Developmental Dynamics[JOURNAL]
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200 papers
Multi-stage transcriptome analysis reveals genetic orchestration of rat testis development.
Chan CC, Jamalpour S, Samudi C … +2 more , Omar H, Bhassu S
Dev Dyn · 2026 Jul · PMID 42383567 · Publisher ↗
BACKGROUND: Testicular development is a highly orchestrated process essential for male fertility, but its temporal genetic regulation remains incompletely resolved in many mammalian models. This study re-analyses rat tes...
BACKGROUND: Testicular development is a highly orchestrated process essential for male fertility, but its temporal genetic regulation remains incompletely resolved in many mammalian models. This study re-analyses rat testis transcriptomes across 15 stages from embryonic day 12 to postnatal week 16 using bulk RNA-sequencing data from a multispecies organ development atlas, generating a continuous, testis-focused temporal framework, and pinpointing key developmental transition windows and regulatory modules. RESULTS: Of 23,748 annotated genes, 17,717 were differentially expressed (DEGs), and hierarchical plus co-expression analyses identified four principal expression modules and five clusters capturing spermatogenic, morphogenetic, immune, and neurone-like programs. Four major transcriptional transition windows, embryonic day 14, embryonic day 19, postnatal week 2, and postnatal week 6, were defined, with the largest remodeling between 2 and 6 weeks coinciding with the onset of robust spermatogenesis and marking a particularly vulnerable window for environmental or toxicant-induced perturbation. Stage-specific spermatogenesis-associated gene sets at embryonic day 19 (n = 28), postnatal week 2 (n = 61), and week 6 (n = 735) showed minimal overlap, supporting sequential regulatory waves driving germ cell commitment, early meiosis, and terminal differentiation. Target enrichment analyses highlighted five conserved microRNAs (rno-miR-151-5p, rno-miR-29b-3p, rno-miR-384-5p, rno-miR-500-5p, rno-miR-672-5p) whose predicted and validated targets form modules related to extracellular matrix remodeling, apoptosis and cell-cycle control, ion-channel signaling, and neuronal-like pathways, with high sequence conservation to human homologs. Immune-related genes and blood-testis barrier components displayed coordinated expression dynamics, and a conserved core of 487 spermatogenesis genes showed strong cross-mammalian orthology, indicating a deeply shared transcriptional backbone on which species-specific regulatory nuances are layered. CONCLUSIONS: This multistage transcriptomic analysis delineates major developmental transitions, co-expression modules, and regulatory miRNA-mRNA networks that orchestrate rat testis maturation and highlight a critical P2W-P6W transition window. The resource complements existing multiorgan and single-cell datasets by providing a testis-focused temporal framework and identifies conserved gene sets and regulatory candidates of direct relevance to male infertility, toxicology, and cross-species translational studies.
Three-dimensional observation of the muscle-tendon integration process in mouse embryos.
Sagasaki R, Taniguchi A, Oka S … +8 more , Mishima M, Yamasaki Y, Kawa Y, Schlesinger S, Fujita R, Shukunami C, Asahara H, Inui M
Dev Dyn · 2026 Jul · PMID 42383507 · Publisher ↗
BACKGROUND: Muscle-tendon integration is a crucial step in the morphogenesis of the vertebrate locomotion system. As the limb muscle and tendon progenitor cells derive from distinct embryonic origin, their integration re...
BACKGROUND: Muscle-tendon integration is a crucial step in the morphogenesis of the vertebrate locomotion system. As the limb muscle and tendon progenitor cells derive from distinct embryonic origin, their integration requires precise mutual positioning. This process has been described mainly by tissue sectioning and in situ hybridization, which are not well suited for understanding the three-dimensional (3D) organization. To address these limitations, this study applied tissue clearing and light-sheet microscopy to visualize the muscle-tendon integration process in 3D in mouse embryonic limbs. RESULTS: By combining CUBIC reagents, immunofluorescence, and fluorescent reporter mice, we were able to resolve the 3D arrangement of forelimb muscles and tendons in mouse embryos from E11.5 to E15.0. Interestingly, we found that a subpopulation of Scleraxis+ tendon lineage cells remains within the interstitial space of myofibers even after muscle-tendon integration is established, implying the existence of previously undescribed cellular heterogeneity within the Scleraxis+ cell population at this stage. Moreover, our approach successfully captured the muscle-tendon morphologies altered by genetic perturbations, such as Scleraxis-lineage ablation and Myomaker knockout. CONCLUSIONS: In summary, this tissue clearing and light-sheet microscopy approach provides a versatile method for analyzing dynamically changing embryonic muscle-tendon morphologies and will facilitate deeper understanding of the muscle-tendon integration process.
Goofy/123Cre lineage tracing differentiates olfactory and vomeronasal neurons from GnRH-1 and terminal nerve neurons during neuronal migration and reveals additional olfactory placode-derived cells in the brain.
Amato E, Call MV, LeFever NM … +3 more , Aviles-Carlos M, Dolphin NM, Forni PE
Dev Dyn · 2026 Jun · PMID 42294802 · Publisher ↗
The olfactory placode (OP) generates a broad array of chemosensory neurons in the nasal region, including olfactory sensory neurons, vomeronasal sensory neurons, neurons of the septal organ, and Grueneberg ganglion. Duri...
The olfactory placode (OP) generates a broad array of chemosensory neurons in the nasal region, including olfactory sensory neurons, vomeronasal sensory neurons, neurons of the septal organ, and Grueneberg ganglion. During invagination, the OP also generates migratory neuronal populations, including gonadotropin-releasing hormone-1 (GnRH-1) neurons, somatostatin-expressing neurons, and Prokineticin Receptor 2 (Prokr2) pioneer/terminal nerve (TN) neurons. Despite extensive research, the genetic lineage and molecular identity of many OP-derived neurons remain unclear. GnRH-1 neurons are vital for reproductive functions and chemosensory processing but are genetically distinct from olfactory and vomeronasal sensory neurons. The regulator Goofy/Gfy is expressed in placode-derived chemosensory neurons. Our study aimed to determine whether its expression is restricted to these neurons or shared among OP derivatives. The 123Cre mouse expresses Cre under the Gfy1 promoter. Cre tracing analyses across embryonic stages showed widespread 123Cre recombination in chemosensory neurons but not in migrating GnRH-1. However, at late development and postnatal stages, some Gfy-traced cells appear in the basal forebrain, including a subset of GnRH-positive neurons. These findings demonstrate heterogeneity among migratory nasal neurons and suggest that, besides GnRH-1, other nasal-origin neurons also populate the forebrain. Postnatal studies of vomeronasal neurons revealed distinct developmental trajectories for the two main VSN subtypes.
Prenatal sexual dimorphism in human pelvic tilt at the onset of fetal ossification.
Kanahashi T, Matsubayashi J, Imai H … +3 more , Yamada S, Otani H, Takakuwa T
Dev Dyn · 2026 Jun · PMID 42289843 · Publisher ↗
BACKGROUND: Sexual dimorphism in pelvic morphology has been confirmed at the onset of primary ossification. Since pelvic tilt influences spinal alignment and bipedal locomotion, determining the initial emergence of sex-s...
BACKGROUND: Sexual dimorphism in pelvic morphology has been confirmed at the onset of primary ossification. Since pelvic tilt influences spinal alignment and bipedal locomotion, determining the initial emergence of sex-specific tilt differences is crucial. Herein, we measured pelvic tilt and lumbosacral inclination angles (LSIAs) using magnetic resonance imaging in 72 human fetuses (crown-rump length [CRL], 50-225 mm; 34 males [M] and 38 females [F]). RESULTS: The cranial-caudal axis was defined from the first to third sacral vertebrae, and sex differences were assessed using multiple regression analysis including sex, CRL subgroup, and their interaction. Females exhibited greater posterior iliac tilt than males (anterior superior iliac spine-posterior superior iliac spine line: least-squares mean; [F] -19.6° vs. [M] -17.0°; p = .038). The LSIA (L1/S5-sacral promontory) was larger in males ([F] 166.3° vs. [M] 170.2°; p = .033), indicating more dorsally positioned sacra in females. Principal component analysis identified two major components representing os coxae rotation and sacral inclination to the lumbar spine, indicating independent developmental patterns. CONCLUSIONS: The findings demonstrate that pelvic sexual dimorphism includes tilt orientation from the onset of ossification, reflecting sex-specific developmental trajectories during the prenatal period.
Meet the editorial team. An interview with Ralph Marcucio, Assistant Editor, University of California San Francisco, United States.
Trevorrow P, Marcucio R
Dev Dyn · 2026 Jun · PMID 42281166 · Publisher ↗
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Editorial highlights.
Trainor PA
Dev Dyn · 2026 Jun · PMID 42281157 · Publisher ↗
Abstract loading — click title to view on PubMed.
Pulmonary development in Squamata: Insights from embryonic studies using micro-CT.
Champini BG, Diaz RE, Schachner ER … +1 more , Klein W
Dev Dyn · 2026 Jun · PMID 42281155 · Full text
BACKGROUND: Pulmonary development in tetrapods is a complex process, especially within squamates, where single-chambered, transitional, and multi-chambered lungs can be found in adult animals. While the embryological dev...
BACKGROUND: Pulmonary development in tetrapods is a complex process, especially within squamates, where single-chambered, transitional, and multi-chambered lungs can be found in adult animals. While the embryological development of the respiratory system of lizards and snakes was studied in a number of species between the 1830s and 1940s, the subject has only received sporadic attention since then. With the advancement of imaging technology, non-invasive methods can be used to explore the degree of respiratory system development in embryos of different ages. RESULTS: Micro-computed tomography (micro-CT) was used to reconstruct three-dimensional extrapulmonary airways and pulmonary structures and to analyze lung development in five species of lizards (two species of Teiidae, one Anguidae, one Iguanidae, and one Tropiduridae) and one species of snake (Lamprophiidae). Results indicate that pulmonary parenchyma development was undetectable in the earliest embryonic stages, likely due to technical or developmental limitations. In later stages, structures such as faveolar parenchyma and intrapulmonary subdivisions were clearly observable, resembling the morphology seen in adult animals. CONCLUSIONS: These findings provide valuable insights into the viability of micro-CT scans to investigate embryonic respiratory systems, as well as into the evolution and development of the respiratory system in Squamata.
Application of centromeric fluorescence in situ hybridization probes for embryological and cell studies-A practical approach to validate chromosome stability in Bovinae.
Madeja ZE, Szczerbal I, Osyra MH … +2 more , Ziętek MM, Bernat A
Dev Dyn · 2026 Jun · PMID 42261994 · Publisher ↗
BACKGROUND: Advances in reproductive and cellular biotechnology have significantly enhanced the ability to study, conserve, and manipulate species within the Bovinae family, including domestic cattle and the endangered E...
BACKGROUND: Advances in reproductive and cellular biotechnology have significantly enhanced the ability to study, conserve, and manipulate species within the Bovinae family, including domestic cattle and the endangered European bison (wisent). Central to the success of such technologies, including in vitro fertilization, somatic cell nuclear transfer, and the culture of pluripotent stem cells (PSCs), is the chromosome stability of cultured cells and embryos. RESULTS: Here, we present the design and application of a specific centromere Cot-1 DNA probe for fluorescence in situ hybridization (FISH). We demonstrate its utility in assessing chromosomal stability of bovine and wisent somatic cells and in vitro-produced embryos. The probe shows high specificity for Bovinae cells and can be used on both metaphase plates and interphase nuclei, enabling rapid cytogenetic analysis even in slow-dividing or senescent cells. CONCLUSIONS: The newly generated Cot-1 DNA-based FISH probe provides a rapid and reliable method for species-specific cytogenetic monitoring in Bovinae. Furthermore, it allows accurate monitoring of chromosomal stability and quality control in PSC systems reliant on feeder layers and offers a streamlined approach for monitoring embryo chromosomal integrity in vitro. Broader application of this method may improve outcomes in reproductive technologies, conservation programs, and the generation of stable cell lines for biotechnological and agricultural use.
In silico analysis of putative interactions identifies fibroblasts as hubs for cell-cell communication during early regeneration of the zebrafish heart.
Carvalho JAS, Arora P, Marques IJ … +4 more , Galardi-Castilla M, Timmer L, van Rooij E, Mercader N
Dev Dyn · 2026 Jun · PMID 42261968 · Publisher ↗
BACKGROUND: The zebrafish heart regenerates upon injury. During injury response, fibroblasts and endothelial cells accumulate at the site of damage, and cardiomyocyte cell cycle reentry allows cardiac muscle regrowth. It...
BACKGROUND: The zebrafish heart regenerates upon injury. During injury response, fibroblasts and endothelial cells accumulate at the site of damage, and cardiomyocyte cell cycle reentry allows cardiac muscle regrowth. It is relevant to understand how the different cell types communicate with each other to coordinate regeneration. RESULTS: We present an in silico meta-analysis of ligand-receptor (LR) interactions among periostin b fibroblasts, kdlr endothelial cells, sox10-derived and rest of ventricular cardiomyocytes, at 7 days post-injury. Using bulk RNA-seq data sets from fluorophore-activated cell-sorted populations, we selected for differentially expressed genes encoding LR pairs. Human-centric interaction data from the OmniPath database were adapted to zebrafish data through ortholog mapping to reconstruct a comprehensive interactome. We observed that fibroblasts and, to a lesser extent, endothelial cells emerged as signaling hubs, while cardiomyocytes primarily acted as signal recipients. Network analysis, combining PageRank, expression change, and literature-based novelty, revealed both known and novel candidate genes in regeneration, and allowed pathway enrichment analysis. An interactive web tool enables exploration of the ranked interaction data set, providing a systematic resource to guide future functional studies. CONCLUSIONS: This study provides a systematic and unbiased map of regenerative signaling in the zebrafish heart, establishing a resource to guide functional investigations.
Spatial and temporal coordination of signaling pathways in tissue differentiation: Developmental atlas of protein expression during zebra finch beak maturation.
Duckworth RA, Britton SE, Lee CA … +2 more , Chenard KC, Badyaev AV
Dev Dyn · 2026 May · PMID 42219676 · Publisher ↗
BACKGROUND: Morphogenesis depends on spatial and temporal coordination of signaling pathways, yet context-specificity in interactions among these pathways during cartilage and bone differentiation remains poorly understo...
BACKGROUND: Morphogenesis depends on spatial and temporal coordination of signaling pathways, yet context-specificity in interactions among these pathways during cartilage and bone differentiation remains poorly understood. Here we map cellular and histological localization of regulatory proteins forming core craniofacial developmental pathways of the zebra finch (Taeniopygia guttata) to provide insight into their functional roles during beak morphogenesis. RESULTS: We present an atlas of spatiotemporal coexpression of β-catenin, Bmp4, CaM, Dkk3, Fgf8, Ihh, Tgfβ2, and Wnt4 across embryonic stages HH29-42. Early stages (HH29-32), showed broad expression across epithelial and mesenchymal tissues, followed by progressive compartmentalization by HH36, with pronounced divergence among tissues. Notably, at later stages, proteins showed tissue-specific distributions in boundary versus core regions of chondrogenic and osteogenic domains, indicating coordinated cross-pathway patterning during cartilage and bone formation. CONCLUSIONS: We find that osteogenesis in the zebra finch beak is organized by coordinated signaling between boundary-associated cells and differentiating cores; cross-pathway feedback establishes bone and cartilage differentiation while maintaining boundaries. Our results corroborate core aspects of craniofacial signaling dynamics and yet reveal unexpected subcellular localization of some key proteins identifying regulatory complexity not captured by prior transcript-level maps. This atlas provides a protein-level baseline for comparative and mechanistic studies of avian beak morphogenesis.
The hedgehog co-receptors cdon and boc function redundantly to regulate zebrafish craniofacial development.
Nickens R, Guitar S, Zepeda B … +3 more , Roffers-Agarwal J, Artinger KB, Lencer E
Dev Dyn · 2026 May · PMID 42216776 · Publisher ↗
BACKGROUND: Craniofacial development is a complex developmental process that involves formation of the skeleton, muscle, and tendons. Defects in craniofacial development result in common hereditary disorders. Among genet...
BACKGROUND: Craniofacial development is a complex developmental process that involves formation of the skeleton, muscle, and tendons. Defects in craniofacial development result in common hereditary disorders. Among genetic factors regulating craniofacial development, dysregulated hedgehog signaling is associated with craniofacial skeletal defects such as orofacial clefting and holoprosencephaly. Here, we characterize craniofacial phenotypes associated with two hedgehog signaling co-receptors, cdon and boc, in zebrafish. Genetic pedigree analyses have previously linked both cdon and boc to microform holoprosencephaly, and mutations of Cdon and Boc in mouse result in craniofacial phenotypes. However, a detailed analysis of craniofacial phenotypes associated with cdon and boc in zebrafish has not been completed. RESULTS: Our studies show that cdon and boc act redundantly to promote craniofacial cartilage, tendon, and muscle development in zebrafish. Using RNA-seq and HCR in situ hybridization, we show that mutations of cdon and boc result in misregulation of chondrogenesis gene expression including Indian hedgehog ligand, tendon-associated thrombospondin genes, and FOX transcription factors. CONCLUSIONS: Our data are consistent with a model whereby cdon and boc together modify hedgehog activity in the head and establish a foundation for using zebrafish to further understand the role of cdon and boc in craniofacial hereditary disorders such as holoprosencephaly.
Interspecific patterns of variation in dental growth increments of crocodilians.
Hogg R
Dev Dyn · 2026 May · PMID 42216756 · Publisher ↗
BACKGROUND: Multiple studies have supported the hypothesis that incremental growth lines in crocodilian dentin are analogous with circadian von Ebner's lines in mammals; however, variation in these growth lines has been...
BACKGROUND: Multiple studies have supported the hypothesis that incremental growth lines in crocodilian dentin are analogous with circadian von Ebner's lines in mammals; however, variation in these growth lines has been largely unstudied. It is also unknown whether accentuated dentin striations in crocodilians may represent a supradian periodicity analogous to Andresen lines in mammalian dentin. Therefore, the objective of this study is to histologically assess variation in von Ebner's lines and accentuated growth lines among crocodilians. RESULTS: The data do not support the hypothesis that crocodilians express supradian periodicity in accentuated striations of dentin. DSR is significantly correlated with total length and body mass. DSR variance also shows a significant relationship with body size. CONCLUSIONS: Body size seems to be the major factor governing DSR in crocodilians; this relationship is expressed both intra- and interspecifically in this dataset, warranting further study of intraspecific variation to assess the impact of ontogeny on DSR within this group. Accentuated striations may not be useful as markers of periodicity in crocodilians, but may be useful indicators of stress or other physiological events in life history analyses.
Neurotrophin signaling is required for the correct formation of the precerebellar nuclei in mouse embryos.
Okada T, Keino-Masu K, Masu M
Dev Dyn · 2026 May · PMID 42216444 · Publisher ↗
BACKGROUND: In the developing brain, neuronal migration is one of the critical steps in the establishment of an accurate neural network. When neurons reach their final destination, they form layered structures or nuclei....
BACKGROUND: In the developing brain, neuronal migration is one of the critical steps in the establishment of an accurate neural network. When neurons reach their final destination, they form layered structures or nuclei. Precerebellar neurons (PCNs) form several nuclei in the pons and medulla and project mossy and climbing fibers to the cerebellum. PCNs originate from the lower rhombic lip in the dorsal hindbrain and migrate tangentially toward their destinations. When PCNs reach their presumptive nucleus-forming region, they change their migration direction from tangential to radial to form the precerebellar nuclei. Although various molecules have been shown to control PCN migration and nucleogenesis, the mechanisms underlying the development of the precerebellar system remain largely unknown. RESULTS: We investigated the possible roles of two members of the neurotrophin family, brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3), in PCN development in mouse embryos. We found that Bdnf and Ntf3, which encode BDNF and NT-3, respectively, are expressed in their nucleus-forming regions in the pons and medulla, whereas their receptor genes are expressed in migrating PCNs. Disrupting these genes singly or in combination led to abnormal nucleogenesis of PCNs. CONCLUSION: Our findings indicate that neurotrophin signaling is required for accurate formation of the precerebellar nuclei.
Distinction of dental mesenchymal cell populations during molar tooth germ development via analysis of the spatiotemporal expression patterns of mRNAs for Shh ligand receptors Ptch1 and Hip1 using in situ hybridization.
Sunohara M, Morikawa S, Yokoyama M … +5 more , Maeda Y, Nakashima D, Kasamatsu A, Uzawa K, Suzuki K
Dev Dyn · 2026 May · PMID 42204835 · Publisher ↗
BACKGROUND: During early tooth development, cranial neural crest cells migrating to the oral region form dental mesenchyme. To date, the molecular mechanism by which dental mesenchymal cells further migrate and different...
BACKGROUND: During early tooth development, cranial neural crest cells migrating to the oral region form dental mesenchyme. To date, the molecular mechanism by which dental mesenchymal cells further migrate and differentiate into odontoblasts remains largely unknown. We hypothesize that the dental epithelium, being the only source of Shh, a chemotactic peptide, attracts future odontoblasts expressing the Shh receptor Ptch1. RESULTS: Changes in the spatiotemporal distribution of cells expressing Shh, Ptch1, and Hip1 and of nestin protein throughout early tooth development were evaluated via in situ hybridization and immunohistochemistry, respectively. Dental mesenchymal cells were found to be separated into three putative cell population types based on spatiotemporal gene expression patterns: presumptive Ptch1(-)/Hip1(-) non-odontoblastic cells forming the initial dental papilla cell cluster; presumptive Ptch1(+)/Hip1(-) odontoblast lineage cells; and presumptive Ptch1(+)/Hip1(+) cells possibly forming dental follicle and surrounding mesenchyme. Ptch1(+)/Hip1(-) cells seemed to invade the developing dental papilla actively at embryonic day 15.5 (E15.5), resulting in an abundant distribution of the cells by the early bell stage at E16.5. The distribution pattern of presumptive Ptch1(+)/Hip1(-) cells partially overlapped with that of nestin-expressing cells. CONCLUSION: Presumptive Ptch1(+)/Hip1(-) dental mesenchymal cells may migrate to the cusp region of the dental papilla, leading to odontoblast differentiation.
Maternal obesity and offspring neurodevelopment: Mechanisms, risks, and prevention opportunities.
Djamalutdinova I, Turdibekov K, Kholikov A … +2 more , Abdullaev D, Ruziyeva G
Dev Dyn · 2026 May · PMID 42185934 · Publisher ↗
The prevalence of maternal obesity is continuously increasing worldwide, making maternal overweight and obesity one of the most important early life risk factors that can affect the neurodevelopment of offspring. Data fr...
The prevalence of maternal obesity is continuously increasing worldwide, making maternal overweight and obesity one of the most important early life risk factors that can affect the neurodevelopment of offspring. Data from large epidemiological studies indicate that higher prepregnancy BMI, as well as excessive weight gain during pregnancy, are associated with an increased risk of autism spectrum disorder, attention deficit/hyperactivity disorder, internalizing symptoms, cognitive impairment, cerebral palsy, and other neurodevelopmental outcomes. Preclinical studies have also provided a clearer understanding of the biological mechanisms, suggesting that maternal obesity can induce oxidative stress, metabolic inflammation, and placental dysfunction, which impair nutrient and oxygen delivery during critical periods of brain development. Other proposed pathways include activation of microglia and astroglia, dysbiosis of the gut microbiota with alterations in microbial metabolites, epigenetic rearrangements of DNA and histones, and disruption of serotonergic and dopaminergic signaling. Collectively, these biological alterations affect processes such as synaptogenesis, neuroimmune maturation, and neuroplasticity, and sex-specific and even multigenerational effects have been reported in animal studies. Although the presence of familial factors and socioeconomic conditions makes it difficult to draw causal conclusions in human studies, the body of evidence supports the existence of a real biological vulnerability. Various interventions, including improved maternal nutrition, n-3 fatty acid intake, antioxidant strategies, and prenatal physical activity, have shown promising potential to improve metabolic and inflammatory status during pregnancy. Understanding these intertwined mechanisms highlights the importance of early prevention and implementation of targeted maternal health strategies to achieve the best neurodevelopmental outcomes in offspring.
Determinants of midgut loop formation: Influence of midgut length, diameter, and location.
Ishida N, Kanahashi T, Matsubayashi J … +5 more , Fujii S, Imai H, Otani H, Yamada S, Takakuwa T
Dev Dyn · 2026 May · PMID 42183615 · Publisher ↗
BACKGROUND: The midgut forms tertiary loops in the extraembryonic coelom, where biomechanical factors are thought to influence this process. The number of loops may stabilize once the midgut returns to the abdominal cavi...
BACKGROUND: The midgut forms tertiary loops in the extraembryonic coelom, where biomechanical factors are thought to influence this process. The number of loops may stabilize once the midgut returns to the abdominal cavity. We therefore examined how midgut length and diameter affect the number of tertiary loops before and after intestinal return. RESULTS: Magnetic resonance images from 50 human embryo and fetus specimens and serial tissue sections from six fetuses were analyzed. The midgut was divided into four segments, and the length of each segment and the tube diameter at a representative central loop were measured and subjected to regression analysis. In the extraembryonic coelom, loop number increased linearly with midgut length, whereas diameter showed no independent association. In the abdominal cavity, greater length was associated with more loops, whereas greater diameter tended to be associated with fewer loops, particularly in Segment-2 and Segment-4. This pattern may be related to the apparent attenuation of further loop increase after return to the abdominal cavity during later fetal development. CONCLUSIONS: The effects of midgut length and diameter on tertiary loop formation differ between the extraembryonic coelom and the abdominal cavity, highlighting the importance of midgut position in loop formation.
Spatiotemporal dynamics of mTORC1 and mTORC2 in the developing spinal cord and their essential roles in gliogenesis.
Sasaki R, Sasai N, Shinozuka T
Dev Dyn · 2026 May · PMID 42169251 · Publisher ↗
BACKGROUND: Mechanistic target of rapamycin (mTOR) is a serine/threonine kinase with diverse roles in development and homeostasis, but its spatiotemporal dynamics in the embryonic spinal cord are not fully defined. Here,...
BACKGROUND: Mechanistic target of rapamycin (mTOR) is a serine/threonine kinase with diverse roles in development and homeostasis, but its spatiotemporal dynamics in the embryonic spinal cord are not fully defined. Here, we map mTOR activity across mouse spinal cord development and test its function using a conditional gene mutant. RESULTS: Immunohistochemistry for phosphorylated readouts of mTORC1 and mTORC2 revealed distinct, stage-dependent patterns. In the early neural tube, phosphorylated S6 (p-S6; Ser235/236 and Ser240/244) marked dorsal progenitors and ventral motor neurons, while p-p70S6K, p-4E-BP1, and p-Akt (Ser473) were enriched along the luminal surface where mitoses occur. By E13.5, p-S6 persisted in the motor column, whereas p-p70S6K, p-4E-BP1, and luminal p-Akt remained ventricular; at E18.5, robust p-S6 and p-p70S6K signals were localized to neuronal somata and fibers in the marginal layer, with minimal p-Akt. Closer examination revealed that mTORC1/2 signals preferentially colocalized with pHH3-positive ventricular progenitors early, then decoupled as development progressed. Within motor neurons, mTORC1 broadly overlapped with Islet1, including the Lhx3-positive medial motor column (MMC), whereas mTORC2 (p-Akt) labeled an Islet1-positive subset complementary to Lhx3 and declined over time, demarcating lateral, non-MMC domains. Nestin-Cre-mediated mTOR deletion did not overtly affect neuronal organization but reduced GFAP- and Sox10-positive glial lineage cells, indicating a selective requirement of mTOR for glial differentiation. CONCLUSIONS: Together, the data suggest separable and temporal roles of mTORC1 and mTORC2 in progenitor mitosis, motor-neuron domain organization, and late embryonic gliogenesis.
Zebrafish inversin mutants develop scoliosis in the absence of laterality defects.
Derrick CJ, Eley L, Henderson DJ … +1 more , Chaudhry B
Dev Dyn · 2026 May · PMID 42169231 · Publisher ↗
BACKGROUND: Human mutations in INVERSIN are associated with nephronophthisis, variable penetrance of situs inversus and congenital heart disease. Inversin has been shown to localize to cilia and many of the patient pheno...
BACKGROUND: Human mutations in INVERSIN are associated with nephronophthisis, variable penetrance of situs inversus and congenital heart disease. Inversin has been shown to localize to cilia and many of the patient phenotypes are attributed to disrupted cilia function. We set out to characterize the invs allele in zebrafish to investigate its utility in understanding patient disease. RESULTS: The left-right axis is established correctly in invs mutants, kidneys appear to develop normally without any cysts and cilia appear normal, however mutants are significantly shorter. In post-embryonic stages, invs mutants display significant growth delay and signs of retinal mis-patterning together with spinal deformities reminiscent of idiopathic scoliosis. The allele is lethal in the juvenile stage. CONCLUSIONS: We show that invs allele has a distinct phenotype from other models where inversin function is disrupted, uncovering novel roles in post-embryonic development.
BOOPTHAT: An inexpensive and scalable system for spatiotemporal activation of heat-shock transgenes in zebrafish.
Wang D, Martin BL
Dev Dyn · 2026 May · PMID 42163004 · Publisher ↗
BACKGROUND: Gaining finer spatiotemporal control over gene expression is critical for unraveling the regulatory networks that coordinate embryogenesis. While the heat-shock inducible gene expression system is a widely us...
BACKGROUND: Gaining finer spatiotemporal control over gene expression is critical for unraveling the regulatory networks that coordinate embryogenesis. While the heat-shock inducible gene expression system is a widely used tool for controlling temporal transgene expression, its applicability in spatiotemporal control is limited. RESULTS: We present the BOOPTHAT (Batch-Operating Optically Powered Targeted Heater for Activating Transgenes) as a low-cost system for activating heat-shock inducible transgenes with spatiotemporal control in multiple zebrafish embryos at a time. The BOOPTHAT system is built from 3D printed components and inexpensive consumer parts. Independent 3D printed micromanipulators are used to position optical fiber probes. When coupled to a light source, the probes are heated photothermally and are used to perform targeted gene activation in multiple samples at a time. CONCLUSIONS: By adding a level of spatial control onto the well-established system of heat-shock inducible transgenes, we take advantage of the existing infrastructure surrounding the heat-shock induction system and introduce new ways to use the multitude of existing lines. We demonstrate the capabilities of our system and highlight some areas of research that stand to benefit from this frugal and effective system.
An accessible microfluidic perfusion platform for time-restricted control of zebrafish embryonic patterning.
Nakhuda M, Simsek MF
Dev Dyn · 2026 May · PMID 42157413 · Publisher ↗
Understanding the dynamic nature of developmental networks requires live imaging techniques capable of capturing real-time developmental processes in wild-type and mutant embryos as they are exposed to pharmacological pe...
Understanding the dynamic nature of developmental networks requires live imaging techniques capable of capturing real-time developmental processes in wild-type and mutant embryos as they are exposed to pharmacological perturbations. A peculiar developmental patterning process in early vertebrate embryos is the sequential segmentation of bilateral somites from the unsegmented tail tissue along their major axis. Earlier work discovered that segmentation is instructed by an oscillatory fibroblast growth factor (Fgf)/ERK signaling gradient sourced from the tailbud. Somite segmentation was recapitulated at will in the absence of the molecular oscillator, "the segmentation clock", via pulsatile drug inhibitions. Here, we present a live imaging setup for zebrafish embryos that incorporates a 3D-printed chamber and a programmed syringe pump for precise, automated, periodic drug delivery. The chamber secures the orientation of zebrafish embryos in agarose inserts and incorporates inflow and outflow ports to facilitate controlled drug perfusion. Servo motors controlled by an Arduino were integrated to automate valve switching, achieving fully automated exchange of two different fluids for alternating drug delivery and rinse cycles. Such periodic delivery of an inhibitor drug entrains the Fgf/ERK signaling gradient in the embryonic tail to oscillate in clock-deficient mutants, creating lab-reconstituted somites in otherwise defective embryos. Embryos expressing fluorescent markers can further be imaged at single-cell resolution during perturbations. Overall, this system provides a cost-effective, reproducible platform for investigating vertebrate development and interrogating cellular decision-making under controlled experimental conditions. We anticipate this setup will be broadly beneficial for the biomedical research community interested in controlled drug delivery and in vivo cellular dynamics.
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