scholarly journals The absence of muscle segment homeobox 2 leads to the pyroptosis of ameloblasts by inducing squamous epithelial hyperplasia in the enamel organ

2021 ◽  
Author(s):  
Juanjuan Zhang ◽  
Ying Xu ◽  
Ying Zhao ◽  
Jingkun Bai ◽  
Mengge Xu ◽  
...  
Keyword(s):  
Enamel Organ ◽  
Epithelial Hyperplasia

Electron Microscopic Study of the Epithelium of the Seminal Vesicle of Aging Rats

1974 ◽  
Vol 32 ◽  
pp. 138-139
Author(s):  
V. F. Allison ◽  
G. C. Fink ◽  
G. W. Cearley
Keyword(s):  
Cell Growth ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Seminal Vesicle ◽  
Seminal Vesicles ◽  
Epithelial Layer ◽  
Epithelial Hyperplasia ◽  
Electron Microscopic ◽  
Aging Rats ◽  
Pseudostratified Epithelium

It is well known that epithelial hyperplasia (benign hypertrophy) is common in the aging prostate of dogs and man. In contrast, little evidence is available for abnormal epithelial cell growth in seminal vesicles of aging animals. Recently, enlarged seminal vesicles were reported in senescent mice, however, that enlargement resulted from increased storage of secretion in the lumen and occurred concomitant to epithelial hypoplasia in that species.The present study is concerned with electron microscopic observations of changes occurring in the pseudostratified epithelium of the seminal vescles of aging rats. Special attention is given to certain non-epithelial cells which have entered the epithelial layer.

Autoradiography of Incorporated Leucine-H3 in the Enamel Matrix and Enamel Organ of the Upper Incisor of the Rat

1964 ◽  
Vol 04 (02) ◽  
pp. 186-192
Author(s):  
Leonel Costacurta
Keyword(s):  
Amino Acid ◽  
Blood Vessels ◽  
Tooth Germ ◽  
Longitudinal Section ◽  
Equal Length ◽  
Enamel Organ ◽  
Enamel Matrix ◽  
Distal Extremity ◽  
Old Rats ◽  
Thin Band

SummaryDental germs of the upper incisors of six-days old rats were studied for the uptake of leucine-H3 by different layers of the enamel organ in correlation to the various stages of the development of enamel.The longitudinal section of the tooth germ was divided into 15 zones of about equal length in order to facilitate the description and interpretation of results. Autoradiographic images of the histologic preparations from rats sacrificed 30 minutes, 1 hour, 1 day and 3 days after the injection were made. The strongest reactions were observed in dental germs of rats sacrificed 1 hour, and particularly one day, after the leucine-H3 injection.The uptake of this compound by the enamel matrix increases progressively up to the young enamel and then decreases to the distal extremity; the greatest quantity of this labeled amino-acid was observed in the primary and young enamel. The reactions were present in the transitional enamel only along a thin band close to the dentine-enamel junction.In the enamel organ leucine-H3 incorporation was greatest in the three layers, the zones corresponding to primary and young enamel. In zones corresponding to transitional enamel, the inner epithelium showed a small quantity, and the stellate reticulum a blackening only in its superficial part, were the blood vessels reach the enamel organ.

CAPILLARY PATTERN OF THE THYROID GLAND IN THE RAT IN FUNCTIONAL BLOCK

1962 ◽  
Vol 40 (3) ◽  
pp. 441-450 ◽  
Author(s):  
K. E. Arosenius ◽  
G. Nylander
Keyword(s):  
Thyroid Gland ◽  
Control Group ◽  
List Type ◽  
Epithelial Hyperplasia ◽  
Intact Control ◽  
Functional Block ◽  
Propyl Thiouracil

ABSTRACT The capillary pattern of the thyroid gland was studied in the rat: one group had undergone hemithyroidectomy, one was treated with propyl thiouracil, and one subjected to both these experimental measures. Histological and microangiographic observations were compared with those in an intact control group. Epithelial hyperplasia and other morphological signs of activity were seen to a moderate extent in the hemithyroidectomized group, were marked in the rats treated with thiouracil, and most marked in the group subjected to both thiouracil medication and hemithyroidectomy. The appearances of the interfollicular capillaries showed no perceptible changes in the group subjected solely to hemithyroidectomy. Changes of the interfollicular capillaries were marked in all the animals treated with propyl thiouracil. In the group only treated with propyl thiouracil, the capillaries were dilated to sinusoid-like blood pools in limited segments between which the capillaries were of normal width. In the group subjected to both hemithyroidectomy and propyl thiouracil treatment the interfollicular capillaries were dilated throughout their course. The significance of these morphological and microangiographic observations is discussed.

scholarly journals Role of Innate Inflammation in the Regulation of Tissue Remodeling during Tooth Eruption

2021 ◽  
Vol 9 (1) ◽  
pp. 7
Author(s):  
Yusuke Makino ◽  
Kaoru Fujikawa ◽  
Miwako Matsuki-Fukushima ◽  
Satoshi Inoue ◽  
Masanori Nakamura
Keyword(s):  
Bacterial Infections ◽  
Tooth Movement ◽  
Tooth Eruption ◽  
Intercellular Adhesion Molecule ◽  
Enamel Organ ◽  
Pcr Analysis ◽  
Maturation Stage ◽  
Oral Epithelium ◽  
Rt Pcr ◽  
Inflammatory Reactions

Tooth eruption is characterized by a coordinated complex cascade of cellular and molecular events that promote tooth movement through the eruptive pathway. During tooth eruption, the stratum intermedium structurally changes to the papillary layer with tooth organ development. We previously reported intercellular adhesion molecule-1 (ICAM-1) expression on the papillary layer, which is the origin of the ICAM-1-positive junctional epithelium. ICAM-1 expression is induced by proinflammatory cytokines, including interleukin-1 and tumor necrosis factor. Inflammatory reactions induce tissue degradation. Therefore, this study aimed to examine whether inflammatory reactions are involved in tooth eruption. Reverse transcription-polymerase chain reaction (RT-PCR) analysis revealed sequential expression of hypoxia-induced factor-1α, interleukin-1β, and chemotactic factors, including keratinocyte-derived chemokine (KC) and macrophage inflammatory protein-2 (MIP-2), during tooth eruption. Consistent with the RT-PCR results, immunohistochemical analysis revealed KC and MIP-2 expression in the papillary layer cells of the enamel organ from the ameloblast maturation stage. Moreover, there was massive macrophage and neutrophil infiltration in the connective tissue between the tooth organ and oral epithelium during tooth eruption. These findings suggest that inflammatory reactions might be involved in the degradation of tissue overlying the tooth organ. Further, these reactions might be induced by hypoxia in the tissue overlying the tooth organ, which results from decreased capillaries in the tissue. Our findings indicate that bacterial infections are not associated with the eruption process. Therefore, tooth eruption might be regulated by innate inflammatory mechanisms.

scholarly journals Persistent rhinitis and epithelial remodeling induced by cyclic ozone exposure in the nasal airways of infant monkeys

2011 ◽  
Vol 300 (2) ◽  
pp. L242-L254 ◽  
Author(s):  
Stephan A. Carey ◽  
Carol A. Ballinger ◽  
Charles G. Plopper ◽  
Ruth J. McDonald ◽  
Alfred A. Bartolucci ◽  
...  
Keyword(s):  
Rhesus Macaques ◽  
Squamous Metaplasia ◽  
Differential Susceptibility ◽  
Respiratory Illness ◽  
Air Pollutant ◽  
Ozone Exposure ◽  
Nasal Passage ◽  
Epithelial Hyperplasia ◽  
Nasal Airways ◽  
Airway Injury

Children chronically exposed to high levels of ozone (O3), the principal oxidant pollutant in photochemical smog, are more vulnerable to respiratory illness and infections. The specific factors underlying this differential susceptibility are unknown but may be related to air pollutant-induced nasal alterations during postnatal development that impair the normal physiological functions (e.g., filtration and mucociliary clearance) serving to protect the more distal airways from inhaled xenobiotics. In adult animal models, chronic ozone exposure is associated with adaptations leading to a decrease in airway injury. The purpose of our study was to determine whether cyclic ozone exposure induces persistent morphological and biochemical effects on the developing nasal airways of infant monkeys early in life. Infant (180-day-old) rhesus macaques were exposed to 5 consecutive days of O3 [0.5 parts per million (ppm), 8 h/day; “1-cycle”] or filtered air (FA) or 11 biweekly cycles of O3 (FA days 1– 9; 0.5 ppm, 8 h/day on days 10– 14; “11-cycle”). The left nasal passage was processed for light microscopy and morphometric analysis. Mucosal samples from the right nasal passage were processed for GSH, GSSG, ascorbate (AH2), and uric acid (UA) concentration. Eleven-cycle O3 induced persistent rhinitis, squamous metaplasia, and epithelial hyperplasia in the anterior nasal airways of infant monkeys, resulting in a 39% increase in the numeric density of epithelial cells. Eleven-cycle O3 also induced a 65% increase in GSH concentrations at this site. The persistence of epithelial hyperplasia was positively correlated with changes in GSH. These results indicate that early life ozone exposure causes persistent nasal epithelial alterations in infant monkeys and provide a potential mechanism for the increased susceptibility to respiratory illness exhibited by children in polluted environments.

scholarly journals Plutonium-induced Proliferative Lesions and Pulmonary Epithelial Neoplasms in the Rat: Immunohistochemical and Ultrastructural Evidence for Their Origin from Type II Pneumocytes

1994 ◽  
Vol 31 (3) ◽  
pp. 366-374 ◽  
Author(s):  
R. A. Herbert ◽  
B. S. Stegelmeier ◽  
N. A. Gillett ◽  
A. H. Rebar ◽  
W. W. Carlton ◽  
...  
Keyword(s):  
Clara Cell ◽  
Normal Lung ◽  
Type Ii ◽  
Epithelial Hyperplasia ◽  
Cell Antigen ◽  
Alveolar Epithelial ◽  
Type Ii Pneumocytes ◽  
Epithelial Neoplasms ◽  
Epithelial Lesions ◽  
Surfactant Apoprotein

Immunohistochemistry and transmission electron microscopy were used to clarify the cellular origin for plutonium-239-induced pulmonary proliferative (preneoplastic) epithelial lesions and epithelial neoplasms in F344 rats. Examples of each histologic type of proliferative lesion and neoplasm were stained by the avidin-biotin complex immunoperoxidase method using antibodies to rat surfactant apoprotein and Clara cell antigen. Rat surfactant apoprotein immunostaining was detected in type II pneumocytes in sections of normal lung, in the cells of the proliferative lesions classified histologically as alveolar epithelial hyperplasia (51) and mixed foci (alveolar epithelial hyperplasia with fibrosis) (30), and in adenomas (2), adenocarcinomas (3), and adenosquamous carcinomas (2). With the exception of one adenosquamous carcinoma, Clara cell antigen immunostaining was not detected in any of the pulmonary lesions but was detected in nonciliated cuboidal epithelial (Clara) cells in normal bronchioles. The epithelial cells of the proliferative lesions and neoplasms had ultrastructural features consistent with type II pneumocytes, i.e., the presence of cytoplasmic lamellar and multivesicular bodies. The results of these studies indicate that the majority of plutonium-induced proliferative epithelial lesions and neoplasms in the rat originate from alveolar type II pneumocytes.

Relative Levels of mRNA Encoding Enamel Proteins in Enamel Organ Epithelia and Odontoblasts

2003 ◽  
Vol 82 (12) ◽  
pp. 982-986 ◽  
Author(s):  
T. Nagano ◽  
S. Oida ◽  
H. Ando ◽  
K. Gomi ◽  
T. Arai ◽  
...  
Keyword(s):  
Tooth Enamel ◽  
Structural Proteins ◽  
Enamel Organ ◽  
Maturation Stage ◽  
Mrna Levels ◽  
Rt Pcr ◽  
Enamel Protein ◽  
Enamel Proteins ◽  
Enamel Layer

Amelogenin, enamelin, sheathlin (ameloblastin/ amelin), enamelysin (MMP-20), and KLK4 (EMSP-1) are the major structural proteins and proteinases in developing tooth enamel. Recently, odontoblasts were reported to express amelogenin, the most abundant enamel protein. In this study, we hypothesized that odontoblasts express all enamel proteins and proteases, and we measured their relative mRNA levels in enamel organ epithelia and odontoblasts associated with porcine secretory- and maturation-stage enamel by RT-PCR, using a LightCycler instrument. The results showed that amelogenin mRNA in secretory-stage EOE is 320-fold higher than in odontoblasts beneath secretory-stage enamel, and over 20,000-fold higher than in odontoblasts under maturation-stage enamel. Similar results were obtained for enamelin and sheathlin. Enamelysin mRNA levels were equivalent in these two tissues, while KLK4 mRNA was higher in odontoblasts than in secretory-stage EOE. These results support the conclusion that odontoblasts are involved in the formation of the enamel layer adjacent to enamel-dentin junction.

Penetration of various molecular-weight proteins into the enamel organ and enamel of the rat incisor

1986 ◽  
Vol 31 (5) ◽  
pp. 287-296 ◽  
Author(s):  
M.D. McKee ◽  
B. Martineau-Doize ◽  
H. Warshawsky
Keyword(s):  
Molecular Weight ◽  
Enamel Organ ◽  
Rat Incisor

Matrix and Mineral Changes in Developing Enamel

1979 ◽  
Vol 58 (2_suppl) ◽  
pp. 871-882 ◽  
Author(s):  
C. Robinson ◽  
H.D. Briggs ◽  
P.J. Atkinson ◽  
J.A. Weatherell
Keyword(s):  
Mineral Content ◽  
Inorganic Ions ◽  
Organic Matrix ◽  
Small Samples ◽  
Enamel Organ ◽  
Enamel Matrix ◽  
Subsequent Loss ◽  
Matrix Components ◽  
Significant Concentration ◽  
Mineral Changes

An investigation of the changes taking place in the enamel and the enamel organ during enamel development has been carried out by analyzing small samples of tissue dissected from developing incisors of rat and bovine incisors. Observations showed that the synthesis of the enamel matrix and its subsequent loss were associated chiefly with a change in the major matrix components. This consisted of a selective loss of amelogenin components prior to secondary mineralization. Before this loss, some increase in the proportion of smaller molecular weight components suggested the possibility of limited breakdown. Even at the earliest stages examined, significant concentration of mineral ions was present. This increased steeply after most of the organic matrix had been removed. The Ca/P ratio of this mineral was constant throughout development. The concentration of minor inorganic ions (F, Mg and CO3) decreased as the tissue developed and a tendency was observed for certain ions (F, 32PO4) to penetrate and concentrate in the enamel, apparently as a consequence of the lost matrix being replaced by water, just prior to the steep increase in mineral content of the tissue.

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