from Isabela revealed > 98.65% genetic similarity and clustering to Candidatus Phytoplasma luffae, which belongs to the 16SrVIII group (Loofah Witches’ Broom Group). This paper determined the distribution of BWB in different species of bamboo in the Philippines, as well as the association of 'Ca. Phytoplasma luffae'-related strain (16SrVIII) to BWB.

Amniogenesis in Human Amniotic Sac Embryoids after Exposures to Organophosphate Flame Retardants.

Amniogenesis is a key event in biochemical pregnancy, and its failure may result in human embryonic death. However, whether and how environmental chemicals affect amniogenesis remain largely unknown. The objective of the present study was to screen chemicals that may disrupt amniogenesis in an amniotic sac embryoid model and to investigate the potential mechanism of amniogenesis failure, with a focus on organophosphate flame retardants (OPFRs). This study developed a high-throughput toxicity screening assay based on transcriptional activity of octamer-binding transcription factor 4 (Oct4). For the two positive OPFR hits with the strongest inhibitory activity, we used time-lapse and phase-contrast imaging to assess their effects on amniogenesis. Associated pathways were explored by RNA-sequencing and western blotting, and potential binding target protein was identified through a competitive binding experiment. Eight positive hits exhibiting Oct4 expression were identified, with 2-ethylhexyl-diphenyl phosphate (EHDPP) and isodecyl diphenyl phosphate (IDDPP) showing the strongest inhibitory activity. EHDPP and IDDPP were found to disrupt the rosette-like structure of the amniotic sac or inhibit its development. Functional markers of squamous amniotic ectoderm and inner cell mass were also found disrupted in the EHDPP- and IDDPP-exposed embryoids. Mechanistically, embryoids exposed to each chemical exhibited abnormal accumulation of phosphorylated nonmuscle myosin (p-MLC-II) and were able to bind to integrin (). The amniotic sac embryoid models suggested that OPFRs disrupted amniogenesis likely by inhibiting the pathway, thus providing direct in vitro evidence associating OPFRs with biochemical miscarriage. https://doi.org/10.1289/EHP11958.

Одержання виливків із доевтектичних силумінів способом тиксолиття

Experimental studies of the method of thixocasting of AK7ч hypoeutectic silumin using cylindrical billets with different initial prepared structure (dendritic and non-dendritic – rosette-like and globular) of the primary solid phase were carried out. It is shown that after casting using billets with the initial dendritic structure of aluminum solid solution, the structure in shaped castings remains dendritic. At the same time, a certain number of destroyed dendrites are observed in the structure, predominantly melted. The thixocasting of the hypoeutectic silumin AK7ч using billets with the initial rosette-like structure of primary aluminum crystals ensures the production of shaped castings with a globular structure of the primary phase with a globular size of 80–100 μm. At the same time resulting the globular structure of the primary solid phase in castings is homogeneous and evenly distributed over the entire cross section. Thixocasting of silumin AK7ч using billets with the initial globular structure of the primary solid phase does not lead to a change of the structure of the casting. This slightly increases the size of the globules in the casting. Eutectic colonies in shaped castings obtained by thixocasting are characterized by a higher degree of differentiation compared to the initial structures of billets. Determination of mechanical properties showed an increased plasticity of the investigated hypoeutectic silumin in castings obtained after thixocasting without additional hardening heat treatment. Keywords: thixocasting, hypoeutectic silumin, non-dendritic structure, globular structure, rosette-like structure, solid-liquid billet, shaped casting.

Rosette-like Structure: A Main Dermoscopic Feature in a Small Trichilemmal Cyst.

Citation: Bazzacco G, Zelin E, Maronese CA, et al. Rosette-like structure: a main dermoscopic feature in a small trichilemmal cyst. Dermatol Pract Concept. 2022;12(1):e2022021. DOI: https://doi.org/10.5826/dpc.1201a21

Ag3VO4 anchored ZnTi hydrotalcite microspheres with rosette-like structure for tetracycline degradation

The Ag3VO4/ZnTi-LDH (Ag3VO4/LDH) with 3D rosette-like structure were designed and prepared by anchoring Ag3VO4 nanoparticles on the ZnTi-LDH. The as-prepared materials were characterized by various techniques, and their photocatalytic performances for the tetracycline (TC) degradation were also investigated under simulated solar light irradiation. It was found that the Ag3VO4 nanoparticles grew on the surface of the LDH host layers, and the photocatalytic performances depended on the loading amount of the Ag3VO4 nanoparticles. The 15%Ag3VO4/LDH had uniformly distributed Ag3VO4 nanoparticles and the largest specific surface area (SBET), which increased surficial active sites to improve the photocatalytic activity. The 15%Ag3VO4/LDH exhibited an excellent photocatalytic activity with TC removal rate of 83.1%, which was about 6.3 and 6.8 times higher than those of the Ag3VO4 and ZnTi-LDH, respectively. Especially for the spent 15%Ag3VO4/LDH, the TC removal rate at the 5th cycle still kept around 95% at first cycle, and there was little change in morphological structure and surface chemical property, suggesting that the excellent structure and photocatalytic stabilities. At the same time, the probable photocatalytic mechanism was put forward, and the likely TC degradation pathway was also proposed on the basis of the intermediate products detected by GC–MS technique.

Hierarchical Core-Shell Structure of 2D VS2@VC@N-Doped Carbon Sheets Decorated by Ultrafine Pd Nanoparticles: Assembled in a 3D Rosette-like Array on Carbon Fiber Microelectrode for Electrochemical Sensing.

The development of two-dimensional (2D) nanohybrid materials with heterogeneous components in nanoscale and three-dimensional (3D) well-ordered assembly in microscale has been regarded as an effective way to improve their overall performances by the synergistic coupling of the optimized structure and composition. In this work, we reported the design and synthesis of a new type of hierarchically core-shell structure of 2D VS2@VC@N-doped carbon (NC) sheets decorated by ultrafine Pd nanoparticles (PdNPs), which were vertically grown on carbon fiber (CF) and assembled into a unique 3D rosette-like array. The resultant VS2@VC@NC-PdNPs modified CF microelectrode integrated the structural and electrochemical properties of the heterogeneous hybridization of core-shell VS2@VC@NC-PdNPs sheets with a unique rosette-like array structure, and gave rise to a significant improvement in terms of electron transfer ability, electrocatalytic activity, stability, and biocompatibility. Under the optimized conditions, the VS2@VC@NC-PdNPs modified CF microelectrode demonstrated excellent electrochemical sensing performance towards biomarker hydrogen peroxide (H2O2) including a high sensitivity of 152.7 μA cm-2 mM-1, a low detection limit of 50 nM (a signal-to-noise ratio of 3:1), as well as good reproducibility and anti-interference ability, which could be used for the real-time in situ electrochemical detection of H2O2 in live cancer cells and cancer tissue. The remarkable performances of the proposed nanohybrid microelectrode will have a profound impact on the design of diverse 2D layered materials as a promising candidate for electrochemical biosensing applications.

In-situ growth of 3D rosette-like copper nanoparticles on carbon cloth for enhanced sensing of ammonia based on copper electrodissolution

Copper is an attractive candidate for sensing ammonia. Here, an electrodissolution mechanism for measuring liquid-phase ammonia was developed via a novel three-dimensional rosette-like structure of copper nanoparticles (CuNPs) integrated onto carbon cloth (CuNPs/CC). A one-step hydrothermal synthetic procedure was employed to construct the metallic CuNPs with a stereo rosette-like pattern on flexible CC substrate. The morphology, composition and sensing performance of the as-prepared composite were characterised in detail. The CuNPs/CC composite showed excellent sensing performance to ammonia, which is attributed to the electrodissolution of CuNPs being promoted by ammonia to form a stabilised copper-ammonia complex. This electrochemical response occurs without the electro-oxidation of ammonia, thus avoiding the energy barrier of the N–N bond and the toxicity of N-adsorbates, which is advantageous for ammonia detection. In addition, the sensor also shows very high sensitivity to ammonia with a low detection limit, as well as good anti-interference performance, repeatability and stability. The high accuracy and precision for the quantification of ammonia concentration in a variety of real samples indicate that the CuNPs/CC composition has potential in the development of high-performance ammonia sensors.

Inhibition of AMD-Like Pathology With a Neurotrophic Compound in Aged Rats and 3xTg-AD Mice.

Age-associated macular degeneration (AMD), which leads to loss of vision at its end stage, is one of the most common neurodegenerative diseases among the elderly. However, to date, no effective drug therapy is available for the prevention of AMD. Here, we report the occurrence of AMD pathology and its prevention by chronic treatment with the neurotrophic peptidergic compound P021, in aged rats and 3xTg-AD mice. We found photoreceptor degeneration, lipofuscin granules, vacuoles, and atrophy in retinal pigment epithelium (RPE) as well as Bruch’s membrane (BM) thickening; in aged rats, we even found rosette-like structure formation. Microgliosis and astrogliosis were observed in different retinal layers. In addition, we also found that total tau, phosphorylated tau, Aβ/APP, and VEGF were widely distributed in the sub-retina of aged rats and 3xTg mice. Importantly, chronic treatment with P021 for 3 months in rats and for 18 months in 3xTg mice ameliorated the pathological changes above. These findings indicate the therapeutic potential of P021 for prevention and treatment of AMD and retinal changes associated with aging and Alzheimer’s disease.

Microstructure evolution of A380 aluminum alloy during rheological process under applied pressure

In squeeze casting process, the essence of mold-filling and feeding is rheological solidification of the alloy melt under pressure. Microstructure evolution is inevitable in this process, which affects the mold-filling and feeding in turn. In this work, the Archimedes spiral sample prepared by indirect squeeze casting was applied to investigate the microstructure evolution during the rheological process under pressure. The results showed that the primary α-Al phase was transformed from fine rosette-like or granular structure to coarse platelet-like structure with the increase of spiral length. However, the primary α-Al grain size of the starting point had a slight growing trend compared with that at the position of 140 mm away from the starting point. The volume fraction of the primary α-Al phase increased from 45.57% to 70.35% along the spiral length direction, demonstrating that the experimental pressure improved the rheological ability of the alloy melt to some extent. Furthermore, the eutectic Si phase was varied from a fine granular or wormlike structure to a coarse platelet-like or needle-like structure, and the dispersion of eutectic Si particles was also varied along the spiral length direction. This microstructure evolution was mainly owing to the comprehensive action of rheological solidification and pressurized solidification. More specifically, the microstructure evolution strongly depended on the pressure and rheological velocity during the rheological process, however, the effect of rheological distance was relatively small.

CENP-A nucleosome clusters form rosette-like structures around HJURP during G1

CENP-A is an essential histone H3 variant that epigenetically marks the centromeric region of chromosomes. Here we show that CENP-A nucleosomes form characteristic clusters during the G1 phase of the cell cycle. 2D and 3D super-resolution microscopy and segmentation analysis reveal that these clusters encompass a globular rosette-like structure, which evolves into a more compact structure in late G1. The rosette-like clusters contain numerous CENP-A molecules and form a large cellular structure of ∼250–300 nm diameter with remarkably similar shapes for each centromere. Co-localization analysis shows that HJURP, the CENP-A chaperone, is located in the center of the rosette and serves as a nucleation point. The discovery of an HJURP-mediated CENP-A nucleation in human cells and its structural description provide important insights into the mechanism of CENP-A deposition and the organization of CENP-A chromatin in the centromeric region.

Morphological transformation of electrodeposited Pt and its electrocatalytic activity towards direct formic acid fuel cells

Engineering the shape and size of platinum catalysts is crucial in determining fuel cell performance. In this study, Pt electrodeposited on carbon black-coated carbon paper at three different potentials (viz. 0.2, 0, and −0.2 vs. SHE) was evaluated for its performance in direct formic acid fuel cells (DFAFCs). The electrodeposited catalysts were analysed using SEM, XRD, and electrochemical techniques. The shape of the electrodeposited Pt transformed from globular (0.2 V) to dendritic (0 V) and to rosette-like (−0.2 V) structure by increasing the deposition potential in the cathodic direction. The change in shape could be due to the variation in the accompanying hydrogen evolution with the deposition potential in acidic electrolyte. The dendritic structure of Pt deposited at 0 V showed a higher electrochemical surface area and enhanced catalytic activity towards formic acid oxidation than the other two shapes. To study the performance of electrocatalysts in DFAFC, the anode catalyst was prepared in a new approach of layer-by-layer electrodeposition on carbon to maximize the triple phase boundary. The layered dendritic Pt generated a maximum power density of 42 mW cm−2, comparable with the commercial Pt/C catalyst (46 mW cm−2) at 70 °C for 3 M formic acid.

Hydration effect on proton transfer in melamine-cyanuric acid complex.

Self-assembly of melamine-cyanuric acid (MC) leads to urinary tract calculi and renal failure. The hydration effects on molecular geometry, the IR spectra, the frontier molecular orbital, the energy barrier of proton transfer (PT), as well as the stability of MC were explored by density functional theory (DFT) calculations. The intramolecular PT breaks the big π-conjugated ring of melamine or converts the p-π conjugation (:N-C'=O) to π-π conjugation (O=C-N=C') of cyanuric acid. The intermolecular PT varies the coupling between melamine and cyanuric acid from pure hydrogen bonds (Na…HNd and NH…O) to the cooperation of cation…anion electrostatic interaction (NaH(+)…Nd (-)) and two NH…O hydrogen bonds. Distinct IR spectra shifts occur for Na…HNd stretching mode upon PT, i.e., blue-shift upon intramolecular PT and red-shift upon intermolecular PT. It is expected that the PT would inhibit the generation of rosette-like structure or one-dimensional tape conformer for the MC complexes. Hydration obviously effects the local geometric structure around the water binding site, as well as the IR spectra of NH…O and N…HN hydrogen bonds. Hydration decreases the intramolecular PT barrier from ~45 kcal mol(-1) in anhydrous complex to ~11.5 kcal mol(-1) in trihydrated clusters. While, the hydration effects on intermolecular PT barrier is slight. The relative stability of MC varies slightly by hydration due to the strong hydrogen bond interaction between melamine and cyanuric acid fragments. Graphical Abstract Hydration effect on proton transfer in melamine-cyanuric acid complex.

Chiral Transition of the Supramolecular Assembly by Concentration Modulation at the Liquid/Solid Interface

Global hetero- and homochiral polymorphous assemblies from an achiral fluorenone derivative were successfully constructed with multiple intermolecular hydrogen bonds by concentration modulation. Scanning tunneling microscopy investigations reveal that a heterochiral supramolecular double rosette-like structure was fabricated for the first time via hydrogen bond interactions with achiral 1-octanoic acid under low concentrations. When the solution concentration was increased, the structural transition from a heterochiral double rosette-like structure to a homochiral windmill-like pattern was observed. Interestingly, these two metastable structures ultimately could transform into a stable zigzag pattern at a bias voltage prompted by the STM tip. At high concentrations, only an achiral octamer arrangement could be obtained, owing to the changes of intermolecular hydrogen bonding, van der Waals force, and dipole–dipole interactions. The present results provided an important impetus for the induction and contro...

Spinal Intramedullary Metastatic Small Cell Lung Cancer Mimicking Ependymoma on Frozen Biopsy During Surgery

A 70-year-old man presented with a 2-month history of progressive weakness of his arm and leg. During surgery, a frozen biopsy revealed an ill-defined rosette-like structure, mitosis, and hypervascularity. A diagnosis of ependymoma was made and a gross total resection was performed. However, the result of the definitive biopsy was not ependymoma, but small cell lung cancer. This report highlights the need for a close clinicopathologic correlation to enable the correct intraoperative frozen section diagnosis of spinal tumors, including a careful examination of the histologic features and operative and radiologic tumor findings.

Cell death and morphogenesis during early mouse development: are they interconnected?

Shortly after implantation the embryonic lineage transforms from a coherent ball of cells into polarized cup shaped epithelium. Recently we elucidated a previously unknown apoptosis-independent morphogenic event that reorganizes the pluripotent lineage. Polarization cues from the surrounding basement membrane rearrange the epiblast into a polarized rosette-like structure, where subsequently a central lumen is established. Thus, we provided a new model revising the current concept of apoptosis-dependent epiblast morphogenesis. Cell death however has to be tightly regulated during embryogenesis to ensure developmental success. Here, we follow the stages of early mouse development and take a glimpse at the critical signaling and morphogenic events that determine cells destiny and reshape the embryonic lineage.

Developmental plasticity, cell fate specification and morphogenesis in the early mouse embryo.

A critical point in mammalian development is when the early embryo implants into its mother's uterus. This event has historically been difficult to study due to the fact that it occurs within the maternal tissue and therefore is hidden from view. In this review, we discuss how the mouse embryo is prepared for implantation and the molecular mechanisms involved in directing and coordinating this crucial event. Prior to implantation, the cells of the embryo are specified as precursors of future embryonic and extra-embryonic lineages. These preimplantation cell fate decisions rely on a combination of factors including cell polarity, position and cell–cell signalling and are influenced by the heterogeneity between early embryo cells. At the point of implantation, signalling events between the embryo and mother, and between the embryonic and extraembryonic compartments of the embryo itself, orchestrate a total reorganization of the embryo, coupled with a burst of cell proliferation. New developments in embryo culture and imaging techniques have recently revealed the growth and morphogenesis of the embryo at the time of implantation, leading to a new model for the blastocyst to egg cylinder transition. In this model, pluripotent cells that will give rise to the fetus self-organize into a polarized three-dimensional rosette-like structure that initiates egg cylinder formation.