Comparative analysis of human and mouse development: From zygote to pre-gastrulation.
etz M Abstract Development of the mammalian embryo begins with formation of the totipotent zygote during fertilization. This initial cell is able to give rise to every embryonic tissue of the developing organism as well as all extra-embryonic lineages, such as the placenta and the yolk sac, which are essential for the initial patterning and support growth of the fetus until birth. As the embryo transits from pre- to post-implantation, major structural and transcriptional changes occur within the embryonic lineage to set up the basis for the subsequent phase of gastrulation. Fine-tuned coordination of cell division...
Source: Current Topics in Developmental Biology - January 23, 2020 Category: Biology Authors: Molè MA, Weberling A, Zernicka-Goetz M Tags: Curr Top Dev Biol Source Type: research

The cellular and molecular mechanisms that establish the mechanics of Drosophila gastrulation.
Abstract In this review, we cover advances in the field that have contributed to our mechanistic understanding of how tissues internalize during Drosophila melanogaster gastrulation. The changes in tissue shape and architecture that are associated with mesoderm and endoderm invagination in the early Drosophila embryo are accompanied by cell shape changes which are driven by actomyosin contractility. The activation of signal transduction pathways is patterned by embryonic transcription factors, which define distinct geometries of gene expression and the tissue contractile domains. At the subcellular level, outputs ...
Source: Current Topics in Developmental Biology - January 23, 2020 Category: Biology Authors: Ko CS, Martin AC Tags: Curr Top Dev Biol Source Type: research

Cellular, molecular, and biophysical control of epithelial cell intercalation.
en JA Abstract Convergent extension is a conserved mechanism for elongating tissues. In the Drosophila embryo, convergent extension is driven by planar polarized cell intercalation and is a paradigm for understanding the cellular, molecular, and biophysical mechanisms that establish tissue structure. Studies of convergent extension in Drosophila have provided key insights into the force-generating molecules that promote convergent extension in epithelial tissues, as well as the global systems of spatial information that systematically organize these cell behaviors. A general framework has emerged in which asymmetr...
Source: Current Topics in Developmental Biology - January 23, 2020 Category: Biology Authors: Paré AC, Zallen JA Tags: Curr Top Dev Biol Source Type: research

Gastrulation in the sea urchin.
Abstract Gastrulation is arguably the most important evolutionary innovation in the animal kingdom. This process provides the basic embryonic architecture, an inner layer separated from an outer layer, from which all animal forms arise. An extraordinarily simple and elegant process of gastrulation is observed in the sea urchin embryo. The cells participating in sea urchin gastrulation are specified early during cleavage. One outcome of that specification is the expression of transcription factors that control each of the many subsequent morphogenetic changes. The first of these movements is an epithelial-mesenchym...
Source: Current Topics in Developmental Biology - January 23, 2020 Category: Biology Authors: McClay DR, Warner J, Martik M, Miranda E, Slota L Tags: Curr Top Dev Biol Source Type: research

Tunicate gastrulation.
Abstract Tunicates are a diverse group of invertebrate marine chordates that includes the larvaceans, thaliaceans, and ascidians. Because of their unique evolutionary position as the sister group of the vertebrates, tunicates are invaluable as a comparative model and hold the promise of revealing both conserved and derived features of chordate gastrulation. Descriptive studies in a broad range of tunicates have revealed several important unifying traits that make them unique among the chordates, including invariant cell lineages through gastrula stages and an overall morphological simplicity. Gastrulation has only...
Source: Current Topics in Developmental Biology - January 23, 2020 Category: Biology Authors: Winkley KM, Kourakis MJ, DeTomaso AW, Veeman MT, Smith WC Tags: Curr Top Dev Biol Source Type: research

Mesoderm and endoderm internalization in the Xenopus gastrula.
Abstract Mesoderm and endoderm internalization in the Xenopus embryo are based on a number of region-specific morphogenetic processes that co-act in the vegetal half of the gastrula. In the multilayered wall surrounding the blastocoel, the apical layer engages in bottle cell formation and associated invagination and involution movements, and in cell intercalation in the plane of the layer. Of these epithelial-type processes, only bottle cell formation has been analyzed mechanistically. In the deep layers of the blastocoel wall, cell-on-cell migration drives the internalization of mesoderm by various forms of invol...
Source: Current Topics in Developmental Biology - January 23, 2020 Category: Biology Authors: Winklbauer R Tags: Curr Top Dev Biol Source Type: research

Convergent extension in the amphibian, Xenopus laevis.
Abstract This review is a comprehensive analysis of the cell biology and biomechanics of Convergent Extension in Xenopus. PMID: 31959291 [PubMed - in process] (Source: Current Topics in Developmental Biology)
Source: Current Topics in Developmental Biology - January 23, 2020 Category: Biology Authors: Keller R, Sutherland A Tags: Curr Top Dev Biol Source Type: research

Setting up for gastrulation: D. melanogaster.
Abstract Drosophila melanogaster embryos develop initially as a syncytium of totipotent nuclei and subsequently, once cellularized, undergo morphogenetic movements associated with gastrulation to generate the three somatic germ layers of the embryo: mesoderm, ectoderm, and endoderm. In this chapter, we focus on the first phase of gastrulation in Drosophila involving patterning of early embryos when cells differentiate their gene expression programs. This patterning process requires coordination of multiple developmental processes including genome reprogramming at the maternal-to-zygotic transition, combinatorial a...
Source: Current Topics in Developmental Biology - January 23, 2020 Category: Biology Authors: Stathopoulos A, Newcomb S Tags: Curr Top Dev Biol Source Type: research

Mechanisms of zebrafish epiboly: A current view.
Abstract Epiboly is a conserved gastrulation movement describing the thinning and spreading of a sheet or multi-layer of cells. The zebrafish embryo has emerged as a vital model system to address the cellular and molecular mechanisms that drive epiboly. In the zebrafish embryo, the blastoderm, consisting of a simple squamous epithelium (the enveloping layer) and an underlying mass of deep cells, as well as a yolk nuclear syncytium (the yolk syncytial layer) undergo epiboly to internalize the yolk cell during gastrulation. The major events during zebrafish epiboly are: expansion of the enveloping layer and the inte...
Source: Current Topics in Developmental Biology - January 23, 2020 Category: Biology Authors: Bruce AEE, Heisenberg CP Tags: Curr Top Dev Biol Source Type: research

Setting up for gastrulation in zebrafish.
Abstract Soon after fertilization the zebrafish embryo generates the pool of cells that will give rise to the germline and the three somatic germ layers of the embryo (ectoderm, mesoderm and endoderm). As the basic body plan of the vertebrate embryo emerges, evolutionarily conserved developmental signaling pathways, including Bmp, Nodal, Wnt, and Fgf, direct the nearly totipotent cells of the early embryo to adopt gene expression profiles and patterns of cell behavior specific to their eventual fates. Several decades of molecular genetics research in zebrafish has yielded significant insight into the maternal and ...
Source: Current Topics in Developmental Biology - January 23, 2020 Category: Biology Authors: Marlow FL Tags: Curr Top Dev Biol Source Type: research

Zebrafish gastrulation: Putting fate in motion.
Abstract Gastrulation entails specification and formation of three embryonic germ layers-ectoderm, mesoderm and endoderm-thereby establishing the basis for the future body plan. In zebrafish embryos, germ layer specification occurs during blastula and early gastrula stages (Ho & Kimmel, 1993), a period when the main morphogenetic movements underlying gastrulation are initiated. Hence, the signals driving progenitor cell fate specification, such as Nodal ligands from the TGF-β family, also play key roles in regulating germ layer progenitor cell segregation (Carmany-Rampey & Schier, 2001; David & Ro...
Source: Current Topics in Developmental Biology - January 23, 2020 Category: Biology Authors: Pinheiro D, Heisenberg CP Tags: Curr Top Dev Biol Source Type: research

Cellular and molecular mechanisms of convergence and extension in zebrafish.
Abstract Gastrulation is the period of development when the three germ layers, mesoderm, endoderm and ectoderm, are not only formed, but also shaped into a rudimentary body plan. An elongated anteroposterior (AP) axis is a key feature of all vertebrate body plans, and it forms during gastrulation through the highly conserved morphogenetic mechanism of convergence & extension (C&E). As the name suggests, this process requires that cells within each germ layer converge toward the dorsal midline to narrow the tissue in the mediolateral (ML) dimension and concomitantly extend it in the AP dimension. In a numbe...
Source: Current Topics in Developmental Biology - January 23, 2020 Category: Biology Authors: Williams MLK, Solnica-Krezel L Tags: Curr Top Dev Biol Source Type: research

Movements of chick gastrulation.
Abstract In birds as in all amniotes, the site of gastrulation is a midline structure, the primitive streak. This appears as cells in the one cell-thick epiblast undergo epithelial-to-mesenchymal transition to ingress and form definitive mesoderm and endoderm. Global movements involving tens of thousands of cells in the embryonic epiblast precede gastrulation. They position the primitive streak precursors from a marginal position (equivalent to the situation in anamniotes) along the future antero-posterior axis (typical for amniotes). These epithelial movements continue in modified form during gastrulation, when t...
Source: Current Topics in Developmental Biology - January 23, 2020 Category: Biology Authors: Voiculescu O Tags: Curr Top Dev Biol Source Type: research

Guts and gastrulation: Emergence and convergence of endoderm in the mouse embryo.
Abstract Gastrulation is a central process in mammalian development in which a spatiotemporally coordinated series of events driven by cross-talk between adjacent embryonic and extra-embryonic tissues results in stereotypical morphogenetic cell behaviors, massive cell proliferation and the acquisition of distinct cell identities. Gastrulation provides the blueprint of the body plan of the embryo, as well as generating extra-embryonic cell types of the embryo to make a connection with its mother. Gastrulation involves the specification of mesoderm and definitive endoderm from pluripotent epiblast, concomitant with ...
Source: Current Topics in Developmental Biology - January 23, 2020 Category: Biology Authors: Nowotschin S, Hadjantonakis AK Tags: Curr Top Dev Biol Source Type: research

Signaling events regulating embryonic polarity and formation of the primitive streak in the chick embryo.
Abstract The avian embryo is a key experimental model system for early development of amniotes. One key difference with invertebrates and "lower" vertebrates like fish and amphibians is that amniotes do not rely so heavily on maternal messages because the zygotic genome is activated very early. Early development also involves considerable growth in volume and mass of the embryo, with cell cycles that include G1 and G2 phases from very early cleavage. The very early maternal to zygotic transition also allows the embryo to establish its own polarity without relying heavily on maternal determinants. In many...
Source: Current Topics in Developmental Biology - January 23, 2020 Category: Biology Authors: Raffaelli A, Stern CD Tags: Curr Top Dev Biol Source Type: research

Preface.
PMID: 31959300 [PubMed - in process] (Source: Current Topics in Developmental Biology)
Source: Current Topics in Developmental Biology - January 23, 2020 Category: Biology Authors: Solnica-Krezel L Tags: Curr Top Dev Biol Source Type: research

The vertebrate Balbiani body, germ plasm, and oocyte polarity.
Abstract The fate of future generations depends on a high-quality germ line. For a female to successfully produce offspring, her oocytes must be successfully specified and their contents meticulously organized. Germ cells are specified by two general mechanisms: inductive and inherited. In the inductive mechanism, the primordial germ cells (PGCs) are induced by signals from the surrounding cells. In the inherited mechanism, PGCs are specified by passing localized germ plasm material from the oocyte to the future germ cells. The Balbiani body, a conserved oocyte aggregate, facilitates the organization of the oocyte...
Source: Current Topics in Developmental Biology - June 5, 2019 Category: Biology Authors: Jamieson-Lucy A, Mullins MC Tags: Curr Top Dev Biol Source Type: research

From worm to germ: Germ cell development and regeneration in planarians.
Abstract The specification and proper differentiation of germ cells ensure the propagation of sexually reproducing species. Studies of a wide range of organisms have uncovered several important, conserved features of germ cell development, including the critical roles played by localized niches and somatically derived systemic cues. The planarian Schmidtea mediterranea is an excellent model to study fundamental aspects of germ cell development. Planarians are well known for their remarkable regenerative abilities and can regenerate whole animals from small tissue fragments. This amazing ability is bestowed by neob...
Source: Current Topics in Developmental Biology - June 5, 2019 Category: Biology Authors: Issigonis M, Newmark PA Tags: Curr Top Dev Biol Source Type: research

Heterogeneity of primordial germ cells.
Abstract Primordial germ cells (PGCs) must complete a complex and dynamic developmental program during embryogenesis to establish the germline. This process is highly conserved and involves a diverse array of tasks required of PGCs, including migration, survival, sex differentiation, and extensive epigenetic reprogramming. A common theme across many organisms is that PGC success is heterogeneous: only a portion of all PGCs complete all these steps while many other PGCs are eliminated from further germline contribution. The differences that distinguish successful PGCs as a population are not well understood. Here, ...
Source: Current Topics in Developmental Biology - June 5, 2019 Category: Biology Authors: Nguyen DH, Jaszczak RG, Laird DJ Tags: Curr Top Dev Biol Source Type: research

Germline stem cell homeostasis.
Abstract In many species, germline stem cells (GSCs) function to sustain gametogenesis throughout the life of organismal life span. As the source of gametes, the only cell type that can pass the genetic information to the next generation, GSCs play a fundamental role in maximizing the quantity of gametes that animals produce, while ensuring their highest quality. GSCs are maintained by the signals from their niches, and germ cells that exited the niche undergo differentiation to generate functional gametes. GSC population is sustained by a multitude of mechanisms such as asymmetric stem cell divisions and dediffer...
Source: Current Topics in Developmental Biology - June 5, 2019 Category: Biology Authors: Nelson JO, Chen C, Yamashita YM Tags: Curr Top Dev Biol Source Type: research

Heterogeneous, dynamic, and stochastic nature of mammalian spermatogenic stem cells.
Abstract Mammalian testes produce a huge number of sperm over a long period. This process, essential for the continuity of life, depends on the delicate balance of self-renewal and differentiation of resident stem cells, termed spermatogenic (spermatogonial) stem cells or SSCs. SSCs have motivated many researchers to query their identity, behavior, and regulation in the tissue microenvironment. The study of SSCs has a long and prominent history: Taking advantage of the unique organization of the seminiferous tubules, and the accompanying seminiferous epithelial cycle and spermatogenic wave, intricate concepts of S...
Source: Current Topics in Developmental Biology - June 5, 2019 Category: Biology Authors: Yoshida S Tags: Curr Top Dev Biol Source Type: research

Sperm success and immunity.
Abstract The moment of the fertilization of an egg by a spermatozoon-the point of "sperm success"-is a key milestone in the biology of sexually reproducing species and is a fundamental requirement for offspring production. Fertilization also represents the culmination of a suite of sexually selected processes in both sexes and is commonly used as a landmark to measure reproductive success. Sperm success is heavily dependent upon interactions with other key aspects of male and female biology, with the immune system among the most important. The immune system is vital to maintaining health in both sexes; h...
Source: Current Topics in Developmental Biology - June 5, 2019 Category: Biology Authors: Wigby S, Suarez SS, Lazzaro BP, Pizzari T, Wolfner MF Tags: Curr Top Dev Biol Source Type: research

A symbiont's guide to the germline.
Abstract Microbial symbioses exhibit astounding adaptations, yet all symbionts face the problem of how to reliably associate with host offspring every generation. A common strategy is vertical transmission, in which symbionts are directly transmitted from the female to her offspring. The diversity of symbionts and vertical transmission mechanisms is as expansive as the diversity of eukaryotic host taxa that house them. However, there are several common themes among these mechanisms based on the degree to which symbionts associate with the host germline during transmission. In this review, we detail three distinct ...
Source: Current Topics in Developmental Biology - June 5, 2019 Category: Biology Authors: Russell SL, Chappell L, Sullivan W Tags: Curr Top Dev Biol Source Type: research

Genetic basis for primordial germ cells specification in mouse and human: Conserved and divergent roles of PRDM and SOX transcription factors.
Abstract Primordial germ cells (PGCs) are embryonic precursors of sperm and egg that pass on genetic and epigenetic information from one generation to the next. In mammals, they are induced from a subset of cells in peri-implantation epiblast by BMP signaling from the surrounding tissues. PGCs then initiate a unique developmental program that involves comprehensive epigenetic resetting and repression of somatic genes. This is orchestrated by a set of signaling molecules and transcription factors that promote germ cell identity. Here we review significant findings on mammalian PGC biology, in particular, the geneti...
Source: Current Topics in Developmental Biology - June 5, 2019 Category: Biology Authors: Sybirna A, Wong FCK, Surani MA Tags: Curr Top Dev Biol Source Type: research

Germ cell reprogramming.
Abstract Germ cells undergo epigenome reprogramming for proper development of the next generation. The achievement of in vitro germ cell derivation from human and mouse pluripotent stem cells and further differentiation in a plane culture and in aggregation with gonadal somatic cells offers unprecedented opportunities for investigation of the germ cell development. Moreover, advances in low-input/single-cell genomics have enabled detailed investigation of epigenome dynamics during germ cell development. These technologies have advanced our knowledge of epigenome reprogramming during the specification and developme...
Source: Current Topics in Developmental Biology - June 5, 2019 Category: Biology Authors: Kurimoto K, Saitou M Tags: Curr Top Dev Biol Source Type: research

Preface.
PMID: 31155365 [PubMed - in process] (Source: Current Topics in Developmental Biology)
Source: Current Topics in Developmental Biology - June 5, 2019 Category: Biology Authors: Lehmann R Tags: Curr Top Dev Biol Source Type: research

Evolution and meiotic organization of heteromorphic sex chromosomes.
r F Abstract The evolution of heteromorphic sex chromosomes has occurred independently many times in different lineages. The differentiation of sex chromosomes leads to dramatic changes in sequence composition and function and guides the evolutionary trajectory and utilization of genes in pivotal sex determination and reproduction roles. In addition, meiotic recombination and pairing mechanisms are key in orchestrating the resultant impact, retention and maintenance of heteromorphic sex chromosomes, as the resulting exposure of unpaired DNA at meiosis triggers ancient repair and checkpoint pathways. In this review...
Source: Current Topics in Developmental Biology - April 20, 2019 Category: Biology Authors: Daish T, Grützner F Tags: Curr Top Dev Biol Source Type: research

Genetic regulation of sex determination and maintenance in zebrafish (Danio rerio).
Abstract Over the last several decades zebrafish (Danio rerio) has become a major model organism for the study of vertebrate development and physiology. Given this, it may be surprising how little is known about the mechanism that zebrafish use to determine sex. While zebrafish are a gonochoristic species (having two sexes) that do not switch sex as adults, it was appreciated early on that sex ratios obtained from breeding lab domesticated lines were not typically a 1:1 ratio of male and female, suggesting that sex was not determined by a strict chromosomal mechanism. Here we will review the recent progress toward...
Source: Current Topics in Developmental Biology - April 20, 2019 Category: Biology Authors: Kossack ME, Draper BW Tags: Curr Top Dev Biol Source Type: research

Regulation of germ cell sex identity in medaka.
Abstract Germline stem cells are sexually indifferent or flexible even in the mature ovary and testis. Acquiring sex identity consistent with the sex of the body is a critical issue in germline stem cells for producing eggs or sperm. However, the molecular mechanism of the sexual fate decision in germ cells is unclear. Medaka is the first vertebrate in which germline stem cells were found in the mature ovary (Nakamura, Kobayashi, Nishimura, Higashijima, & Tanaka, 2010), and a germ cell autonomous switch gene involved in the sexual fate decision, foxl3, was identified (Nishimura et al., 2015) in vertebrates. He...
Source: Current Topics in Developmental Biology - April 20, 2019 Category: Biology Authors: Tanaka M Tags: Curr Top Dev Biol Source Type: research

Characterizing the bipotential mammalian gonad.
eld A Abstract Primary sex determination is the decision by which the bipotential embryonic gonad commits to either the testicular or ovarian fate. The developing gonad constitutes a unique paradigm for the study of lineage specification, cell fate commitment and the exploration of how distinct cell populations diverge from multipotent progenitors. After the separation of the adreno-gonadal primordium into two distinct primordia, somatic progenitor cells of the gonadal primordium undergo several cell fate decisions and sex-specific cell differentiation. The specification of the supporting and steroidogenic cell li...
Source: Current Topics in Developmental Biology - April 20, 2019 Category: Biology Authors: Nef S, Stévant I, Greenfield A Tags: Curr Top Dev Biol Source Type: research

Role of epigenetic regulation in mammalian sex determination.
Abstract Mammalian sex determination is triggered by activation of the mammalian sex-determining gene, Sry, in a spatially and temporally controlled manner. Because reduced or delayed Sry expression results in male-to-female sex reversal, male development is highly dependent on the accurate transcription of Sry. SRY dysregulation is a potential cause of human disorders of sex development (DSD). In addition to changes in DNA sequences, gene expression is regulated by epigenetic mechanisms. Epigenetic regulation ensures spatial and temporal accuracy of the expression of developmentally regulated genes. Epigenetic re...
Source: Current Topics in Developmental Biology - April 20, 2019 Category: Biology Authors: Miyawaki S, Tachibana M Tags: Curr Top Dev Biol Source Type: research

The regulation of Sox9 expression in the gonad.
Abstract The bipotential nature of cell types in the early developing gonad and the process of sex determination leading to either testis or ovary differentiation makes this an interesting system in which to study transcriptional regulation of gene expression and cell fate decisions. SOX9 is a transcription factor with multiple roles during development, including being a key player in mediating testis differentiation and therefore subsequent male development. Loss of Sox9 expression in both humans and mice results in XY female development, whereas its inappropriate activation in XX embryonic gonads can give male d...
Source: Current Topics in Developmental Biology - April 20, 2019 Category: Biology Authors: Gonen N, Lovell-Badge R Tags: Curr Top Dev Biol Source Type: research

Sexually dimorphic germ cell identity in mammals.
Abstract Germ cells are the stem cells of the species. Thus, it is critical that we have a good understanding of how they are specified, how the somatic cells instruct and support them, how they commit to one or other sex, and how they ultimately develop into functional gametes. Here, we focus on specifics of how sexual fate is determined during fetal life. Because the majority of relevant experimental work has been done using the mouse model, we focus on that species. We review evidence regarding the identity of instructive signals from the somatic cells, and the molecular responses that occur in germ cells in re...
Source: Current Topics in Developmental Biology - April 20, 2019 Category: Biology Authors: Spiller C, Bowles J Tags: Curr Top Dev Biol Source Type: research

Rethinking sex determination of non-gonadal tissues.
Abstract Evolution of genetic mechanisms of sex determination led to two processes causing sex differences in somatic phenotypes: gonadal differentiation and sex chromosome dosage inequality. In species with heteromorphic sex chromosomes, the sex of the individual is established at the time of formation of the zygote, leading to inherent sex differences in expression of sex chromosome genes beginning as soon as the embryonic transcriptome is activated. The inequality of sex chromosome gene expression causes sexual differentiation of the gonads and of non-gonadal tissues. The difference in gonad type in turn causes...
Source: Current Topics in Developmental Biology - April 20, 2019 Category: Biology Authors: Arnold AP Tags: Curr Top Dev Biol Source Type: research

Translating genomics to the clinical diagnosis of disorders/differences of sex development.
ain E Abstract The medical and psychosocial challenges faced by patients living with Disorders/Differences of Sex Development (DSD) and their families can be alleviated by a rapid and accurate diagnostic process. Clinical diagnosis of DSD is limited by a lack of standardization of anatomical and endocrine phenotyping and genetic testing, as well as poor genotype/phenotype correlation. Historically, DSD genes have been identified through positional cloning of disease-associated variants segregating in families and validation of candidates in animal and in vitro modeling of variant pathogenicity. Owing to the comple...
Source: Current Topics in Developmental Biology - April 20, 2019 Category: Biology Authors: Parivesh A, Barseghyan H, Délot E, Vilain E Tags: Curr Top Dev Biol Source Type: research

Environmental regulation of sex determination in fishes: Insights from Atheriniformes.
ssmann CA Abstract Sex determination is the first step toward the establishment of phenotypic sex in most vertebrates. Aquatic poikilotherms such as teleost fishes exhibit a high diversity of sex-determination mechanisms and gonadal phenotypes that are remarkably plastic and responsive to a variety of environmental factors (e.g., water temperature, pH, salinity, photoperiod, population density). This chapter reviews current knowledge of genotypic and environmental sex determination systems in fishes with special reference to Atheriniformes-one of the best-characterized taxa in this field-and offers perspectives to...
Source: Current Topics in Developmental Biology - April 20, 2019 Category: Biology Authors: Yamamoto Y, Hattori RS, Patiño R, Strüssmann CA Tags: Curr Top Dev Biol Source Type: research

Natural sex change in fish.
Abstract Sexual fate can no longer be considered an irreversible deterministic process that once established during early embryonic development, plays out unchanged across an organism's life. Rather, it appears to be a dynamic process, with sexual phenotype determined through an ongoing battle for supremacy between antagonistic male and female developmental pathways. That sexual fate is not final and is actively regulated via the suppression or activation of opposing genetic networks creates the potential for flexibility in sexual phenotype in adulthood. Such flexibility is seen in many fish, where sex change is a...
Source: Current Topics in Developmental Biology - April 20, 2019 Category: Biology Authors: Gemmell NJ, Todd EV, Goikoetxea A, Ortega-Recalde O, Hore TA Tags: Curr Top Dev Biol Source Type: research

Preface.
PMID: 30999983 [PubMed - in process] (Source: Current Topics in Developmental Biology)
Source: Current Topics in Developmental Biology - April 20, 2019 Category: Biology Authors: Capel B Tags: Curr Top Dev Biol Source Type: research

Stem and progenitor cells in skeletal development.
Abstract Accumulating evidence supports the idea that stem and progenitor cells play important roles in skeletal development. Over the last decade, the definition of skeletal stem and progenitor cells has evolved from cells simply defined by their in vitro behaviors to cells fully defined by a combination of sophisticated approaches, including serial transplantation assays and in vivo lineage-tracing experiments. These approaches have led to better identification of the characteristics of skeletal stem cells residing in multiple sites, including the perichondrium of the fetal bone, the resting zone of the postnata...
Source: Current Topics in Developmental Biology - March 25, 2019 Category: Biology Authors: Ono N, Balani DH, Kronenberg HM Tags: Curr Top Dev Biol Source Type: research

Joints in the appendicular skeleton: Developmental mechanisms and evolutionary influences.
We describe previous studies, and include new data, on the knee joints of aquatic axolotls that unlike those in higher vertebrates, are not cavitated, are filled with rigid fibrous tissues and resemble amphiarthroses. We show that when axolotls metamorph to life on land, their intra-knee fibrous tissue becomes sparse and seemingly more flexible and the articular cartilage becomes distinct and acquires a tidemark. In sum, there have been considerable advances toward a better understanding of limb joint development, biological responsiveness, and evolutionary influences, though much remains unclear. Future progress in these ...
Source: Current Topics in Developmental Biology - March 25, 2019 Category: Biology Authors: Rux D, Decker RS, Koyama E, Pacifici M Tags: Curr Top Dev Biol Source Type: research

BMPs, TGF β, and border security at the interzone.
BMPs, TGFβ, and border security at the interzone. Curr Top Dev Biol. 2019;133:153-170 Authors: Lyons KM, Rosen V Abstract Synovial joints enable movement and protect the integrity of the articular cartilage. Joints form within skeletal condensations destined to undergo chondrogenesis. The suppression of this chondrogenic program in the interzone is the first morphological sign of joint formation. While we have a fairly good understanding of the essential roles of BMP and TGFβ family members in promoting chondrogenic differentiation in developing skeletal elements, we know very little about h...
Source: Current Topics in Developmental Biology - March 25, 2019 Category: Biology Authors: Lyons KM, Rosen V Tags: Curr Top Dev Biol Source Type: research

Roles and regulation of SOX transcription factors in skeletogenesis.
Abstract SOX transcription factors participate in the specification, differentiation and activities of many cell types in development and beyond. The 20 mammalian family members are distributed into eight groups based on sequence identity, and while co-expressed same-group proteins often have redundant functions, different-group proteins typically have distinct functions. More than a handful of SOX proteins have pivotal roles in skeletogenesis. Heterozygous mutations in their genes cause human diseases, in which skeletal dysmorphism is a major feature, such as campomelic dysplasia (SOX9), or a minor feature, such ...
Source: Current Topics in Developmental Biology - March 25, 2019 Category: Biology Authors: Lefebvre V Tags: Curr Top Dev Biol Source Type: research

Fibroblast growth factors in skeletal development.
Abstract Fibroblast growth factors (FGFs) and their receptors (FGFRs) are expressed throughout all stages of skeletal development. In the limb bud and in cranial mesenchyme, FGF signaling is important for formation of mesenchymal condensations that give rise to bone. Once skeletal elements are initiated and patterned, FGFs regulate both endochondral and intramembranous ossification programs. In this chapter, we review functions of the FGF signaling pathway during these critical stages of skeletogenesis, and explore skeletal malformations in humans that are caused by mutations in FGF signaling molecules. PMID:...
Source: Current Topics in Developmental Biology - March 25, 2019 Category: Biology Authors: Ornitz DM, Marie PJ Tags: Curr Top Dev Biol Source Type: research

Wnt-signaling in skeletal development.
Abstract As the vertebrate skeleton develops it progresses from a solely cartilaginous scaffold to a mineralized bony skeleton. The cells that build up the skeleton, the chondrocytes and osteoblasts, are primarily of mesodermal origin. Yet, some facial bones, as well as the endocranium, are derived from neural crest cells. The differentiation of the mesenchymal cells to skeletal precursors as well as their subsequent differentiation and maturation along the two lineages, chondrogenic and osteogenic, is controlled by various different signaling pathways, among them Wnt-signaling. WNTs comprise a family of 19 secret...
Source: Current Topics in Developmental Biology - March 25, 2019 Category: Biology Authors: Teufel S, Hartmann C Tags: Curr Top Dev Biol Source Type: research

ECM signaling in cartilage development and endochondral ossification.
Abstract During cartilage development chondrocytes undergo a multi-step process characterized by consecutive changes in cell morphology and gene expression. Cell proliferation, polarity, differentiation, and migration are influenced by chemical and mechanical signaling between the extracellular matrix (ECM) and the cell. Several structurally diverse transmembrane receptors such as integrins, discoidin domain receptor 2 (DDR 2), and CD44 mediate the crosstalk between cells and their ECM. However, the contribution of cell-matrix interactions during early chondrogenesis and further cartilage development through cell ...
Source: Current Topics in Developmental Biology - March 25, 2019 Category: Biology Authors: Prein C, Beier F Tags: Curr Top Dev Biol Source Type: research

G αs signaling in skeletal development, homeostasis and diseases.
Gαs signaling in skeletal development, homeostasis and diseases. Curr Top Dev Biol. 2019;133:281-307 Authors: Cong Q, Xu R, Yang Y Abstract Skeletal development is exquisitely controlled both spatially and temporally by cell signaling networks. Gαs is the stimulatory α-subunit in a heterotrimeric G protein complex transducing the signaling of G-protein-coupled receptors (GPCRs), responsible for controlling both skeletal development and homeostasis. Gαs, encoded by the GNAS gene in humans, plays critical roles in skeletal development and homeostasis by regulating commitment, dif...
Source: Current Topics in Developmental Biology - March 25, 2019 Category: Biology Authors: Cong Q, Xu R, Yang Y Tags: Curr Top Dev Biol Source Type: research

Importance of the circadian clock in tendon development.
Abstract Tendons are remarkable tissues that transmit force from muscle to bone during joint movement. They are remarkable because they withstand tensile forces that are orders of magnitude greater than can be withstood by isolated cells. The ability of the cells to survive is directly attributable to the stress shielding properties of the collagen-rich extracellular matrix of the tissue. A further remarkable feature is that the vast majority (>98%) of the collagen is never turned over; it is synthesized during embryonic through early adult development and persists for the lifetime of the person. How the collag...
Source: Current Topics in Developmental Biology - March 25, 2019 Category: Biology Authors: Yeung CC, Kadler KE Tags: Curr Top Dev Biol Source Type: research

Mechanistic insights into skeletal development gained from genetic disorders.
Abstract A complex cascade of highly regulated processes of cell fate determination, differentiation, proliferation and transdifferentiation dictate the patterning, morphogenesis and growth of the vertebrate skeleton, perturbation of which results in malformation. In humans over 450 different dysplasias involving the skeletal system constitute a significant fraction of documented Mendelian disorders. The combination of clinical, phenotypic characterization of rare human skeletal dysmorphologies, the discovery of causative mutations and functional validation in animal models has contributed enormously to the unders...
Source: Current Topics in Developmental Biology - March 25, 2019 Category: Biology Authors: Yip RKH, Chan D, Cheah KSE Tags: Curr Top Dev Biol Source Type: research

Development of the axial skeleton and intervertebral disc.
Abstract Development of the axial skeleton is a complex, stepwise process that relies on intricate signaling and coordinated cellular differentiation. Disruptions to this process can result in a myriad of skeletal malformations that range in severity. The notochord and the sclerotome are embryonic tissues that give rise to the major components of the intervertebral discs and the vertebral bodies of the spinal column. Through a number of mouse models and characterization of congenital abnormalities in human patients, various growth factors, transcription factors, and other signaling proteins have been demonstrated ...
Source: Current Topics in Developmental Biology - March 25, 2019 Category: Biology Authors: Williams S, Alkhatib B, Serra R Tags: Curr Top Dev Biol Source Type: research

Regulatory mechanisms of jaw bone and tooth development.
Abstract Jaw bones and teeth originate from the first pharyngeal arch and develop in closely related ways. Reciprocal epithelial-mesenchymal interactions are required for the early patterning and morphogenesis of both tissues. Here we review the cellular contribution during the development of the jaw bones and teeth. We also highlight signaling networks as well as transcription factors mediating tissue-tissue interactions that are essential for jaw bone and tooth development. Finally, we discuss the potential for stem cell mediated regenerative therapies to mitigate disorders and injuries that affect these organs....
Source: Current Topics in Developmental Biology - March 25, 2019 Category: Biology Authors: Yuan Y, Chai Y Tags: Curr Top Dev Biol Source Type: research