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Epithelium

About: Epithelium is a research topic. Over the lifetime, 12981 publications have been published within this topic receiving 558355 citations. The topic is also known as: epithelia & epithelial tissue.


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01 Jan 1962
TL;DR: The cell Epithelium Glands and secretion Blood Connective tissue proper Adipose tissue Cartilage Bone Bone marrow and blood cell formation Muscular tissue The nervous tissue, Jay B. Angevine
Abstract: The cell Epithelium Glands and secretion Blood Connective tissue proper Adipose tissue Cartilage Bone Bone marrow and blood cell formation Muscular tissue The nervous tissue, Jay B. Angevine Blood and lymph vascular systems The immune system, Elio Raviola Thymus, Elio Raviola Lymph nodes, Elio Raviola Spleen, Elio Raviola Hypophysis The thyroid gland Parathyroid glands Adrenal glands and paraganglia Pineal gland Skin Oral cavity and associated glands The teeth The oesophagus and stomach Intestines The liver and gall-bladder Pancreas Respiratory system The urinary system Male reproductive system Female reproductive system Mammary gland The eye The ear.

2,397 citations

Journal ArticleDOI
TL;DR: The findings suggest that a substantial number of organ fibroblasts appear through a novel reversal in the direction of epithelial cell fate, which highlights the potential plasticity of differentiated cells in adult tissues under pathologic conditions.
Abstract: Interstitial fibroblasts are principal effector cells of organ fibrosis in kidneys, lungs, and liver While some view fibroblasts in adult tissues as nothing more than primitive mesenchymal cells surviving embryologic development, they differ from mesenchymal cells in their unique expression of fibroblast-specific protein-1 (FSP1) This difference raises questions about their origin Using bone marrow chimeras and transgenic reporter mice, we show here that interstitial kidney fibroblasts derive from two sources A small number of FSP1(+), CD34(-) fibroblasts migrate to normal interstitial spaces from bone marrow More surprisingly, however, FSP1(+) fibroblasts also arise in large numbers by local epithelial-mesenchymal transition (EMT) during renal fibrogenesis Both populations of fibroblasts express collagen type I and expand by cell division during tissue fibrosis Our findings suggest that a substantial number of organ fibroblasts appear through a novel reversal in the direction of epithelial cell fate As a general mechanism, this change in fate highlights the potential plasticity of differentiated cells in adult tissues under pathologic conditions

1,929 citations

Journal ArticleDOI
TL;DR: In the present work, the cellular associations were defined by the stage of development of the spermatids, which themselves were characterized by their staining reaction to the “periodic acid-Schiff” technique (hereafter referred to as PAFSA).
Abstract: Any area of any seminiferous tubule of the rat contains a few spermatogonia along the basement membrane, one or several layers of spermatocytes farther in, and groups of spermatids next to the lumen of the tubule. The present work is a systematic study of the various modes of association of these cells in what is known as the seminiferous epithelium. In the rat, development of any one generation of spermatogonia, spermatocytes, or spermatids is closely integrated with that of other generations present in the same area of the tubule. Thus, the cel!s are not arranged a t random, but are organized into well-defined cellular associations. I t was realized in the 1890’s that the various cell associations must succeed one another in time in any given area of the seminiferous tubule, and that the sequence must repeat itself indefinitely. The complete series of successive cellular associations has been named the “ spermatogenic cycle” by von Ebnerl and Regaud.? This designation is somewhat misleading and, more recently, has been used to describe the whole of spermat~genesis.~ To avoid confusion, the more exact designation “cycle of the seminiferous epithelium” or, simply, “cycle” will be used instead. The cycle of the seminiferous epithelium may be defined as that series of changes occurring in a given area of the seminiferous epithelium between two successive appearances of the same cellular association. The number of cellular associations identified by various authors within a cycle ot the seminiferous epithelium shows large (TABLE 1.) The discrepancies may be explained by the fact that many stages of development of the cells cannot be characterized with precision in preparations stained with hematoxylin. In the present work, the cellular associations were defined by the stage of development of the spermatids, which themselves were characterized by their staining reaction to the “periodic acid-Schiff”, also called “periodic acid-fuchsin sulfurous acid” technique (hereafter referred to as PAFSA). The stages through which the developing spermatids progress can be easily identified by this technique, as shown in a previous paper,l0 in which the bibliography of the subject may be found. Spermiogenesis may thus be divided into 19 stages, numbered from 1 to 19 (FIGURES 1-19). During the first 8 stages of the development of young spermatids, the seminiferous epithelium also contains a generation of older spermatids, which are released when the younger generation completes Stage 8. During the next few stages of development, the remaining spermatids are the only ones present, but when they reach Stage 15, a new generation again arises

1,625 citations

Journal ArticleDOI
TL;DR: This review summarizes and analyzes the recent data from genetic, physiological, cellular, and morphological studies that have addressed the signaling mechanisms involved in the regulation of both the paracellular and transcellular transport pathways.
Abstract: The microvascular endothelial cell monolayer localized at the critical interface between the blood and vessel wall has the vital functions of regulating tissue fluid balance and supplying the essential nutrients needed for the survival of the organism. The endothelial cell is an exquisite "sensor" that responds to diverse signals generated in the blood, subendothelium, and interacting cells. The endothelial cell is able to dynamically regulate its paracellular and transcellular pathways for transport of plasma proteins, solutes, and liquid. The semipermeable characteristic of the endothelium (which distinguishes it from the epithelium) is crucial for establishing the transendothelial protein gradient (the colloid osmotic gradient) required for tissue fluid homeostasis. Interendothelial junctions comprise a complex array of proteins in series with the extracellular matrix constituents and serve to limit the transport of albumin and other plasma proteins by the paracellular pathway. This pathway is highly regulated by the activation of specific extrinsic and intrinsic signaling pathways. Recent evidence has also highlighted the importance of the heretofore enigmatic transcellular pathway in mediating albumin transport via transcytosis. Caveolae, the vesicular carriers filled with receptor-bound and unbound free solutes, have been shown to shuttle between the vascular and extravascular spaces depositing their contents outside the cell. This review summarizes and analyzes the recent data from genetic, physiological, cellular, and morphological studies that have addressed the signaling mechanisms involved in the regulation of both the paracellular and transcellular transport pathways.

1,575 citations

Journal ArticleDOI
TL;DR: The role of Tcf-4 in colon cancer was investigated in this paper, where the authors found that Tcf7/2//- mice die shortly after birth from colon cancer.
Abstract: Mutations of the genes encoding APC or beta-catenin in colon carcinoma induce the constitutive formation of nuclear beta-catenin/Tcf-4 complexes, resulting in activated transcription of Tcf target genes. To study the physiological role of Tcf-4 (which is encoded by the Tcf7/2 gene), we disrupted Tcf7/2 by homologous recombination. Tcf7/2-/- mice die shortly after birth. A single histopathological abnormality was observed. An apparently normal transition of intestinal endoderm into epithelium occurred at approximately embryonic day (E) 14.5. However, no proliferative compartments were maintained in the prospective crypt regions between the villi. As a consequence, the neonatal epithelium was composed entirely of differentiated, non-dividing villus cells. We conclude that the genetic program controlled by Tcf-4 maintains the crypt stem cells of the small intestine. The constitutive activity of Tcf-4 in APC-deficient human epithelial cells may contribute to their malignant transformation by maintaining stem-cell characteristics.

1,570 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023487
2022700
2021217
2020203
2019183
2018197