Approaches for Understanding Dynamic Cell Movements, Cell-Cell Interactions and Tissue Shaping During Embryogenesis of the Vertebrate Body Plan

1999 ◽  
Vol 5 (S2) ◽  
pp. 1078-1079
Author(s):  
G.C. Schoenwolf

The early vertebrate embryo develops a characteristic tube-within-a-tube body plan. This plan is realized through a series of cell movements and cell-cell interactions that collectively result in tissue shaping and the formation of the three-dimensional body plan. Tissue shaping is a highly choreographed process that is under the control of the organizer--a specialized region of the embryo that is both sufficient and required for formation of the body plan. Recent technical advances have greatly increased our understanding of the role of the organizer in vertebrate embryogenesis. Such advances include the use of new cellular, molecular, genetic, and embryological approaches.A hallmark of embryogenesis is its dynamic nature. Classically, embryos were studied in three major ways. 1) With morphological/descriptive analysis, initially involving histological procedures (stained whole mounts and serial sections cut in the three cardinal axes) and more recently electron microscopy.

2014 ◽  
Vol 11 (99) ◽  
pp. 20140631 ◽  
Author(s):  
Alexander Gord ◽  
William R. Holmes ◽  
Xing Dai ◽  
Qing Nie

Skin is a complex organ tasked with, among other functions, protecting the body from the outside world. Its outermost protective layer, the epidermis, is comprised of multiple cell layers that are derived from a single-layered ectoderm during development. Using a new stochastic, multi-scale computational modelling framework, the anisotropic subcellular element method, we investigate the role of cell morphology and biophysical cell–cell interactions in the formation of this layered structure. This three-dimensional framework describes interactions between collections of hundreds to thousands of cells and (i) accounts for intracellular structure and morphology, (ii) easily incorporates complex cell–cell interactions and (iii) can be efficiently implemented on parallel architectures. We use this approach to construct a model of the developing epidermis that accounts for the internal polarity of ectodermal cells and their columnar morphology. Using this model, we show that cell detachment, which has been previously suggested to have a role in this process, leads to unpredictable, randomized stratification and that this cannot be abrogated by adjustment of cell–cell adhesion interaction strength. Polarized distribution of cell adhesion proteins, motivated by epithelial polarization, can however eliminate this detachment, and in conjunction with asymmetric cell division lead to robust and predictable development.


Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 774
Author(s):  
Max Langer ◽  
Thomas Speck ◽  
Olga Speck

Although both the petiole and lamina of foliage leaves have been thoroughly studied, the transition zone between them has often been overlooked. We aimed to identify objectively measurable morphological and anatomical criteria for a generally valid definition of the petiole–lamina transition zone by comparing foliage leaves with various body plans (monocotyledons vs. dicotyledons) and spatial arrangements of petiole and lamina (two-dimensional vs. three-dimensional configurations). Cross-sectional geometry and tissue arrangement of petioles and transition zones were investigated via serial thin-sections and µCT. The changes in the cross-sectional geometries from the petiole to the transition zone and the course of the vascular bundles in the transition zone apparently depend on the spatial arrangement, while the arrangement of the vascular bundles in the petioles depends on the body plan. We found an exponential acropetal increase in the cross-sectional area and axial and polar second moments of area to be the defining characteristic of all transition zones studied, regardless of body plan or spatial arrangement. In conclusion, a variety of terms is used in the literature for describing the region between petiole and lamina. We prefer the term “petiole–lamina transition zone” to underline its three-dimensional nature and the integration of multiple gradients of geometry, shape, and size.


Author(s):  
Kiniwa Tsuyoshi ◽  
Kazuyo Moro

Abstract Group 2 innate lymphoid cells (ILC2s) are novel lymphocytes discovered in 2010. Unlike T or B cells, ILC2s are activated nonspecifically by environmental factors and produce various cytokines, thus playing a role in tissue homeostasis, diseases including allergic diseases, and parasite elimination. ILC2s were first reported as cells abundantly present in fat-associated lymphoid clusters in adipose tissue. However, subsequent studies revealed their presence in various tissues throughout the body, acting as key players in tissue-specific diseases. Recent histologic analyses revealed that ILC2s are concentrated in specific regions in tissues, such as the lamina propria and perivascular regions, with their function being controlled by the surrounding cells, such as epithelial cells and other immune cells, via cytokine and lipid production or by cell–cell interactions through surface molecules. Especially, some stromal cells are identified as the niche cells for ILC2s, both in the steady state and under inflammatory conditions, through the production of IL-33 or extracellular-matrix factors. Additionally, peripheral neurons reportedly co-localize with ILC2s and alter their function directly through neurotransmitters. These findings suggest that the different localizations or different cell–cell interactions might affect the function of ILC2s. Furthermore, generally, ILC2s are thought to be tissue-resident cells; however, they occasionally migrate to other tissues and perform a new role; this supports the importance of the microenvironment for their function. We summarize here the current understanding of how the microenvironment controls ILC2 localization and function with the aim of promoting the development of novel diagnostic and therapeutic methods.


2016 ◽  
Vol 13 (123) ◽  
pp. 20160613 ◽  
Author(s):  
Sebastian V. Hadjiantoniou ◽  
David Sean ◽  
Maxime Ignacio ◽  
Michel Godin ◽  
Gary W. Slater ◽  
...  

During embryogenesis, the spherical inner cell mass (ICM) proliferates in the confined environment of a blastocyst. Embryonic stem cells (ESCs) are derived from the ICM, and mimicking embryogenesis in vitro , mouse ESCs (mESCs) are often cultured in hanging droplets. This promotes the formation of a spheroid as the cells sediment and aggregate owing to increased physical confinement and cell–cell interactions. In contrast, mESCs form two-dimensional monolayers on flat substrates and it remains unclear if the difference in organization is owing to a lack of physical confinement or increased cell–substrate versus cell–cell interactions. Employing microfabricated substrates, we demonstrate that a single geometric degree of physical confinement on a surface can also initiate spherogenesis. Experiment and computation reveal that a balance between cell–cell and cell–substrate interactions finely controls the morphology and organization of mESC aggregates. Physical confinement is thus an important regulatory cue in the three-dimensional organization and morphogenesis of developing cells.


2012 ◽  
Vol 8 (11) ◽  
pp. 862-873 ◽  
Author(s):  
Ashneet Sachar ◽  
T. Amanda Strom ◽  
Symone San Miguel ◽  
Maria J. Serrano ◽  
Kathy K. H. Svoboda ◽  
...  

2014 ◽  
Vol 8 (4) ◽  
pp. 044105 ◽  
Author(s):  
K. Hockemeyer ◽  
C. Janetopoulos ◽  
A. Terekhov ◽  
W. Hofmeister ◽  
A. Vilgelm ◽  
...  

1998 ◽  
Vol 4 (S2) ◽  
pp. 1068-1069
Author(s):  
Ann-Marie Broome ◽  
Clarke F. Millette

Cell adhesion and cell adhesion molecules (CAMs) play a crucial role in testicular development and function. The seminiferous epithelium, the functional unit of the testis, represents a three dimensional architecture of supporting Sertoli cells (SC), and developing germ cells (GC). The seminiferous epithelium, therefore, must be receptive not only to individual cell growth and differentiation, but also to cell-cell interactions. Morphologically distinct cell-cell interactions occur between SC and GC and also between SC.[1] In general, these junctions can be categorized into three types: adhesive, occluding, and gap junctions. The orientation and function of these junctions are interaction dependent. For example, desmosome-like junctions (spot desmosomes) are found between SC and GC. These junctions are present in the basal and intermediate compartments of the testis and serve to translocate developing GC. SC-SC interactions, like the zonula occludens (tight junction), function as vectorial mediators, maintaining the blood-testis barrier and SC polarity.


Author(s):  
Eliot Goldfinger

There is a basic body plan common to most of the animals presented in this book. At its most obvious, they all have a head, a body, and four limbs. Most are four-legged and stand on all fours, and are described as having front limbs and rear limbs. The front limb is anatomically equivalent to the arm and hand in humans and primates, and the rear limb to the human lower limb. The animals in this book are surprisingly similar in many ways. The head is connected to the rib cage by the neck vertebrae and the rib cage is connected to the pelvis by the lumbar vertebrae. The two front limbs are connected to the rib cage, and the two rear limbs are connected to the pelvis. These units move in relation to one another, establishing the stance, or pose, of an animal. Animals differ primarily in the shape and relative proportions of these structural units, in the position of the wrist, heel, and toe bones when standing and walking, and by the number of their toes. An animal can be visualized as being constructed of a series of simplified, three-dimensional, somewhat geometric volumes (head, forearm, thigh). Each of these volumes has one dimension that is longer than the others. A line projected through the center of the mass of this volume on its longest dimension is called its axis (plural, axes). For the most part, especially in the limbs, these axes follow the skeleton, so that a line drawn through the long dimension of a bone is on, or close to, the axis of the volume of that region (for example, the position of the radius is close to the axis of the forearm). One of the more confusing regions of the body is the volume of the upper arm. The humerus (upper arm bone) is mostly deeply buried in muscle, and lies toward the front of this muscle mass, with the massive triceps muscle located at its rear.


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