scholarly journals Structural and Functional Relations between the Connective Tissue and Epithelium of Enamel Organ and their Role during Enamel Maturation

2021 ◽  
Author(s):  
Anas F Mahdee ◽  
Ahmed H Ali ◽  
James I Gillespie
Keyword(s):  
Connective Tissue ◽  
Membrane Surface ◽  
Cellular Heterogeneity ◽  
Enamel Organ ◽  
Cellular Interactions ◽  
Functional Relations ◽  
Ion Transportation ◽  
Immunohistochemical Techniques ◽  
Secondary Antibodies ◽  
Cx 43

Abstract The morphological and possible functional interactions between the connective tissue and epithelial elements of enamel organ were examined during the maturation phase, using immunohistochemical techniques. Decalcified mandibular sections (10µm) including incisors from Wistar rats ages 10–12 weeks were used. Sections were incubated with one or two primary antibodies targeting cell cytoskeleton (vimentin, α-actin, α-tubulin), dendritic marker (OX6), gap junctions (cx-43), enzymes (nitric-oxide synthase (nos1) and cyclooxygenase (cox1)), and ion transporters (Na+/H+ exchanger (NHE1) and Na+/Ca2+ exchanger (NCX)) for 24h, before incubation with the appropriate conjugated fluorescent secondary antibodies. Sections were then examined by fluorescence microscopy. Haematoxylin-eosin slides were also employed. Cellular heterogeneity and morphological modulations were identified within the epithelial and connective tissue elements of the enamel organ suggesting complex cellular interactions and indicating the use of enamel organ term to represent all these regions. Also, some ion transportation activity, and nos1 and cox1 signalling pathways have been identified, indicating intercellular communication between these regions. A hypothesis was suggested, to explain the morphological modulation of ameloblasts and papillary cells during enamel maturation aimed to increase the transporting membrane surface area to accomplish faster and bulker ion transportation to achieve controlled pH and to direct Ca2+ towards enamel. Connective tissue covering epithelial cells of the enamel organ showed morphological and physiological interaction during enamel maturation, suggesting new functional concepts.

scholarly journals The immunohistochemical presence and distribution of ghrelin, apelin and their receptors in dog ovaries

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Carolina Pirino ◽  
Margherita Maranesi ◽  
Angela Polisca ◽  
Alessandro Troisi ◽  
Cecilia Dall'Aglio
Keyword(s):  
Connective Tissue ◽  
Infectious Diseases ◽  
Positive Reaction ◽  
Corpora Lutea ◽  
Small Arteries ◽  
Luteal Cells ◽  
Peripheral Organs ◽  
Immunohistochemical Techniques

The activity of ghrelin, apelin and their receptors has been correlated to the control of some infectious diseases, besides the hypothesis of their role in the control of some peripheral organs, among which ovaries. The aim of the present work was to highlight the presence and distribution of ghrelin, apelin and cognate receptors in the ovaries of pregnant bitches, by means of immunohistochemical techniques. Apelin, its receptor and the receptor of ghrelin were highlighted in the corpora lutea, with a particular localization in the cytoplasm of some luteal cells. Instead, a positive reaction for ghrelin was evident in the walls of small arteries in the connective tissue. These results allowed us to hypothesize that these molecules intervene in the control of ovaries in pregnant bitches, suggesting autocrine/paracrine mechanisms of regulation.

The ultrastructure of the cardiac Purkinje strand in the dog: a morphometric analysis

1983 ◽  
Vol 217 (1207) ◽  
pp. 191-213 ◽  
Keyword(s):  
Electron Microscopy ◽  
Electrical Properties ◽  
Connective Tissue ◽  
Surface Area ◽  
Series Resistance ◽  
Membrane Surface ◽  
Light And Electron Microscopy ◽  
Total Surface Area ◽  
Membrane Surface Area ◽  
Extracellular Ions

Purkinje strands from both ventricles of adult mongrel dogs were excised, and electrical properties were studied by the voltage-clamp technique. The strands were then examined with light and electron microscopy and structural properties were analysed by morphometric techniques. The canine Purkinje strand contains (by volume) about 28% myocyte and 55% dense outer connective tissue. The remainder of the volume is taken up by the inner shell of loosely packed connective tissue within 10 μm of a myocyte membrane. These volume fractions vary considerably from one strand to another. Clefts less than 10 μm wide occupy 18% of the myocyte volume and clefts less than 1 μm wide occupy 1%. The membrane surface area of the myocytes can be divided into three categories by reference to the size of the adjacent cleft. About 47.8% of the membrane surface area faces clefts wider than 1 μm, another 22.2% faces clefts between 0.1 and 1 μm wide, and the final 30% faces clefts less than 0.1 μm wide. The surface area facing the narrowest clefts (less than 0.1 μm wide) is divided between nexuses 3%, desmosomes 10%, and unspecialized membrane 17% (each figure is expressed as a percentage of the total surface area of myocyte membrane). The canine Purkinje strand has a more favourable anatomy than the sheep Purkinje strand for most physiological experiments. We expect that the complicating effects of series resistance and change in the concentration of extracellular ions will be much smaller than in sheep strands, but still not negligible.

scholarly journals Single-cell analysis of the cellular heterogeneity and interactions in the injured mouse spinal cord

2021 ◽  
Vol 218 (8) ◽  
Author(s):  
Lindsay M. Milich ◽  
James S. Choi ◽  
Christine Ryan ◽  
Susana R. Cerqueira ◽  
Sofia Benavides ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Single Cell ◽  
Single Cell Analysis ◽  
Healing Process ◽  
Cellular Heterogeneity ◽  
Wound Healing Process ◽  
Cellular Interactions ◽  
Mouse Spinal Cord ◽  
Cord Injury

The wound healing process that occurs after spinal cord injury is critical for maintaining tissue homeostasis and limiting tissue damage, but eventually results in a scar-like environment that is not conducive to regeneration and repair. A better understanding of this dichotomy is critical to developing effective therapeutics that target the appropriate pathobiology, but a major challenge has been the large cellular heterogeneity that results in immensely complex cellular interactions. In this study, we used single-cell RNA sequencing to assess virtually all cell types that comprise the mouse spinal cord injury site. In addition to discovering novel subpopulations, we used expression values of receptor–ligand pairs to identify signaling pathways that are predicted to regulate specific cellular interactions during angiogenesis, gliosis, and fibrosis. Our dataset is a valuable resource that provides novel mechanistic insight into the pathobiology of not only spinal cord injury but also other traumatic disorders of the CNS.

Evaluation of biocompatibility of an experimental membrane for glucose sensors: the results of a prospective experimental controlled preclinical study involving laboratory animals

2017 ◽  
Vol 63 (4) ◽  
pp. 219-226 ◽  
Author(s):  
Yaroslav M. Stanishevskiy ◽  
Nadezhda P. Sachivkina ◽  
Yuriy V. Tarasov ◽  
Yury I. Philippov ◽  
Sergey A. Sokolov ◽  
...  
Keyword(s):  
Connective Tissue ◽  
Membrane Surface ◽  
Glucose Sensors ◽  
Laboratory Animals ◽  
Skin Reactions ◽  
Inflammatory Reactions ◽  
Connective Tissue Capsule ◽  
Coated Membranes ◽  
Coated Membrane ◽  
Tissue Capsule

An increase in the accuracy of monitoring of glucose concentration indicators and an increase in the running time of glucose sensors are promising directions in the field of diabetology. One of the ways to extend the lifetime of a sensor is its complete implantation excluding direct communication with the skin surface. For effective long-term functioning in the patient’s body, the surface of an implantable sensor should be highly biocompatibile: it should not induce allergic and inflammatory reactions as well as the demarcation reaction (formation of a dense connective tissue capsule). Earlier, a group of authors developed a glucose-permeable membrane and a biocompatible coating comprising a complex of nadroparin with transesterified polyethylene glycol and γ-aminopropyl triethoxysilane, which formed a protein repellent hydrogel on the membrane surface. Aims. To evaluate the biocompatibility of the experimental coated membrane implanted into laboratory animals. Methods. The experimental prospective controlled study involved 60 laboratory animals (Wistar albino rats). The animals were divided into 3 groups of 20 animals each. Animals of each group were implanted with the standard, or experimental, or experimental coated membrane. After implantation, the skin condition in the implantation area was visually assessed for 90 days. After 90 days, the tissue condition around the implant was evaluated histologically. Results. No serious allergic or inflammatory reactions in the implantation area were detected in all three groups of animals within 90 days of the follow-up period. In the case of the experimental coated membrane, a significantly low score was graded based on visual assessment of the skin reactions. In the histological analysis, the tissue condition in the implantation area of the coated membranes was characterized by significantly lower density of a connective tissue capsule and the presence of vascularization areas at the contact between of the membrane surface and the surrounding tissue. Conclusion. In experimental animals, the tested coating significantly inhibits formation of a connective tissue capsule around the implant and reduces the intensity of skin reactions after implantation. Further clinical studies of coated membranes in humans are required to verify their biocompatibility.

Ion transporters in secretory and cyclically modulating ameloblasts: a new hypothesis for cellular control of preeruptive enamel maturation

2010 ◽  
Vol 299 (6) ◽  
pp. C1299-C1307 ◽  
Author(s):  
Kaj Josephsen ◽  
Yoshiro Takano ◽  
Sebastian Frische ◽  
Jeppe Praetorius ◽  
Søren Nielsen ◽  
...  
Keyword(s):  
Connexin 43 ◽  
Cell Layer ◽  
Enamel Surface ◽  
Enamel Organ ◽  
Maturation Stage ◽  
Proton Pumps ◽  
Enamel Matrix Proteins ◽  
Cx 43 ◽  
Hydroxyapatite Crystals ◽  
Ph Fluctuations

Mature enamel consists of densely packed and highly organized large hydroxyapatite crystals. The molecular machinery responsible for the formation of fully matured enamel is poorly described but appears to involve oscillative pH changes at the enamel surface. We conducted an immunohistochemical investigation of selected transporters and related proteins in the multilayered rat incisor enamel organ. Connexin 43 (Cx-43) is found in papillary cells and ameloblasts, whereas Na+-K+-ATPase is heavily expressed during maturation in the papillary cell layer only. Given the distribution of Cx-43 channels and Na+-K+-ATPase, we suggest that ameloblasts and the papillary cell layer act as a functional syncytium. During enamel maturation ameloblasts undergo repetitive cycles of modulation between ruffle-ended (RA) and smooth-ended (SA) ameloblast morphologies. Carbonic anhydrase II and vacuolar H+-ATPase are expressed simultaneously at the beginning of the maturation stage in RA cells. The proton pumps are present in the ruffled border of RA and appear to be internalized during the SA stage. Both papillary cells and ameloblasts express plasma membrane acid/base transporters (AE2, NBC, and NHE1). AE2 and NHE1 change position relative to the enamel surface as localization of the tight junctions changes during ameloblast modulation cycles. We suggest that the concerted action of the papillary cell layer and the modulating ameloblasts regulates the enamel microenvironment, resulting in oscillating pH fluctuations. The pH fluctuations at the enamel surface may be required to keep intercrystalline spaces open in the surface layers of the enamel, enabling degraded enamel matrix proteins to be removed while hydroxyapatite crystals grow as a result of influx of calcium and phosphate ions.

scholarly journals Cellular interactions constrain tumor growth

2019 ◽  
Vol 116 (6) ◽  
pp. 1918-1923 ◽  
Author(s):  
Jeffrey West ◽  
Paul K. Newton
Keyword(s):  
Tumor Growth ◽  
Fitness Landscape ◽  
Cell Types ◽  
Cellular Level ◽  
Cellular Heterogeneity ◽  
Functional Coupling ◽  
Cellular Interactions ◽  
Macroscopic Tumor ◽  
Growth Laws ◽  
The Many

A tumor is made up of a heterogeneous collection of cell types, all competing on a fitness landscape mediated by microenvironmental conditions that dictate their interactions. Despite the fact that much is known about cell signaling, cellular cooperation, and the functional constraints that affect cellular behavior, the specifics of how these constraints (and the range over which they act) affect the macroscopic tumor growth laws that govern total volume, mass, and carrying capacity remain poorly understood. We develop a statistical mechanics approach that focuses on the total number of possible states each cell can occupy and show how different assumptions on correlations of these states give rise to the many different macroscopic tumor growth laws used in the literature. Although it is widely understood that molecular and cellular heterogeneity within a tumor is a driver of growth, here we emphasize that focusing on the functional coupling of states at the cellular level is what determines macroscopic growth characteristics.

scholarly journals TRANSPLANTATION OF TOOTH GERM ELEMENTS AND THE EXPERIMENTAL HETEROTOPIC FORMATION OF DENTIN AND ENAMEL

1934 ◽  
Vol 60 (2) ◽  
pp. 199-210 ◽  
Author(s):  
C. B. Huggins ◽  
H. R. McCarroll ◽  
A. A. Dahlberg
Keyword(s):  
Connective Tissue ◽  
Soft Tissues ◽  
Tooth Germ ◽  
Enamel Organ ◽  
Cylindrical Shape ◽  
Form And Function ◽  
Tissue Space ◽  
Pearl Formation ◽  
And Function ◽  
Connective Tissue Space

The formation of dentin and enamel in the abdominal wall in young pups was achieved by transplantation of the soft tissues of the developing tooth germ. An interesting finding was the cytomorphosis of the epithelium of the enamel organ. When this was transplanted so that the ameloblasts were in contact with the odontoblasts the cylindrical character of the epithelial cells was preserved and enamel was produced; otherwise the cylindrical shape of these cells was lost and a stratified epithelium resulted, resembling the gingival and certain tumors (the adamantinoma) of the jaw and related structures. This degenerated epithelium did not produce enamel and had an important characteristic of not forming cysts in a closed connective tissue space, instead forming islands and cords of cells with epithelial pearl formation. Thus the influence of mesodermic connective tissue derivatives on the form and function of epithelium is presented. The odonto-blasts were found capable of survival as such and readily formed new dentin in transplantation; the stellate cells of the pulp were inert from the standpoint of inducing calcification.

THROMBIN-SPECIFIC SITESOF FIBRINOGEN IN SMALL CELL CARCINOMA OF THE LUNG

1987 ◽  
Author(s):  
L Zacharski ◽  
V Memoli ◽  
S Rousseau
Keyword(s):  
Connective Tissue ◽  
Randomized Clinical Trials ◽  
Treatment Strategies ◽  
Coagulation Factor ◽  
Small Cell ◽  
Tumor Type ◽  
Human Fibrinogen ◽  
Previous Demonstration ◽  
Immunohistochemical Techniques ◽  
Connective Tissue Stroma

Thrombin-generated cleavage sites of human fibrinogen have been identified within the connective tissue stroma adjacent to viable tumor cells in fresh frozen sections of small cell carcinomaof the lung (SCCL) by means of immunohistochemical techniques using mouse monoclonal antibodies (designated alpha and beta) to the N-terminal peptides of the fibrinogen alpha and beta chains(provided by G. Matsueda and E. Haber).Specific connective tissue staining with antibody alpha was diffuse while staining with antibody beta was linear and focal. These results indicate thatthrombin is generated in situ in this tumor type. Previous demonstration of an initiator of coagulation together with coagulation factor intermediates associated with viable SCCL tumor cellsin situ(Cancer Res. 43:3963, 1983; Blood 66 (Suppl.1):329, 1985) is consistent with the hypothesis that the tumorcells themselves are responsible for the local thrombin generation. Because favorable effects of anticoagulant therapy with warfarin in SCCL have been demonstrated previouslyin two randomized clinical trials (J.A.M.A. 145:831, 1981; Proc. Am.Soc. Clin. Oncol. 4:191,1985), we postulate that local tumor cell-induced thrombin formation may contributeto self-regulated progression of SCCL through formation of a supportive, fibrin-rich connective tissue stroma (N. Engl. J. Med. 315:1650, 1986) and/or stimulation of cell proliferation (e.g. E.M.B.0. J. 4: 2927,1985; Proc. Natl. Acad. Sci. U.S.A. 83:976, 1986). These results suggest novel treatment strategies for this particular tumor type and justify efforts to identify other tumortypes in which similarmechanisms exist.

Evidence against a significant role for mast cells in blastocyst implantation in the rat and mouse

1996 ◽  
Vol 8 (8) ◽  
pp. 1157 ◽  
Author(s):  
LA Salamonsen ◽  
M Jeziorska ◽  
GF Newlands ◽  
SK Dey ◽  
DE Woolley
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Connective Tissue ◽  
Tissue Type ◽  
Mast Cell Protease ◽  
Murid Rodents ◽  
Blastocyst Implantation ◽  
Implantation Sites ◽  
Immunohistochemical Techniques ◽  
Rats And Mice

Rats were treated with the highly potent stabilizer of mast cells, FPL 55618, before and during the first seven days of pregnancy to establish whether stabilization of mast cells resulted in impaired blastocyst implantation. There was no significant reduction in either the number of ovulations or the number of implantation sites in treated rats compared with controls; 11 of 15 treated rats were pregnant compared with 5 of 6 control rats. The distribution of mast cells was examined in uterine tissues, implantation sites and interimplantation sites in both rats and mice using highly sensitive immunohistochemical techniques. Virtually all of the mast cells in rat uterine tissue stained for rat mast cell protease-I (RMCP-I; connective tissue type), whereas few stained for RMCP-II (mucosal type). Most of the mast cells were present in the myometrium with very sparse distribution in the endometrium and there were no differences in numbers of mast cells between implantation and inter-implantation sites on Day 7 of pregnancy. In tissue sections of mouse uteri sampled from Day 1 to Day 8 of pregnancy there were virtually no mast cells in the endometrium or deciduum adjacent to implantation sites. Mouse uterine mast cells also stained predominantly for the connective tissue-type mast cell protease MMCP-4, the murine equivalent of RMCP-I. Thus, mast cells and their products appear to play little, if any, role in blastocyst implantation in murid rodents. Since mast cells are a prominent feature of human endometrium, this study emphasizes the important consideration of species differences when choosing animal models for implantation studies.

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