Developmental Cell

Specification of the inner cell mass (ICM) and trophectoderm (TE) at the first mammalian cell fate decision requires the transcription factor Tead4, yet what restricts Tead4 activity to presumptive TE cells remains unknown. Tead4 localizes to mitochondria, and the ICM and TE harbor distinct mitochondrial populations, but whether Tead4 distribution varies across mitochondrial subtypes in the cleavage-stage embryo has not been examined. Here we used fluorescence-activated mitochondrial sorting (FAMS) to characterize mitochondrial subpopulations in mouse metaphase-II oocytes and 8-cell embryos with respect to size, mitochondrial membrane potential ({Delta}{Psi}m), and Tead4 protein content. Mitochondria are heterogeneous in size and {Delta}{Psi}m in both developmental stages, with large mitochondria exhibiting markedly higher {Delta}{Psi}m than small mitochondria. Tead4 protein is concentrated in the large, high-{Delta}{Psi}m mitochondrial subpopulation in 8-cell embryos, with 75% of large mitochondria containing Tead4 compared to only 3% of small mitochondria. The overall size distribution of the mitochondrial pool is maintained between oocytes and 8-cell embryos; Tead4 accumulation within the large mitochondrial fraction is therefore a developmentally regulated process initiated specifically during the early embryogenesis. These findings establish for the first time that Tead4 localizes preferentially to large, high-{Delta}{Psi}m mitochondria in the cleavage-stage embryo, providing a previously unrecognized cellular basis for understanding how Tead4 bioavailability may be regulated prior to TE specification.

The neuronal endoplasmic reticulum (ER) extends from the soma into axons and dendrites to coordinate protein trafficking, lipid metabolism, inter-organelle organization, and calcium homeostasis. Conserved genes involved in shaping the tubular ER are implicated in neurodevelopment and neurodegeneration, suggesting that ER structure and dynamics influence neuronal health and drive pathogenesis. However, the links between ER morphology and neuronal function and resilience remain incompletely understood. While models typically depict the neuronal ER as a fully continuous network, here we show that micron-scale ER discontinuities in neurites are unexpectedly common in young, unstressed C. elegans. These discontinuities occur in both axonal and dendritic compartments with a consistent frequency that varies between motor and mechanosensory neuron types. Using live imaging and photokinetic assays of endogenously tagged markers of the ER, we confirm that these gaps reflect true loss of ultrastructural continuity. Subpopulations of ER tubule tips are highly motile, and the majority of ER discontinuities are resolved in less than an hour. Suggesting the formation of discontinuities is linked to cellular damage, their frequency increases with both age and environmental stress. Finally, in agreement with prior observations across models, discontinuities are exacerbated by impairment of certain ER shaping factors involved in hereditary spastic paraplegia, such as reticulon. These findings reveal a model where ER discontinuities are not uncommon in healthy animals, and provide a tractable system in C. elegans to dissect the molecular mechanisms maintaining ER structural homeostasis in vivo.

Thyroid hormone (TH) is a systemic regulator of vertebrate development, yet its role in the maturation of the stratified skin remains poorly defined. Using the skin at the edge of the zebrafish caudal fin, we defined the trajectory of epidermal maturation during the transition from juvenile to adult. We found the peripheral edge (PE) of the fin exhibits positive allometric expansion that is dependent on TH: in thyroid-ablated, hypothyroid backgrounds, the growth of the PE is limited. We showed that TH drives normal PE growth by stimulating both cell proliferation and hypertrophy. Further, we demonstrated that TH acts upstream of the Notch pathway to regulate growth of the PE. While TH signaling machinery is broadly expressed throughout the fin, Notch pathway activation is localized and highly enriched in the PE. Repressing Notch activity prevented PE expansion, while upregulating Notch in a hypothyroid background was sufficient to increase hypertrophy and partially rescue PE expansion. By identifying Notch as a region-specific effector of TH-driven hypertrophy, our findings show a mechanism by which systemic endocrine signals are translated into local tissue morphogenesis. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=92 SRC="FIGDIR/small/713269v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@1381159org.highwire.dtl.DTLVardef@1fb2421org.highwire.dtl.DTLVardef@100fed3org.highwire.dtl.DTLVardef@5a0480_HPS_FORMAT_FIGEXP M_FIG C_FIG

Left-right asymmetry in vertebrate embryos is established by the left-right organizer (LRO), with the zebrafish Kupffers vesicle (KV) providing a tractable model for studying de novo epithelial morphogenesis. During KV formation, dorsal forerunner cells (DFCs) initially form polarized attachments to the enveloping layer (EVL) before reorganizing into multicellular rosettes that precede lumen formation. Here, we show that while DFC-EVL junctions form independently of mitosis, early cytokinetic events play an instructive role in remodeling these contacts. Live imaging and targeted laser ablation reveal that cytokinetic bridges and their associated microtubule bundles recruit actin, seed rosette centers, and promote the transition from external to internal epithelial organization. Disruption of early, but not later, DFC divisions impairs actin accumulation, rosette coalescence, KV detachment from the EVL, and lumenogenesis. These findings identify a temporally restricted role for cytokinesis in organizing cytoskeletal architecture and reveal how division history directs epithelial tissue assembly during LRO development.

Heart regeneration requires coordinated immune activation, timely inflammatory resolution, and dynamic extracellular matrix (ECM) remodeling in addition to cardiomyocyte (CM) proliferation. However, the cytokine signals that instruct immune cell functions during cardiac repair remain incompletely understood. Here, we identify interferon-gamma (IFN-{gamma}) as a critical regulator of macrophage plasticity in zebrafish heart regeneration. IFN-{gamma} signaling components are dynamically activated following cardiac injury, with early induction of ifng1 and temporally coordinated receptor expression. Genetic ablation of ifng1 impairs myocardial regeneration, resulting in reduced CM proliferation and persistent fibrotic scarring. Temporal transcriptional profiling reveals sustained inflammatory signatures, impaired efferocytosis, and abolished reparative programs, accompanied by aberrant immune cell dynamics and retention of injury-derived debris in mutant hearts. Transcriptomic analysis of cardiac macrophages further reveals that IFN-{gamma} deficiency disrupts the transition from an inflammatory state to a reparative, ECM-remodeling phenotype, leading to reduced collagen denaturation and diminished CM protrusion at the injury border zone. Inducible- and macrophage-specific blockade of IFN-{gamma} signaling phenocopies defects in global knockout, establishing a cell-autonomous requirement for IFN-{gamma} in coordinating regenerative immune function. Collectively, our findings define an IFN-{gamma}-dependent macrophage reprogramming axis that couples inflammatory resolution to ECM remodeling in heart regeneration, elucidating how cytokine signaling actively instructs tissue repair. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=118 SRC="FIGDIR/small/712551v1_ufig1.gif" ALT="Figure 1"> View larger version (60K): org.highwire.dtl.DTLVardef@cefbecorg.highwire.dtl.DTLVardef@fd56dborg.highwire.dtl.DTLVardef@517495org.highwire.dtl.DTLVardef@1bd0851_HPS_FORMAT_FIGEXP M_FIG C_FIG

Precise synaptic connectivity emerges through coordinated interactions between neurons and their target cells during development. At the Drosophila embryonic neuromuscular junction (NMJ), postsynaptic muscle fibers actively participate in this process by extending dynamic, actin-rich protrusions termed myopodia that interact with approaching motor growth cones. Previous work focusing on muscle 12 (M12) revealed that myopodia cluster at nascent neuron-muscle contact sites, suggesting that specialized postsynaptic architectures may facilitate synaptic partner selection. However, whether similar morphogenetic strategies operate across the diverse set of embryonic muscles has remained unclear. Here, we establish a genetic imaging toolkit that enables minimally invasive visualization of defined muscle subsets throughout the embryo. Using muscle-specific and stochastic GAL4 drivers to label muscle membranes in vivo, we systematically compare myopodial organization across multiple muscle fibers, including M12, M14, M6, and M7. We find that postsynaptic morphology varies substantially between muscles. M12 displays robust myopodial clustering associated with a prominent sheet-like membrane structure, which we term the muscle lamella, whereas M6 and M14 frequently form myopodial clusters but do not evidently exhibit this structure. In contrast, M7 shows markedly reduced clustering frequency and smaller clusters. These observations reveal previously unrecognized heterogeneity in postsynaptic organization among neighboring muscles during early neuromuscular development. Together, our findings demonstrate that myopodial clustering represents a broadly deployed but differentially organized strategy by which muscles engage motor axons during synaptic partner selection. The imaging toolkit established here provides a foundation for systematic analysis of neuron-muscle interactions across the embryonic musculature and reveals that distinct muscles employ diverse morphogenetic strategies during NMJ assembly.

Classic models of the French flag problem depict sharp cell-type boundaries emerging from threshold responses to morphogen gradients. How discrete cell-type boundaries arise from morphogen signals that vary continuously across developing tissues is not completely understood. We use hair follicle dermal condensate formation to study a sharp developmental transition in which proliferative progenitors undergo cell-cycle exit concurrent with molecular differentiation. Using genetic and genomic approaches, we show that Wnt and Hedgehog signaling interact to coordinate the timing of these two processes. We identify a division of labor between the pathways: Wnt signaling promotes cell-cycle exit by regulating chromatin binding of the Hedgehog mediator GLI3, while Hedgehog signaling induces differentiation genes in a Wnt-dependent manner and simultaneously elevates Wnt activity. When Wnt and Hedgehog activities are temporally aligned, differentiation and cell-cycle exit occur within the same developmental window, restricting both the duration and abundance of intermediate states and producing a sharp cell-type boundary. When these signals are misaligned, intermediate states persist and expand, producing fuzzy boundaries. These findings reveal a mechanism in which interacting morphogen signals regulate the duration and abundance of intermediate states during a developmental transition, thereby controlling how continuous cell-state progression is translated into discrete tissue patterning.

Muller glia are instrumental macroglia of the vertebrate retina, once thought to be a homogeneous population. Now Muller glia are generally accepted as transcriptionally heterogeneous, and new evidence suggests functional diversity may exist in the way these cells respond to retinal injury. It remains unclear, however, whether this functional heterogeneity is limited to a transient phenotype that stems from injury or a fundamental feature of the healthy retina. Here, we investigate Muller glia heterogeneity in the uninjured zebrafish retina across development and adulthood using a comprehensive single-cell transcriptomic atlas of the 5 days post-fertilization (dpf) eye, validated in vivo and integrated with 9 dpf and adult datasets. We reveal that Muller glia are partitioned into three constitutive subpopulations that persist from early larval stages into adulthood: 1) a proliferative and immature population in both the peripheral and central retina; 2) a novel cohort of neuron-associated Muller glia that express coherent transcriptional programs specific to distinct neuronal subtypes, including retinal ganglion, amacrine and horizontal cells; and 3) spatially distinct Muller glia subsets that define a dorso-ventral axis of retinoic acid metabolism, bisected by a novel cyp26c1-expressing equatorial domain. Finally, cross-species analysis reveals that while neuron-associated programs are evolutionarily conserved in mammals, the spatial patterning of morphogens in adult retinae may be specific to the teleost lineage. Collectively, these findings provide robust evidence for intrinsic functional heterogeneity in the uninjured vertebrate retina, reframing Muller glia from a general support population to a specialized cellular network that actively maintains retinal geography and function. Main pointsO_LIZebrafish Muller glia are heterogeneous at 5dpf. C_LIO_LIZebrafish Muller glia subtypes define a spatial axis of retinoic acid metabolism. C_LIO_LINeuron-associated glial programs identified in Zebrafish Muller glia are evolutionarily conserved in mammals. C_LI

Coordinated signaling among neurons, glia, and the vasculature is essential for the formation of a functional nervous system, yet how these relationships emerge during development remains unclear. Here, we investigated the developmental interplay between neural activity, Muller glia, and the retina vasculature in mice. Using quantitative confocal imaging from postnatal day 5 to eye-opening, we mapped the emergence of the superficial, intermediate, and deep vasculature layers and found that they emerged normally in mice lacking the {beta}2-containing nicotinic acetylcholine receptors, despite a dramatic reduction in cholinergic signaling. Tip cell density and overall vessel growth were unchanged, indicating cholinergic wave activity is not required for the emergence of retinal vasculature. We next defined the developmental timeline of Muller glia-vascular interactions. Sparse labeling and immunohistochemistry revealed that Muller glial lateral processes closely associate with endothelial tip cells during intermediate- and deep-layer angiogenesis and establish Aquaporin-4-enriched endfeet at vascular contact sites from the earliest stages of growth, even when vessel trajectories are perturbed. Finally, two-photon calcium imaging combined with simultaneous electrophysiology demonstrated that Muller glial endfeet exhibit robust, compartmentalized calcium transients during development. Although a subset of events was temporally correlated with retinal waves, enhancing neurotransmitter spillover selectively increased wave-associated activity in glial stalks but not endfeet. These findings indicate that calcium signaling at the glial-vascular interface is largely independent of spontaneous neuronal activity. Together, our results support a model in which Muller glia engage growing vessels through an activity-independent, parallel developmental program that may provide instructive cues for retinal angiogenesis.

Neuronal remodeling is a conserved, late developmental mechanism to refine neural circuits. Although remodeling typically occurs with remarkable spatiotemporal precision, its underlying molecular mechanisms remain poorly understood. In the Drosophila mushroom body (MB) circuit, {gamma}-Kenyon cells ({gamma}-KCs) undergo stereotyped remodeling during metamorphosis, in which they prune their larval vertical and medial axonal branches and subsequently regrow a medial, adult-specific branch. Our previous transcriptional profiling of developing {gamma}-KCs revealed dynamic expression of Defective proboscis extension response (Dpr) proteins and their binding partners, Dpr-interacting proteins (DIPs), members of the Immunoglobulin (Ig) superfamily. Despite their established roles in neurodevelopment, how Dpr/DIPs function - given their lack of intracellular domains - remains unclear. Here, we show that overexpression of Dpr4 in developing {gamma}-KCs cell-autonomously inhibits axon pruning. Strikingly, this effect is branch-specific: the vertical axonal branch fails to prune, while the medial branch prunes normally. To our knowledge, this represents the first demonstration of branch-specific control of pruning in this system. Moreover, the adult medial branch regrows normally, indicating that pruning and regrowth are independently regulated at the level of individual branches. We demonstrate that this unique branch-specificity arises from trans-neuronal interactions between Dpr4 in {gamma}-KCs and DIP-{theta} in dopaminergic neurons that selectively innervate the vertical larval MB lobe. Furthermore, our findings suggest that this phenotype relies on an Ig2 domain of a Dpr family member, implying the involvement of a third binding partner. Leveraging this robust overexpression phenotype to probe downstream mechanisms, we find that loss of the transmembrane adhesion protein N-Cadherin suppresses the Dpr4-induced pruning defect. Together, our findings highlight the local impact of Dpr/DIP-mediated trans-neuronal interactions on the spatial regulation of remodeling, and provide genetic evidence implicating N-Cadherin as a potential downstream mediator of Dpr/DIP function within a developing neural circuit.

The intracellular cilia assembly pathway is a complex, multistep process that requires the continuous and coordinated incorporation of membrane material. However, how membrane remodeling occurs during early ciliogenesis is not yet understood. Moreover, the identity of the organelle(s) that supply membrane material for the nascent cilium has yet to be determined. Here, we extend the current model of primary cilia formation by showing that randomly attached distal appendage vesicles and tubules fuse laterally to generate a doughnut-shaped membrane structure. Centripetal fusion events follow to close the central hole. Our data demonstrate that both the Golgi apparatus and endocytotic pathways independently contribute to ciliogenesis. We identify the endocytotic protein GRAF1 as being essential during the early stages of ciliogenesis and for the delivery of plasma membrane-derived material to the developing ciliary membrane. Our three-dimensional ultrastructural analysis uncovers previously unrecognized intermediate stages in the intracellular cilia assembly pathway with GRAF1 as a novel regulator of ciliogenesis.

Colonic stem cells reside in a microenvironment enriched in epidermal growth factor, which is essential for their survival and can activate both PI3K-AKT and MAPK-ERK pathways. This predicts co-activation of both pathways within the growth factor-high stem cell compartment at the base of crypts. However, in patient-derived human colonic organoids and normal human tissue, stem cells maintain robust AKT activity while suppressing ERK signaling despite active EGFR engagement. As stem cells differentiate, they activate pulsatile Erk signaling, which is essential for migration, survival, and maintenance of barrier function. We show that AKT-dependent phosphorylation of Raf-1 at serine 259 establishes a post-receptor checkpoint that maintains ERK temporal dynamics in stem cells. Acute activation of ERK in stem cells triggers rapid global differentiation. Disruption of the ERK checkpoint via mutation of serine 259 leads to sustained AKT and ERK co-activation in stem cells. Unlike ERK/AKT coactivation driven by apoptosis, co-activation in the stem cell compartment results in the emergence of a neoplastic, architecturally disorganized cell population dominating the cell fate profile. Incredibly, introducing brief ERK pulses through Akt inhibition or ERK activation triggers re-differentiation of neoplastic cells. Consistent with duration-dependent MAPK encoding principles, these data demonstrate that regardless of baseline signaling amplitude, ERK signaling dynamics are epistatic to total kinase signaling load in human colonic stem cells.

Animal development is a complex process that requires the coordination of a plethora of pathways in space and time. In several species, the availability of tissue explants has provided a simplified context that facilitates mechanistic investigations, particularly into dynamic events. Here, we demonstrate that extruded C. elegans gonads are a viable tissue explant system for this model organism. Using live-cell imaging, we show that C. elegans gonad explants retain many tissue properties that have been documented in vivo, including mitosis, meiosis, apoptosis and gametogenesis. We further show that C. elegans explants are acutely responsive to treatment by the microtubule depolymerizing drug nocodazole. Our work thus reveals C. elegans gonad explants as a new system in which live-cell imaging and acute drug treatment can be combined to decipher the mechanisms governing germline development.

The metastatic process initiates with collective cell invasion into surrounding tissues and axillary nodes, and subsequent colonization at a distant site. Previously, we found collective invasion is augmented during the G2 cell cycle phase, facilitated through Aurora kinase A (AURKA)-mediated centrosome polarization in the leader cell. Here, we identify cell cycle-associated gene signatures as overrepresented in axilla and liver metastatic sites, with AURKA expression strongly correlated with breast cancer metastasis signatures, and pan-cancer patient survival. Then, we show GFP-AURKA expression endows breast epithelia cells with the ability to form metastatic outgrowths within immune-incompetent chicken embryos. Multi-parametric imaging of wound closure assays reveals phenotypes enabled by, and dependent upon AURKA expression. We discover leader cells express AURKA and acquire front-polarized centrosomes, which differentiates them from other cells in the migrating group. Ectopic expression of GFP-AURKA induces a leader cell phenotype. Conversely, inhibition of AURKA activity alters actin dynamics, promotes turnover of cell contacts, and reduces coordination within migrating groups. Specifically, AURKA interacts with the actin regulator EPLIN, and AURKA inhibition localizes EPLIN to lamellipodia and away from E-cadherin-positive contacts. Inhibiting these necessary roles for AURKA may provide a critical barrier against the metastatic spread of human breast carcinoma cells.

Development of the vertebrate lower jaw depends on spatially precise cell fate decisions by cranial neural crest-derived cells (CNCCs) of the mandibular arch. From closer to the mouth (oral) to farther away (aboral), CNCCs adopt bone, cartilage, tendon, and stromal fates to shape the jaw skeleton and ensure proper connectivity to the musculature. How signaling pathways impact downstream transcriptional programs to generate distinct cell fates along the oral-aboral axis remains incompletely understood. Using photoconversion-based lineage tracing of CNCCs in zebrafish, we show that oral cells contribute to the lower jaw skeleton and aboral cells primarily to tendon, ligament, and stromal tissues. During embryogenesis, the oral domain is partitioned into lateral pitx1+ and medial foxf1+ subdomains distinct from an aboral nr5a2+, gsc+ domain. Using pharmacological inhibition and transgenic misexpression, we find that Bmp signaling establishes aboral nr5a2 and gsc expression, Fgf signaling oral-lateral pitx1 expression, and Hedgehog signaling oral-medial foxf1 expression. Analysis of mutants for pitx1, nr5a2, and gsc reveal that their oral-aboral expression domains are established independently of each other. We also identify enhancers regulating oral-aboral expression of pitx1 and nr5a2, with mutagenesis showing roles for Fgf-dependent ETS motifs in oral pitx1 and Bmp-dependent E-box motifs in aboral nr5a2 enhancer activity, consistent with dependence of nr5a2 expression on the Bmp-dependent E-box factor Hand2. These findings reveal how triangulation of three major signaling pathways converge on distinct gene regulatory modules to establish distinct oral-aboral cell fate decisions in the developing jaw.

Stony corals are the only cnidarians to secrete a robust calcium carbonate skeleton making them the critical keystone species for one of the most diverse marine ecosystems on earth: coral reefs. Despite their importance, very little is known about the genetic interactions that drive the earliest life history stages of corals during which coral-specific traits emerge, such as specification of coral skeletogenic cells. Here, we used a combination of chromatin profiling and gene expression assays to derive the cis-regulatory architectures of early coral development using the emerging model system Astrangia poculata. From this work we found that elements of the cnidarian endomesoderm gene regulatory network have been co-opted into a subnetwork underlying the specification of coral skeleton secreting cells. We further identified the cis-regulatory element responsible for the novel expression of the endomesodermal gene Brachyury in coral skeletogenic cells and demonstrated that this element is capable of reproducing similar expression patterns in Nematostella vectensis, a distantly related species that does not produce a skeleton. These findings support a novel dual role of the endomesodermal GRN in establishing germ layer identity and specifying skeleton secreting cells in stony corals and provide a gene-regulatory framework that underpins the evolution and diversification of stony corals from other cnidarian lineages.

Colonial animals composed of clonally produced units can achieve a high degree of functional integration, challenging the distinction between an individual and a higher-order organism. Siphonophores (Cnidaria: Hydrozoa) exemplify this condition, forming highly organized colonies in which genetically identical zooids are specialized for functions such as locomotion, feeding, and reproduction, and are precisely arranged along a shared stem. All zooids arise from two spatially separated budding zones, the nectosomal and siphosomal growth zones, suggesting that positional information along the stem patterns colony organization at the level of the colony rather than individual zooids. However, the molecular basis of this colony-level axial patterning remains poorly understood. Here, we analyze gene expression along the stem of the siphonophore Agalma okenii using RNA sequencing and in situ hybridization chain reaction (HCR). We show that conserved developmental regulators, including Hox and Wnt pathway genes, exhibit region-specific expression corresponding to distinct budding zones and zooid distributions. These results indicate that canonical axial patterning systems are deployed at the level of the colony axis. Our findings demonstrate that developmental gene networks classically associated with anterior-posterior patterning can operate at a higher level of biological organization, providing a mechanistic framework for the evolution of integrated, superorganism-like body plans in colonial animals.

Successful pregnancy requires exquisite balance: the placenta must invade just enough to access maternal blood but not so deep it remains attached at birth. Disrupting this balance causes life-threatening pregnancy complications, for which treatments remain limited. Animal models are desperately needed to discover mechanisms underlying balanced uteroplacental development and how pregnancy complications arise, but this is hampered by the view that mouse placentation lacks human characteristics such as extensive trophoblast invasion and targeting of uterine spiral arteries. Here, we utilize 3D imaging, mouse genetics, and pharmacological perturbations to demonstrate that: (1) The mouse placenta invades more extensively than previously recognized with most spiral arteries heavily enveloped by fetal trophoblasts, (2) This process is disrupted without CXCL12-CXCR4 signaling specifically during early pregnancy, and (3) Disrupting early uteroplacental development ultimately results in excessively deep trophoblast invasion, closely mimicking the pregnancy complication placenta accreta. Mechanistically, uterine epithelium, stroma, and arteries activate CXCR4 signaling in early pregnancy, and inhibition causes decidualization failure, followed by dissolution of spiral artery development. Trophoblasts consequently migrate deep into uterine muscle and its arteries, reproducing hallmarks of human accreta. Thus, with 3D imaging, the mouse more effectively models human uteroplacental development and defines an early etiological window for intervention.

Precise organ shape during development requires feedback between organ-scale geometry and cell-level growth dynamics. Here, we use the apical hook of dicotyledonous plants as a model to study this multiscale control. This protective structure forms a [~]180{degrees} bend that is stably maintained despite rapid elongation. Combining quantitative growth mapping, multiscale modeling, and hormone analysis, we identify the cellular dynamics underlying hook maintenance. Contrary to the prevailing model, hook stability does not arise from sustained inner-outer growth asymmetry. Instead, stable curvature emerges from a biphasic, self-similar growth pattern that remains spatially fixed despite continuous cell flux. Auxin-driven growth asymmetry induces bending but is spatially restricted and insufficient to maintain shape. By contrast, a graded, auxin-independent autotropic response provides curvature-dependent growth regulation that counteracts bending and stabilizes shape against perturbations. Together, these findings establish a general principle in which local morphogen-driven bending and global geometry-dependent feedback jointly maintain robust organ shape during growth. HighlightsO_LISelf-similar growth maintains apical hook curvature despite continuous cell flux C_LIO_LICurvature stability emerges from coordinated axial and differential growth C_LIO_LIAuxin asymmetry is spatially restricted and insufficient for shape maintenance C_LIO_LICurvature-dependent feedback ensures robust and optimized hook shape C_LI

Ovarian organogenesis relies on the coordinated specification of supporting and steroidogenic lineages from multipotent coelomic epithelium (CE) progenitors. However, it remains unclear how ovarian cellular diversity arises and whether CE progenitors are fate-biased before or after ingression into the gonad. We show that CE cells in fetal mouse and human ovaries are transcriptionally heterogeneous and spatially organized into subdomains already primed toward supporting or steroidogenic identities. CE priming is dynamic, influenced by proximity to the mesonephros, with a transient coexistence of both progenitor types before resolution toward a predominantly supporting-biased CE. In mice, delamination of primed CE cells seeds intragonadal niches that generate pre-granulosa and steroidogenic progenitors. We further demonstrate that fetal steroidogenic progenitors give rise to adult stromal and theca cells, and that granulosa cells have a dual origin from CE-derived and supporting-like cells. Together, these findings reveal a conserved, spatially encoded program of ovarian lineage specification.