scholarly journals Architecture of the Pancreatic Islets and Endocrine Cell Arrangement in the Embryonic Pancreas of the Grass Snake (Natrix natrix L.). Immunocytochemical Studies and 3D Reconstructions

2021 ◽  
Vol 22 (14) ◽  
pp. 7601
Author(s):  
Magdalena Kowalska ◽  
Weronika Rupik
Keyword(s):  
Endocrine Cells ◽  
Developmental Stages ◽  
Cell Types ◽  
Dorsal Pancreas ◽  
The Core ◽  
Embryonic Pancreas ◽  
Grass Snake ◽  
D Cells ◽  
Different Cell Types ◽  
Early Developmental

During the early developmental stages of grass snakes, within the differentiating pancreas, cords of endocrine cells are formed. They differentiate into agglomerates of large islets flanked throughout subsequent developmental stages by small groups of endocrine cells forming islets. The islets are located within the cephalic part of the dorsal pancreas. At the end of the embryonic period, the pancreatic islet agglomerates branch off, and as a result of their remodeling, surround the splenic “bulb”. The stage of pancreatic endocrine ring formation is the first step in formation of intrasplenic islets characteristics for the adult specimens of the grass snake. The arrangement of endocrine cells within islets changes during pancreas differentiation. Initially, the core of islets formed from B and D cells is surrounded by a cluster of A cells. Subsequently, A, B, and D endocrine cells are mixed throughout the islets. Before grass snake hatching, A and B endocrine cells are intermingled within the islets, but D cells are arranged centrally. Moreover, the pancreatic polypeptide (PP) cells are not found within the embryonic pancreas of the grass snake. Variation in the proportions of different cell types, depending on the part of the pancreas, may affect the islet function—a higher proportion of glucagon cells is beneficial for insulin secretion.

scholarly journals Core-shell bioprinting as a strategy to apply differentiation factors in a spatially defined manner inside osteochondral tissue substitutes

2021 ◽  
Author(s):  
David Kilian ◽  
Silvia Cometta ◽  
Anne Bernhardt ◽  
Rania Taymour ◽  
Jonas Golde ◽  
...  
Keyword(s):  
Binding Capacity ◽  
Close Contact ◽  
Release Kinetics ◽  
Cell Types ◽  
Core Shell ◽  
The Core ◽  
Differentiation Factors ◽  
Local Supply ◽  
Osteochondral Tissue ◽  
Different Cell Types

Abstract One of the key challenges in osteochondral tissue engineering is to define specified zones with varying material properties, cell types and biochemical factors supporting locally adjusted differentiation into the osteogenic and chondrogenic lineage, respectively. Herein, extrusion-based core-shell bioprinting is introduced as a potent tool allowing a spatially defined delivery of cell types and differentiation factors TGF-β3 and BMP-2 in separated compartments of hydrogel strands, and, therefore, a local supply of matching factors for chondrocytes and osteoblasts. Ink development was based on blends of alginate and methylcellulose, in combination with varying concentrations of the nanoclay Laponite whose high affinity binding capacity for various molecules was exploited. Release kinetics of model molecules was successfully tuned by Laponite addition. Core-shell bioprinting was proven to generate well-oriented compartments within one strand as monitored by optical coherence tomography in a non-invasive manner. Chondrocytes and osteoblasts were applied each in the shell while the respective differentiation factors (TGF-β3, BMP-2) were provided by a Laponite-supported core serving as central factor depot within the strand, allowing directed differentiation of cells in close contact to the core. Experiments with bi-zonal constructs, comprising an osteogenic and a chondrogenic zone, revealed that the local delivery of the factors from the core reduces effects of these factors on the cells in the other scaffold zone. These observations prove the general suitability of the suggested system for co-differentiation of different cell types within a zonal construct.

scholarly journals Efficiency of RNA Interference in the Mouse Hematopoietic System Varies between Cell Types and Developmental Stages

2005 ◽  
Vol 25 (10) ◽  
pp. 3896-3905 ◽  
Author(s):  
Philipp Oberdoerffer ◽  
Chryssa Kanellopoulou ◽  
Vigo Heissmeyer ◽  
Corinna Paeper ◽  
Christine Borowski ◽  
...  
Keyword(s):  
Rna Interference ◽  
Gene Targeting ◽  
Developmental Stages ◽  
Cell Types ◽  
Gene Inactivation ◽  
Loss Of Function ◽  
Homologous Genes ◽  
Family Gene ◽  
Interfering Rna ◽  
Different Cell Types

ABSTRACT RNA interference (RNAi) is a naturally occurring posttranscriptional gene-silencing mechanism that has been adapted as a genetic tool for loss-of-function studies of a variety of organisms. It is more widely applicable than classical gene targeting and allows for the simultaneous inactivation of several homologous genes with a single transgene. Recently, RNAi has been used for conditional and conventional gene inactivation in mice. Unlike gene targeting, RNAi is a dynamic process, and its efficiency may vary both between cell types and throughout development. Here we demonstrate that RNAi can be used to target three separately encoded isoforms of the bcl-2 family gene bfl-1/A1 in a conditional manner in mice. The extent of gene inactivation varies between different cell types and is least efficient in mature lymphocytes. Our data suggest that RNAi is affected by factors beyond small interfering RNA-mRNA stoichiometry.

scholarly journals Obtaining Oviparous Grass Snake, Natrix natrix (Serpentes, Colubridae), embryos at Early Developmental Stages by Caesarean Section

Zoodiversity ◽  
2021 ◽  
Vol 55 (3) ◽  
pp. 217-224
Author(s):  
H. V. Sheverdyukova ◽  
I. R. Merzlikin
Keyword(s):  
Caesarean Section ◽  
Developmental Stages ◽  
Significant Development ◽  
The Past ◽  
Reproductive Ability ◽  
Natrix Natrix ◽  
In The Wild ◽  
Grass Snake ◽  
Gravid Females ◽  
Early Developmental

There is a specific feature in the developmental biology of oviparous snakes: embryos in the eggs, which were just laid, have already undergone significant development. This fact makes it significantly complicated to obtain data on organs’ development at early stages of embryogenesis. In addition, the fertilization time and the duration of snake pregnancy in the wild are unknown. In order to obtain the embryos of an oviparous grass snake Natrix natrix (Linnaeus, 1758) at successive developmental stages with minimal harm to gravid females we used caesarean section. The past known experience of performing caesarean section in snakes and anesthesia in reptiles were used. All the embryos were taken from the upper oviduct of a female simultaneously; in this way we eliminated the influence of medications on embryos’ development. The described method is valuable when it is necessary to obtain snake embryos and to preserve the life of the female and, possibly,its reproductive ability.

scholarly journals THE ENDOCRINE CELLS IN THE EPITHELIUM OF THE GASTROINTESTINAL MUCOSA OF THE RAT

1969 ◽  
Vol 40 (3) ◽  
pp. 692-715 ◽  
Author(s):  
W. G. Forssmann ◽  
L. Orci ◽  
R. Pictet ◽  
A. E. Renold ◽  
C. Rouiller
Keyword(s):  
Gastrointestinal Tract ◽  
Morphological Study ◽  
Endocrine Cells ◽  
Cell Types ◽  
Endocrine Function ◽  
Cell Type ◽  
Gastrointestinal Mucosa ◽  
Type Iv ◽  
A Cells ◽  
D Cells

The authors of this study examine the question of whether the so-called enterochromaffin or argentaffin cells of the gastrointestinal tract should be considered as a single cell type. The systematic application of purely morphologic methods has led to the conclusion that the epithelium of the gastrointestinal mucosa comprises endocrine cells of several types. This conclusion is primarily based on the uneven and characteristic distribution of the various cell types along the intestinal tract, an observation precluding the interpretation that the different types correspond to diverse functional stages of the same cell. A specific endocrine function may be attributed to each of the given cell types recognized so far on account of their appearance and their localization in characteristic areas of the gastrointestinal tract. It is acknowledged, however, that a purely morphological study leaves room for doubt. The first cell type is probably responsible for the formation of 5-hydroxytryptamine. Cells of type II are morphologically comparable to the pancreatic A cells and may, therefore, be called intestinal A cells. Cell type III comprises intestinal D cells since their appearance corresponds to that of pancreatic D cells. Cell type IV might well be responsible for catecholamine production, whereas gastrin is in all probability produced in endocrine cell type V. As yet, the thorough morphological study of the gastrointestinal epithelium does not provide information as to additional distinct cellular sites of production of the several other hormones isolated from different parts of the gut.

TET enzymes, DNA demethylation and pluripotency

2019 ◽  
Vol 47 (3) ◽  
pp. 875-885 ◽  
Author(s):  
Samuel E. Ross ◽  
Ozren Bogdanovic
Keyword(s):  
Embryonic Stem ◽  
Cell Types ◽  
Dna Demethylation ◽  
Multiple Roles ◽  
Model Systems ◽  
Tet Proteins ◽  
Vertebrate Model ◽  
Tet Enzymes ◽  
Different Cell Types ◽  
Early Developmental

Abstract Ten-eleven translocation (TET) methylcytosine dioxygenases (TET1, TET2, TET3) actively cause demethylation of 5-methylcytosine (5mC) and produce and safeguard hypomethylation at key regulatory regions across the genome. This 5mC erasure is particularly important in pluripotent embryonic stem cells (ESCs) as they need to maintain self-renewal capabilities while retaining the potential to generate different cell types with diverse 5mC patterns. In this review, we discuss the multiple roles of TET proteins in mouse ESCs, and other vertebrate model systems, with a particular focus on TET functions in pluripotency, differentiation, and developmental DNA methylome reprogramming. Furthermore, we elaborate on the recently described non-catalytic roles of TET proteins in diverse biological contexts. Overall, TET proteins are multifunctional regulators that through both their catalytic and non-catalytic roles carry out myriad functions linked to early developmental processes.

Neurosecretory innervation of the pituitary of the eels anguilla and conger II. The structure and innervation of the pars distalis at different stages of the life-cycle

1966 ◽  
Vol 250 (768) ◽  
pp. 329-342 ◽  
Keyword(s):  
Life Cycle ◽  
Endocrine Cells ◽  
Functional Relationship ◽  
Cell Types ◽  
Intermediate Lobe ◽  
Special Importance ◽  
Pars Distalis ◽  
Distinct Cell ◽  
Different Cell Types ◽  
The Relationship

A number of distinct cell types may be recognized in the pituitary of the eel at the level of ultra-­structure by reason of the specificity of the size and electron-density of the granules they contain. The size of the granules and changes in the different cell types at different stages of the life-cycle permit a tentative identification in terms of function. The pars distalis of the eel pituitary receives the greater part of its innervation from the nucleus lateralis tuberis by Type B neurosecretory fibres (Knowles 1965 a ), which do not stain with the so-called neurosecretory stains, but which nevertheless contain elementary neurosecretory vesicles. Type A, or classical, neurosecretory innervation is also present and seems to be of special importance at certain stages of the life-cycle. The possible function of these two forms of neurosecretory inner­- vation is discussed. The relationship between the intrinsic endocrine cells of the pars distalis and their neurosecretory innervation is fundamentally similar, at the level of ultrastructure, to that of the neuro-intermediate lobe. There are no direct contacts between the neurosecretory fibres and the intrinsic endocrine cells, but the proximity of the fibre terminals ( ca. 2000 to 4000 A) to endocrine cells indicates a functional relationship between these two elements of the pituitary of the eel.

scholarly journals Diverse mechanisms regulate contractile ring assembly for cytokinesis in the two-cell C. elegans embryo

2022 ◽  
Author(s):  
Imge Ozugergin ◽  
Karina Mastronardi ◽  
Chris Law ◽  
Alisa Piekny
Keyword(s):  
Cell Types ◽  
Somatic Tissue ◽  
Ring Closure ◽  
Contractile Ring ◽  
C Elegans ◽  
Daughter Cells ◽  
The Core ◽  
Ring Assembly ◽  
Different Cell Types ◽  
Ring Position

Cytokinesis occurs at the end of mitosis due to the ingression of a contractile ring that cleaves the daughter cells. The core machinery regulating this crucial process is conserved among metazoans. Multiple pathways control ring assembly, but their contribution in different cell types is not known. We found that in the C. elegans embryo, AB and P1 cells fated to be somatic tissue and germline, respectively, have different cytokinesis kinetics supported by distinct myosin levels and organization. Through perturbation of RhoA or polarity regulators and the generation of tetraploid strains, we found that ring assembly is controlled by multiple fate-dependent factors that include myosin-levels, and mechanisms that respond to cell size. Active Ran coordinates ring position with the segregating chromatids in HeLa cells by forming an inverse gradient with importins that control the cortical recruitment of anillin. We found that the Ran pathway regulates anillin in AB cells, but functions differently in P1 cells. We propose that ring assembly delays in P1 cells caused by low myosin and Ran signaling coordinate the timing of ring closure with their somatic neighbours.

scholarly journals The Ran pathway uniquely regulates cytokinesis in cells with different fates in the early C. elegans embryo

2021 ◽  
Author(s):  
Imge Ozugergin ◽  
Karina Mastronardi ◽  
Chris Law ◽  
Alisa Piekny
Keyword(s):  
Cell Fate ◽  
Cell Types ◽  
Contractile Ring ◽  
C Elegans ◽  
Multiple Parameters ◽  
Daughter Cells ◽  
The Core ◽  
Cortical Patterning ◽  
Different Cell Types ◽  
In Cells

ABSTRACTCytokinesis occurs at the end of mitosis and occurs due to the ingression of a contractile ring that cleaves the daughter cells. This process is tightly controlled to prevent cell fate changes or aneuploidy, and the core machinery is highly conserved among metazoans. Multiple mechanisms regulate cytokinesis, but their requirement in different cell types is not known. Here, we show that differently fated AB and P1 cells in the early C. elegans embryo have unique cytokinesis kinetics supported by distinct levels and cortical patterning of myosin. Through perturbation of polarity regulators and the generation of stable tetraploid strains, we demonstrate that these differences depend on both cell fate and size. Additionally, these parameters could influence the Ran pathway, which coordinates the contractile ring with chromatin position, and controls cytokinesis differently in AB and P1 cells. Our findings demonstrate the need to consider multiple parameters when modeling ring kinetics.

scholarly journals Seven MADS-box Genes in Apple are Expressed in Different Parts of the Fruit

1999 ◽  
Vol 124 (1) ◽  
pp. 8-13 ◽  
Author(s):  
Jia-Long Yao ◽  
Yi-Hu Dong ◽  
Anders Kvarnheden ◽  
Bret Morris
Keyword(s):  
Developmental Stages ◽  
Expression Patterns ◽  
Mads Box ◽  
Mads Box Genes ◽  
Preferential Expression ◽  
The Core ◽  
Early Developmental ◽  
Dna Sequence Comparison ◽  
Different Parts

To study the role of MADS-box genes in developing apples (Malus ×domestica Borkh.), clones corresponding to seven different genes, MdMADS5 to MdMADS11, were isolated from a 2-day-old apple cDNA library. Through DNA sequence comparison, six genes were classified into the APETALA1 (AP1) group and one gene, MdMADS10, into the AGAMOUS (AG) group. Six of the genes, MdMADS5 to MdMADS10, were found to be preferentially expressed in fruit following pollination. These genes also showed differential expression patterns in core, cortex and skin of young fruit. For instance, MdMADS5, which is highly homologous to AP1, showed preferential expression in the cortex and skin tissues while MdMADS10, which is highly homologous to AGL11, showed exclusive expression in the core tissues. The gene MdMADS11 showed a similar expression level and pattern in flowers, fruit at several early developmental stages, and for different fruit tissues. The range of expression patterns suggests that the genes play different roles in apple development.

Study of the Molecular Architecture of Keratin Filaments by Electron Microscopy

1982 ◽  
Vol 40 ◽  
pp. 118-119
Author(s):  
U. Aebi ◽  
P. Rew ◽  
T.-T. Sun
Keyword(s):  
Electron Microscopy ◽  
Structural Organization ◽  
Cell Types ◽  
Structural Features ◽  
Molecular Architecture ◽  
The Past ◽  
Keratin Filaments ◽  
Different Types ◽  
10 Nm Filaments ◽  
Different Cell Types

Various types of intermediate-sized (10-nm) filaments have been found and described in many different cell types during the past few years. Despite the differences in the chemical composition among the different types of filaments, they all yield common structural features: they are usually up to several microns long and have a diameter of 7 to 10 nm; there is evidence that they are made of several 2 to 3.5 nm wide protofilaments which are helically wound around each other; the secondary structure of the polypeptides constituting the filaments is rich in ∞-helix. However a detailed description of their structural organization is lacking to date.

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