Desmosome-like structure between lymphocytes of developing thymus of foetal lamb

The foetal thymuses of sheep from 40 days to full term gestation were studied. The earliest thymuses that were studied were obtained from foetuses of 40 days gestation. At this stage of development the thymic tissue was formed of cords of condensed epithelial cells. Lymphopoiesis occurred in these thymuses between the thymus of 40 day old foetus and those of 42 days was striking and indicated that the onset of lymphopoiesis in the foetal sheep occurred abruptly. From 42 days onwards there was a rapid increase in the size of the thymus and in the extent of the lymphopoiesis (Fig. 1). By 45 days gestation the distribution of the lymph cells in the thymus had begun to define the cortex and medulla, and the organ was plainly lymphoid.Apart from lymphoid and epithelial cells, macrophages, erythroblasts and granulocytic myelocytes were sometimes found in the thymus (Fig. 2). Many of die lymphocytes within the cortex were closely attached to one another, the point of attachment resembling tight junctional complexes that normally found between epithelial cells (Fig. 3 and 4).

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Altered thymic epithelial cells may be decisive for Moloney virus-induced lymphoma development

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100077499 ◽

1983 ◽

Vol 41 ◽

pp. 784-785

Author(s):

U.I. Heine ◽

G.R.F. Krueger ◽

E. Munoz ◽

A. Karpinski

Keyword(s):

Epithelial Cells ◽

Leukemia Virus ◽

Light And Electron Microscopy ◽

Tumor Development ◽

Current Evidence ◽

Thymic Epithelial Cells ◽

Thymic Tissue ◽

Newborn Mice ◽

Moloney Leukemia Virus ◽

Differentiation Block

Infection of newborn mice with Moloney leukemia virus (M-MuLV) causes a T-cell differentiation block in the thymic cortex accompanied by proliferation and accumulation of prethymic lymphoblasts in the thymus and subsequent spreading of these cells to generate systemic lymphoma. Current evidence shows that thymic reticular epithelial cells (REC) provide a microenvironment necessary for the maturation of prethymic lymphoblasts to mature T-lymphocytes by secretion of various thymic factors. A change in that environment due to infection of REC by virus could be decisive for the failure of lymphoblasts to mature and thus contribute to lymphoma development.We have studied the morphology and distribution of the major thymic cell populations at different stages of tumorigenesis in Balb/c mice infected when newborn with 0.2ml M-MuLV suspension, 6.8 log FFU/ml. Thymic tissue taken at 1-2 weekly intervals up to tumor development was processed for light and electron microscopy, using glutaraldehyde-OsO4fixation and Epon-Araldite embedding.

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RB Controls Size, Cellularity, and T Cell Output of the Mouse Thymus

Blood ◽

10.1182/blood.v120.21.835.835 ◽

2012 ◽

Vol 120 (21) ◽

pp. 835-835

Author(s):

Phillip M. Garfin ◽

Patrick Viatour ◽

Dullei Min ◽

Jerrod Bryson ◽

Kenneth I. Weinberg ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Epithelial Cells ◽

Conflicts Of Interest ◽

Thymic Epithelial Cells ◽

Main Function ◽

Thymic Involution ◽

Regulatory Relationship ◽

Thymic Tissue ◽

Rb Pathway

Abstract Abstract 835 The establishment of the thymic microenvironment early in life is crucial for the production functional T cells. Conversely, thymic involution results in a decreased T cell output. Thymic involution has important health implications especially following bone marrow transplant. Our objective is to determine molecular and cellular mechanisms that will allow for regeneration of involuted thymic tissue, restore production of naïve T cells, and improve immune function while improving our understanding of immunobiology. In this pursuit, we have focused on the Retinoblastoma family of tumor suppressor proteins. The main function of the RB pathway is to restrict passage through the G1/S transition of the cell cycle. RB and its two family members, p107 and p130, mediate the action of a broad range of cellular signals to control the proliferation, survival, and differentiation status of a large number of mammalian cell types. We found that inactivation of the RB pathway in the thymus by early deletion of RB family genes prevents thymic involution, promotes expansion of functional thymic epithelial cells (TECs), and increases thymic T cell output. Moreover, we have identified a direct regulatory relationship between RB and the Foxn1 transcription factor Via E2F transcription factors, where RB/E2F complexes directly repress the Foxn1 promoter, thereby promoting involution. Thus, the RB family is a critical mediator of extra- and intra-cellular signals to regulate thymic epithelial cells and thymus function, and decreasing RB pathway function may promote regeneration of the involuted thymus and restoration of naïve T cell production in patients. Disclosures: No relevant conflicts of interest to declare.

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Intermediate filament cytoskeleton of amnion epithelium and cultured amnion epithelial cells: expression of epidermal cytokeratins in cells of a simple epithelium.

The Journal of Cell Biology ◽

10.1083/jcb.100.4.997 ◽

1985 ◽

Vol 100 (4) ◽

pp. 997-1009 ◽

Cited By ~ 74

Author(s):

S Regauer ◽

W W Franke ◽

I Virtanen

Keyword(s):

Epithelial Cell ◽

Epithelial Cells ◽

General Concept ◽

Cytoskeletal Proteins ◽

Full Term ◽

Two Dimensional Gel Electrophoresis ◽

Stratified Epithelium ◽

Epithelial Cell Lines ◽

Amnion Epithelial Cells

Using immunofluorescence microscopy and two-dimensional gel electrophoresis, we compared the cytoskeletal proteins expressed by human amnion epithelium in situ, obtained from pregnancies of from 10-wk to birth, with the corresponding proteins from cultured amnion epithelial cells and cultures of cells from the amniotic fluid of 16 week pregnancies. Epithelia of week 16 fetuses already display tissue-specific patterns of cytokeratin polypeptides which are similar, although not identical, to those of the corresponding adult tissues. In the case of the simple amnion epithelium, a complex and characteristic complement of cytokeratin polypeptides of Mr 58,000 (No. 5), 56,000 (No. 6), 54,000 (No. 7), 52,500 (No. 8), 50,000 (No. 14), 46,000 (No. 17), 45,000 (No. 18), and 40,000 (No. 19) is present by week 10 of pregnancy and is essentially maintained until birth, with the addition of cytokeratin No. 4 (Mr 59,000) and the disappearance of No. 7 (Mr 54,000) at week 16 of pregnancy. In full-term placentae, the amnion epithelium displays two morphologically distinct regions, i.e., a simple and a stratified epithelium, both of which express the typical amnion cytokeratin polypeptides. However, in addition the stratified epithelium also synthesizes large amounts of special epidermal cytokeratins such as No. 1 (Mr 68,000), 10 (Mr 56,500), and 11 (Mr 56,000). In culture amnion epithelial cells obtained from either 16-wk pregnancies or full-term placentae will continue to synthesize the amnion-typical cytokeratin pattern, except for a loss of detection of component No. 4. This pattern is considerably different from the cytokeratins synthesized by cultures of cells from amniotic fluids (cytokeratins No. 7, 8, 18, and 19, sometimes with trace amounts of No. 17) and from several so-called "amnion epithelial cell lines." In addition, amnion epithelial cells in situ as well as amnion epithelial cell cultures appear to be heterogeneous in that they possess some cells that co-express cytokeratins and vimentin. These observations lead to several important conclusions: In contrast to the general concept of recent literature, positively charged cytokeratins of the group No. 4-6 can be synthesized in a simple, i.e., one-layered epithelium. The change from simple to stratified amnion epithelium does not require a cessation of synthesis of cytokeratins of the simple epithelium type, but in this case keratins characteristic of the terminally differentiated epidermis (No. 1, 10, and 11) are also synthesized.(ABSTRACT TRUNCATED AT 400 WORDS)

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Junctional complexes of epithelial cells. Ciba Foundation Symposium 125. G. Bock and S. Clark (Eds) John Wiley and Sons Ltd.: Chichester. x + 273 pages, £27.50 (1987)

Cell Biochemistry and Function ◽

10.1002/cbf.290060325 ◽

1988 ◽

Vol 6 (3) ◽

pp. 224-224

Author(s):

J. Moss

Keyword(s):

Epithelial Cells ◽

Ciba Foundation Symposium ◽

Junctional Complexes

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A Freeze-Etching Study on Experimental Murine Mastitis

Veterinary Pathology ◽

10.1177/030098587801500507 ◽

1978 ◽

Vol 15 (5) ◽

pp. 638-648 ◽

Cited By ~ 4

Author(s):

K. Smith ◽

R. L. Chandler

Keyword(s):

Electron Microscopy ◽

Epithelial Cells ◽

Potential Barrier ◽

Mammary Glands ◽

Pathological Changes ◽

Intercellular Spaces ◽

Freeze Etching ◽

Junctional Complexes ◽

Acinar Lumen

Streptococcal mastitis was produced experimentally in mice inoculated by the intramammary route; freeze-etched preparations from the affected mammary glands were studied by electron microscopy. The inoculated cocci were seen free in the acinar lumen, within luminal phagocytes and within cells of the epithelium. No significant pathological changes were noted in the junctional complexes between secretory epithelial cells. The results were comparable to those obtained by ultrathin sectioning and indicated that, while cocci can transfer from the acinar lumen into the substance of the epithelium and towards a subepithelial location, the junctional complexes between epithelial cells present a potential barrier to movement through the intercellular spaces.

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Ultrastructure of intestinal mucosa in diarrhea-predominant irritable bowel syndrome

Physiology International ◽

10.1556/2060.106.2019.20 ◽

2019 ◽

Vol 106 (3) ◽

pp. 225-235 ◽

Cited By ~ 2

Author(s):

D-Y Zhao ◽

Q-Q Qi ◽

X Long ◽

X Li ◽

F-X Chen ◽

...

Keyword(s):

Irritable Bowel Syndrome ◽

Epithelial Cells ◽

Healthy Volunteers ◽

Confocal Laser Endomicroscopy ◽

Bowel Habit ◽

Confocal Laser ◽

Pathophysiological Mechanism ◽

Transmission Electron ◽

Junctional Complexes ◽

Irritable Bowel

Objectives Impaired intestinal barrier function has been demonstrated in the pathophysiology of diarrhea-predominant irritable bowel syndrome (IBS-D). This study aimed to describe the intestinal ultrastructural findings in the intestinal mucosal layer of IBS-D patients. Methods In total, 10 healthy controls and 10 IBS-D patients were analyzed in this study. The mucosa of each patient’s rectosigmoid colon was first assessed by confocal laser endomicroscopy (CLE); next, biopsied specimens of these sites were obtained. Intestinal tissues of IBS-D patients and healthy volunteers were examined to observe cellular changes by transmission electron microscopy (TEM). Results CLE showed no visible epithelial damage or inflammatory changes in the colonic mucosa of IBS-D compared with healthy volunteers. On transmission electron microscopic examination, patients with IBS-D displayed a larger apical intercellular distance with a higher proportion of dilated (>20 nm) intercellular junctional complexes, which was indicative of impaired mucosal integrity. In addition, microvillus exfoliation, extracellular vesicle as well as increased presence of multivesicular bodies were visible in IBS-D patients. Single epithelial cells appeared necrotic, as characterized by cytoplasmic vacuolization, cytoplasmic swelling, and presence of autolysosome. A significant association between bowel habit, frequency of abdominal pain, and enlarged intercellular distance was found. Conclusion This study showed ultrastructural alterations in the architecture of intestinal epithelial cells and intercellular junctional complexes in IBS-D patients, potentially representing a pathophysiological mechanism in IBS-D.

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Development of intercellular junctions in the pulmonary epithelium of the foetal lamb

Journal of Cell Science ◽

10.1242/jcs.32.1.307 ◽

1978 ◽

Vol 32 (1) ◽

pp. 307-324

Author(s):

E.E. Schneeberger ◽

D.V. Walters ◽

R.E. Olver

Keyword(s):

Electron Microscopy ◽

Epithelial Cells ◽

Tight Junctions ◽

Lung Development ◽

Light And Electron Microscopy ◽

Intercellular Junctions ◽

Intercellular Spaces ◽

Thin Sections ◽

Epithelial Tight Junctions ◽

Foetal Lamb

The integrity of epithelial tight junctions in foetal mammalian lungs is essential to maintain the unique ionic composition of lung liquid, and to prevent leakage of serum proteins into peripheral air spaces. In the present study the development of intercellular junctions of the lining epithelium of foetal lamb lungs during gestation was examined by light and electron microscopy. Both thin sections and freeze-fracture replicas were examined by electron microscopy. By 39 days of gestation, epithelial tight junctions consist of a minimum of 3.1 +/− 1.6 (s.D.) and a maximum of 5.8 +/− 2.0 discontinuous rows of particles and short segments of strands on P face ridges and in complementary E face grooves, while from 58 to 76 days they are composed of a network of 4.3 +/− 1.6 to 7.7 +/− 1.9 focally interrupted P face strands. Complementary replicas show that many of the discontinuities on the P face are due to separation of junctional particles on to the E face during fracturing, and not to an absence of junctional particles. From 76 days to term, epithelial tight junctions (exclusive of upper airway epithelium which was not examined) resemble those of adult lungs, and consist of a continuous network of 4.5 +/− 2.0 to 7.5 +/− 2.5 P face strands and complementary particle-free grooves. Permeability measurements, published elsewhere, indicate that the epithelium is functionally ‘tight’ from 69 days onwards. Tight junctions in peripheral air-space epithelium, therefore, are structurally continuous and functionally ‘tight’ early in foetal lung development, and form seals at one end of long, narrow intercellular spaces; these features may be important for coupled ion and water transport. When the bounding epithelial cells become flattened, these narrow intercellular spaces remain intact as a result of complex interdigitations of adjacent cell membranes. Desmosomes were present throughout gestation near the abluminal side of the tight junctions and occasionally near the base of the intercellular space. These junctions may serve to connect cells to each other at a time when tight junctions may be mechanically weak. In addition, gap junctions are associated with tight junctions from the glandular through the canalicular stages of lung development. They disappear by 120 days when the epithelial cells are differentiated.

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Feeding the Very Low-Birth-Weight Infant

Pediatrics in Review ◽

10.1542/pir.14.4.123 ◽

1993 ◽

Vol 14 (4) ◽

pp. 123-132

Author(s):

Rene Romero ◽

Ronald E. Kleinman

Keyword(s):

Birth Weight ◽

Low Birth Weight ◽

Very Low Birth Weight ◽

The United States ◽

Full Term ◽

Nutrition Support ◽

Low Birth Weight Infants ◽

Term Infants ◽

Stage Of Development ◽

Organ Systems

Unfortunately, premature birth occurs commonly in the United States. Improving the survival of very low-birth-weight (VLBW) infants depends in large part upon understanding the physiologic capabilities of their immature organ systems and providing appropriate support as they mature. Advances in the nutritional support of these infants have contributed to the better outcomes we have come to expect today, even for the smallest infants. In this review, we will discuss the limitations of gastrointestinal function and the unique nutritional requirements of very low-birth-weight infants and describe the current methods of enteral and parenteral nutrition support used to meet these requirements. Developmental Physiology By 24 to 26 weeks of gestation, the fetal gastrointestinal tract is morphologically similar to that of the full-term infant; however, functional development is far from complete. Maturation of gastrointestinal motility, digestion, and absorption continues through much of the first year of life, even in full-term infants, as a result of an interplay between the preprogrammed "biological clock" and environmental influences. The decision to feed the VLBW infant must take into account the developmental limitations as well as the potential for enhancing intestinal maturation at each stage of development (Table 1). Fetal swallowing is evident at the beginning of the second trimester.

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