The control of somitogenesis in mouse embryos

Development ◽  
1981 ◽  
Vol 65 (Supplement) ◽  
pp. 103-128
Author(s):  
P. P. L. Tam
Keyword(s):  
Body Size ◽  
Primitive Streak ◽  
Mouse Embryos ◽  
The Body ◽  
Whole Body ◽  
Axis Formation ◽  
Presomitic Mesoderm ◽  
Tail Bud ◽  
Somite Formation ◽  
Somitic Mesoderm

Somitogenesis in the mouse embryo commences with the generation of presumptive somitic mesoderm at the primitive streak and in the tail-bud mesenchyme. The presumptive somitic mesoderm is then organized into somite primordia in the presomitic mesoderm. These primordia undergo morphogenesis leading to the segmentation of somites at the cranial end of the presomitic mesoderm. Somite sizes at the time of segmentation vary according to the position of the somite in the body axis: the size of lumbar and sacral somites is nearly twice that of upper trunk somites and of tail somites. The size of the presomitic mesoderm, which is governed by the balance between the addition of cells at the caudal end and the removal of somites at the cranial end, changes during embryonic development. Somitogenesis is disturbed during the compensatory growth of mouse embryos which have suffered a drastic size reduction at the primitive-streak and early-organogenesis stages. The formation of somites is retarded and the upper trunk somites are formed at a smaller size. The embryo also follows an entirely different growth profile, but a normal body size is restored by the early foetal stage. The somite number is regulated to normal and this is brought about by an altered rate of somite formation and the adjustment of somite size in proportion to the whole body size. It is proposed that axis formation and somitogenesis are related morphogenetic processes and that embryonic growth controls the kinetics of somitogenesis, namely by regulating the number of cells allocated to each somite and the rate of somite formation.

The somitogenetic potential of cells in the primitive streak and the tail bud of the organogenesis-stage mouse embryo

Development ◽  
1992 ◽  
Vol 115 (3) ◽  
pp. 703-715 ◽  
Author(s):  
P.P. Tam ◽  
S.S. Tan
Keyword(s):  
Primitive Streak ◽  
Mouse Embryos ◽  
Paraxial Mesoderm ◽  
Tail Bud ◽  
Matrix Interaction ◽  
Cell Matrix ◽  
Age Related ◽  
Somite Formation ◽  
Lateral Mesoderm ◽  
Host Embryo

The developmental potency of cells isolated from the primitive streak and the tail bud of 8.5- to 13.5-day-old mouse embryos was examined by analyzing the pattern of tissue colonization after transplanting these cells to the primitive streak of 8.5-day embryos. Cells derived from these progenitor tissues contributed predominantly to tissues of the paraxial and lateral mesoderm. Cells isolated from older embryos could alter their segmental fate and participated in the formation of anterior somites after transplantation to the primitive streak of 8.5-day host embryo. There was, however, a developmental lag in the recruitment of the transplanted cells to the paraxial mesoderm and this lag increased with the extent of mismatch of developmental ages between donor and host embryos. It is postulated that certain forms of cell-cell or cell-matrix interaction are involved in the specification of segmental units and that there may be age-related variations in the interactive capability of the somitic progenitor cells during development. Tail bud mesenchyme isolated from 13.5-day embryos, in which somite formation will shortly cease, was still capable of somite formation after transplantation to 8.5-day embryos. The cessation of somite formation is therefore likely to result from a change in the tissue environment in the tail bud rather than a loss of cellular somitogenetic potency.

scholarly journals Dynamics of primitive streak regression controls the fate of neuro-mesodermal progenitors in the chicken embryo

2020 ◽  
Author(s):  
Charlene Guillot ◽  
Arthur Michaut ◽  
Brian Rabe ◽  
Olivier Pourquié
Keyword(s):  
Chicken Embryo ◽  
Single Cells ◽  
Primitive Streak ◽  
Clonal Analysis ◽  
Lineage Tracing ◽  
The Body ◽  
Paraxial Mesoderm ◽  
Axis Formation ◽  
Vertebrate Development ◽  
Tail Bud

AbstractIn classical descriptions of vertebrate development, the segregation of the three embryonic germ layers is completed by the end of gastrulation. Body formation then proceeds in a head to tail fashion by progressive deposition of lineage committed progenitors during regression of the Primitive Streak (PS) and tail bud (Pasteels, 1937b; Stern, 2004). Identification of Neuro-Mesodermal Progenitors (NMPs) contributing to both musculo-skeletal precursors (paraxial mesoderm) and spinal cord during axis formation by retrospective clonal analysis challenged these notions (Henrique et al., 2015; Tzouanacou et al., 2009). However, in amniotes such as mouse and chicken, the precise identity and localization of these cells has remained unclear despite a wealth of fate mapping analyses of the PS region. Here, we use lineage tracing in the chicken embryo to show that single cells located in the SOX2/T positive anterior PS region contribute to both neural and mesodermal lineages in the trunk and tail, but only express this bipotential fate with some delay. We demonstrate that posterior to anterior gradients of convergence speed and ingression along the PS gradually lead to exhaustion of all mesodermal precursor territories except for NMPs where limited ingression and increased proliferation maintain and amplify this pool of axial progenitors. As a result, most of the remaining mesodermal precursors from the PS in the tail bud are bipotential NMPs. Together, our results provide a novel understanding of the contribution of the PS and tail bud to the formation of the body of amniote embryos.

scholarly journals Dynamics of primitive streak regression controls the fate of neuromesodermal progenitors in the chicken embryo

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Charlene Guillot ◽  
Yannis Djeffal ◽  
Arthur Michaut ◽  
Brian Rabe ◽  
Olivier Pourquié
Keyword(s):  
Single Cell ◽  
Cell Population ◽  
Chicken Embryo ◽  
Primitive Streak ◽  
Lineage Tracing ◽  
The Body ◽  
Paraxial Mesoderm ◽  
Axis Formation ◽  
Tail Bud ◽  
Transcriptomic Signature

In classical descriptions of vertebrate development, the segregation of the three embryonic germ layers completes by the end of gastrulation. Body formation then proceeds in a head to tail fashion by progressive deposition of lineage-committed progenitors during regression of the primitive streak (PS) and tail bud (TB). The identification by retrospective clonal analysis of a population of neuromesodermal progenitors (NMPs) contributing to both musculoskeletal precursors (paraxial mesoderm) and spinal cord during axis formation challenged these notions. However, classical fate mapping studies of the PS region in amniotes have so far failed to provide direct evidence for such bipotential cells at the single-cell level. Here, using lineage tracing and single-cell RNA sequencing in the chicken embryo, we identify a resident cell population of the anterior PS epiblast, which contributes to neural and mesodermal lineages in trunk and tail. These cells initially behave as monopotent progenitors as classically described and only acquire a bipotential fate later, in more posterior regions. We show that NMPs exhibit a conserved transcriptomic signature during axis elongation but lose their epithelial characteristicsin the TB. Posterior to anterior gradients of convergence speed and ingression along the PS lead to asymmetric exhaustion of PS mesodermal precursor territories. Through limited ingression and increased proliferation, NMPs are maintained and amplified as a cell population which constitute the main progenitors in the TB. Together, our studies provide a novel understanding of the PS and TB contribution through the NMPs to the formation of the body of amniote embryos.

The allocation of cells in the presomitic mesoderm during somite segmentation in the mouse embryo

Development ◽  
1988 ◽  
Vol 103 (2) ◽  
pp. 379-390 ◽  
Author(s):  
P.P. Tam
Keyword(s):  
Mouse Embryo ◽  
Colloidal Gold ◽  
Wheat Germ ◽  
Mouse Embryos ◽  
Middle Region ◽  
Presomitic Mesoderm ◽  
Posterior Displacement ◽  
Somite Formation ◽  
Gold Conjugate

Orthotopic grafts of wheat germ agglutinin-colloidal gold conjugate (WGA-gold) labelled cells were used to demonstrate differences in the segmental fate of cells in the presomitic mesoderm of the early-somite-stage mouse embryos developing in vitro. Labelled cells in the anterior region of the presomitic mesoderm colonized the first three somites formed after grafting, while those grafted to the middle region of this tissue were found mostly in the 4th-7th newly formed somites. Labelled cells grafted to the posterior region were incorporated into somites whose somitomeres were not yet present in the presomitic mesoderm at the time of grafting. There was therefore an apparent posterior displacement of the grafted cells in the presomitic mesoderm. Colonization of somites by WGA-gold labelled cells was usually limited to two to three consecutive somites in the chimaera. The distribution of cells derived from a single graft to two somites was most likely due to the segregation of the labelled population when cells were allocated to adjacent meristic units during somite formation. Further spreading of the labelled cells to several somites in some cases was probably the result of a more extensive mixing of mesodermal cells among the somitomeres prior to somite segmentation.

The histogenetic capacity of tissues in the caudal end of the embryonic axis of the mouse

Development ◽  
1984 ◽  
Vol 82 (1) ◽  
pp. 253-266
Author(s):  
P. P. L. Tam
Keyword(s):  
Developmental Stages ◽  
Primitive Streak ◽  
Mouse Embryos ◽  
Embryonic Axis ◽  
Tail Bud ◽  
Germ Layers ◽  
Kidney Capsule ◽  
Caudal Region ◽  
Caudal Portion ◽  
Adult Body

The caudal end of the embryonic axis consists of the primitive streak and the tail bud. Small fragments of this caudal tissue were transplanted from mouse embryos of various developmental stages to the kidney capsule in order to test their histogenetic capacity. The variety of mature tissues obtained from these small fragments was similar to that obtained by grafting a larger caudal portion of the embryo. Initially, the grafted tissue broke up into loose masses of embryonic mesenchyme and this was later re-organized into more compact tissues and into cysts that were lined with various types of epithelia. After 14 days in the ectopic site, grafted tissues coming from embryos of the primitive-streak, the early-somite and the forelimb-bud stages differentiated into structures that has presumably originated from the three embryonic germ layers. Many of these structures were related to the caudal region of the adult body, such as the mid- and hindgut segments and urogenital derivatives. The histogenetic capacity for endodermal tissues and urogenital organs was lost when the grafted tissue consisted entirely of the tail bud of the hindlimb-bud-stage embryos. The behaviour of the caudal tissues suggested that (1) the primordia for the various parts of embryonic body were derived from a small progenitor population in the primitive streak and the tail bud, and (2) the histogenetic capacity of this population changed during development.

scholarly journals Patterns and potential drivers of intraspecific variability in the body elemental composition of a terrestrial consumer, the snowshoe hare (Lepus americanus)

2019 ◽  
Author(s):  
Matteo Rizzuto ◽  
Shawn J. Leroux ◽  
Eric Vander Wal ◽  
Yolanda F. Wiersma ◽  
Travis R. Heckford ◽  
...  
Keyword(s):  
Body Size ◽  
Chemical Composition ◽  
Intraspecific Variability ◽  
Lepus Americanus ◽  
The Body ◽  
Whole Body ◽  
Snowshoe Hare ◽  
Weak Relationship ◽  
Snowshoe Hares ◽  
P Content

AbstractIntraspecific variability in ecological traits is widespread in nature. Recent evidence, mostly from aquatic ecosystems, shows individuals differing at the most fundamental level, that of their chemical composition. Age, sex, or body size may be key drivers of intraspecific variability in the body concentrations of carbon (C), nitrogen (N), and phosphorus (P). However, we still have a rudimentary understanding of the patterns and drivers of intraspecific variability in chemical composition of terrestrial consumers, particularly vertebrates.Here, we investigate the whole-body chemical composition of snowshoe hare Lepus americanus, providing one of the few studies of patterns of stoichiometric variability and its potential drivers for a terrestrial vertebrate. Based on snowshoe hare ecology, we expected higher P and N concentrations in females, as well as in larger and older individuals.We obtained whole-body C, N, and P concentrations and C:N, C:P, N:P ratios from a sample of 50 snowshoe hares. We then used general linear models to test for evidence of a relationship between age, sex, or body size and stoichiometric variability in hares.We found considerable variation in the C, N, and P concentrations and elemental ratios within our sample. Contrary to our predictions, we found evidence of N content decreasing with age. As expected, we found evidence of P content increasing with body size. As well, we found no support for a relationship between sex and N or P content, nor for variability in C content and any of our predictor variables.Despite finding considerable stoichiometric variability in our sample, we found no substantial support for age, sex, or body size to relate to this variation. The weak relationship between body N concentration and age may suggest varying nutritional requirements of individuals at different ages. Conversely, P’s weak relationship to body size appears in line with recent evidence of the potential importance of P in terrestrial systems. Snowshoe hares are a keystone herbivore in the boreal forest of North America. The substantial stoichiometric variability we find in our sample could have important implications for nutrient dynamics in both boreal and adjacent ecosystems.

scholarly journals Geminin Orchestrates Somite Formation by Regulating Fgf8 and Notch Signaling

2018 ◽  
Vol 2018 ◽  
pp. 1-13
Author(s):  
Wei Huang ◽  
Yu Zhang ◽  
Kang Cao ◽  
Lingfei Luo ◽  
Sizhou Huang
Keyword(s):  
Notch Signaling ◽  
Signaling Pathways ◽  
Critical Factor ◽  
Loss Of Function ◽  
Presomitic Mesoderm ◽  
Tail Bud ◽  
Notch Activity ◽  
Somite Formation ◽  
First Time

During somitogenesis, Fgf8 maintains the predifferentiation stage of presomitic mesoderm (PSM) cells and its retraction gives a cue for somite formation. Delta/Notch initiates the expression of oscillation genes in the tail bud and subsequently contributes to somite formation in a periodic way. Whether there exists a critical factor coordinating Fgf8 and Notch signaling pathways is largely unknown. Here, we demonstrate that the loss of function of geminin gave rise to narrower somites as a result of derepressed Fgf8 gradient in the PSM and tail bud. Furthermore, in geminin morphants, the somite boundary could not form properly but the oscillation of cyclic genes was normal, displaying the blurry somitic boundary and disturbed somite polarity along the AP axis. In mechanism, these manifestations were mediated by the disrupted association of the geminin/Brg1 complex with intron 3 of mib1. The latter interaction was found to positively regulate mib1 transcription, Notch activity, and sequential somite segmentation during somitogenesis. In addition, geminin was also shown to regulate the expression of deltaD in mib1-independent way. Collectively, our data for the first time demonstrate that geminin regulates Fgf8 and Notch signaling to regulate somite segmentation during somitogenesis.

Homoeobox gene Hox-1.5 expression in mouse embryos: earliest detection by in situ hybridization is during gastrulation

Development ◽  
1987 ◽  
Vol 101 (1) ◽  
pp. 51-60 ◽  
Author(s):  
S.J. Gaunt
Keyword(s):  
Nervous System ◽  
In Situ Hybridization ◽  
Mouse Embryos ◽  
The Body ◽  
Body Axis ◽  
Hybridization Technique ◽  
Newborn Mice ◽  
Neural Ectoderm ◽  
Somitic Mesoderm

We showed earlier (Gaunt, Miller, Powell & Duboule, 1986) that the mouse homoeobox gene Hox-1.5 is expressed in posterior ectoderm and mesoderm of 7 1/2- and 7 3/4-day embryos, and in the 9 1/2-day nervous system posterior to a discrete boundary within the hindbrain. In further in situ hybridization experiments, it is now shown that restriction of Hox-1.5 expression to the posterior regions of the embryo can be detected at stages of development between 7 1/2 and 9 1/2 days. During this period, the intensity of transcription in presomitic and somitic mesoderm declines relative to that in the overlying neural ectoderm, and the transcription boundary within the presumptive hindbrain region sharpens. Hox-1.5 expression posterior to the hindbrain boundary is detected in the 10 1/2- and 12 1/2-day embryo, but this is no longer found in newborn mice. Embryos of ages 3 1/2, 6 1/2 and 7 1/4 days showed no evidence of Hox-1.5 transcripts. It is concluded that embryos undergoing gastrulation (at 7 1/2 days) are the earliest stage at which Hox-1.5 transcripts can be detected by the in situ hybridization technique. In discussion, it is shown how this lies within the period of development during which tissues become determined along the anteroposterior axis of the mouse. Since there may be anterior-to-posterior variation in the time of determination along the body axis, it is suggested that homoeobox genes expressed more posteriorly, such as Hox-3 (Awgulewitsch et al. 1986), might start expression at times later in development.

scholarly journals β-Catenin and canonical Wnts control two separate pattern formation systems in Hydra: Insights from mathematical modelling

2021 ◽  
Author(s):  
Moritz Mercker ◽  
Tobias Lengfeld ◽  
Stefanie Höger ◽  
Anja Tursch ◽  
Mark Lommel ◽  
...  
Keyword(s):  
Pattern Formation ◽  
Wnt Signaling ◽  
De Novo ◽  
The Body ◽  
Whole Body ◽  
Small Scale ◽  
Axis Formation ◽  
Canonical Wnt Signaling ◽  
Canonical Wnt ◽  
Formation Systems

AbstractFormation of the body axes and the subsequent formation of the apical termini are two fundamental steps during animal development. In Hydra, nuclear β-Catenin and canonical HyWnt3 were identified as major players active in both processes. Based on molecular knowledge of canonical Wnt signaling directly linking nuclear β-Catenin and HyWnt3 activity, it was frequently assumed that de novo axis formation and the head formation were part of the same pattern formation system. In this work, combining new model simulations with available experimental results, we demonstrate that nuclear β-Catenin and HyWnt3 most likely contribute to two separate de novo pattern formation systems in Hydra, organizing development and differentiation on two different spatial scales. In particular, our results suggest that the nuclear β-Catenin acts on the scale of the whole body, controlling axis formation, whereas canonical HyWnt3 signaling is involved in a downstream pathway responsible for small-scale patterning of the head. Consequently, also in other animals where axis formation was ascribed to canonical Wnt signaling, the underlying mechanisms may be more complex than previously assumed.

Expression domains of a zebrafish homologue of the Drosophila pair-rule gene hairy correspond to primordia of alternating somites

Development ◽  
1996 ◽  
Vol 122 (7) ◽  
pp. 2071-2078 ◽  
Author(s):  
M. Muller ◽  
E. Weizsacker ◽  
J.A. Campos-Ortega
Keyword(s):  
Expression Pattern ◽  
Bhlh Protein ◽  
Presomitic Mesoderm ◽  
Tail Bud ◽  
Expression Domain ◽  
Somite Formation ◽  
Pair Rule Gene ◽  
Pair Rule ◽  
Time Point

her1 is a zebrafish cDNA encoding a bHLH protein with all features characteristic of members of the Drosophila HAIRY-E(SPL) family. During late gastrulation stages, her1 is expressed in the epibolic margin and in two distinct transverse bands of hypoblastic cells behind the epibolic front. After completion of epiboly, this pattern persists essentially unchanged through postgastrulation stages; the marginal domain is incorporated in the tail bud and, depending on the time point, either two or three paired bands of expressing cells are present within the paraxial presomitic mesoderm separated by regions devoid of transcripts. Labelling of cells within the her1 expression domains with fluorescein-dextran shows that the cells in the epibolic margin and the tail bud are not allocated to particular somites. However, allocation of cells to somites occurs between the marginal expression domain and the first expression band, anterior to it. Moreover, the her1 bands, and the intervening non-expressing zones, each represents the primordium of a somite. This expression pattern is highly reminiscent of that of Drosophila pair-rule genes. A possible participation of her1 in functions related to somite formation is discussed.

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