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PubMed1977

Scanning electron microscopy of human female reproductive tract and amniotic fluid cells.

Scanning electron microscopy was used to examine surface ultrastructural characteristics of cells of the epithelium of female reproductive tract, cervical mucus, and amniotic fluid cells. The female epithelium undergoes hormone-dependent cyclical morphological alterations in cell shape, apical microvilli, ciliation, and secretory patterns. The frequency distribution of ciliated cells varies in different parts of the female reproductive tract and different segments of the same organ. In the endocervix, a few ciliated cells are randomly distributed. The density of ciliated cells is variable in several areas of the endometrium. The sparse distribution of ciliated cells in the central portion of the uterine wall may indicate a possible implantation site. According to surface ultrastructure of cells, three segments are noted in the uterotubal junction: cornual endometrium, interstitial tubal epithelium, and transitional area. The vaginal epithelium is made of flat polygonal cells with interdigitating borders and a fine interlacing network of microridges. After the menopause, the microridge pattern and distinct cell borders are lost or severely modified. Two types of fibrous structures can be found in cervical mucus: a) microfibrils that vary in diameter from 500 to 1,500 A and from bundles or networks, and b) long, thick fibers that vary in diameter from 0.5 to 5 micrometer run parallel to each other, and appear to be made up of microfibrils. Amniotic fluid cells, derived from amniotic epithelium and fetal ectoderm, consist of non-nucleated and nucleated cells with extensive microplicae.

Amniotic Fluid↗
PubMed1989

[Electron microscopic study of the iris and bulbar conjunctiva of Werner's syndrome].

We observed the iris and the upper limbal conjunctiva from the two cases of Werner's syndrome by transmission electron microscopy. Numerous microfibrils were seen between the iris pigment epithelium and the dilator muscle, and within the stroma of the conjunctiva in both patients' eyes. These similar findings in the irides of both patients suggested the relationship between the microfibrils and Werner's syndrome. Many melanosome complexes were found in iris melanocytes, and the basement membrane of the iris vessels showed marked thickening. These findings seemed to be the changes caused by aging in cases of Werner's syndrome.

Conjunctiva↗
PubMed1989

[Maturation and aging of elastic fibers].

We give a review of the maturation and aging processes of elastic fibers. Elastic fibers of adult human skin are composed of elastin (amorphous matrix) and surrounded by microfibrils (structural glycoproteins). The physiological aging of elastic fibers is a continuous process starting at the age of 40 or 50 and reaching its final state in the senium. This process is characterized by the following morphological changes: (1) decreasing number of microfibrils, (2) occurrence of osmiophilic inclusions, and (3) fragmentation and disintegration of the fibers. These alterations are due to reduced synthesis of elastin and increased deposits of lipids and calcium. As a result, the elastic fibres show increased susceptibility towards proteolytic enzymes.

Actin Cytoskeleton↗
PubMed1988

Drosophila basement membrane procollagen alpha 1(IV). II. Complete cDNA sequence, genomic structure, and general implications for supramolecular assemblies.

A Drosophila melanogaster gene for a basement membrane procollagen chain was recently identified from the sequence homology of the carboxyl (NC1) end of the polypeptide that it encodes with the corresponding domain of human and murine collagens IV (Blumberg, B., MacKrell, A. J., Olson, P. F., Kurkinen, M., Monson, J. M., Natzle, J. E., and Fessler, J. H. (1987) J. Biol. Chem. 262, 5947-5950). This gene is at chromosome location 25C. Here we report the complete 6-kilobase cDNA sequence coding for a chain of 1775 amino acids, as well as the genomic structure. The gene is composed of nine relatively large exons separated by eight relatively small introns. This organization is different from the multiple small exons separated by large introns reported for mouse and human type IV collagens (Kurkinen, M., Bernard, M. P., Barlow, D. P., and Chow, L. T. (1985) Nature 317, 177-179. Sakurai, Y., Sullivan, M., and Yamada, Y. (1986) J. Biol. Chem. 261, 6654-6657. Soininen, R., Tikka, L., Chow, L., Pihlajaniemi, T., Kurkinen, M., Prockop, D. J., Boyd, C. D., and Tryggvason, K. (1986) Proc. Natl. Acad. Sci. U.S.A. 83, 1568-1572). Drosophila and human alpha 1(IV) procollagen chains share not only polypeptide domains near their amino and carboxyl ends for making specialized, intermolecular junctional complexes, but also 11 of 21 sites of imperfections of the collagen triple helix. However, neither the number nor the nature of the amino acids in these imperfections appear to have been conserved. These imperfections of the helical sequence may be important for the supramolecular assembly of basement membrane collagen. The 9 cysteine residues of the Drosophila collagen thread domain are arranged as several variations of a motif found in vertebrate collagens IV only near their amino ends, in their "7 S" junctional domains. The relative positions of these cysteine residues provide numerous opportunities for disulfide bonding between molecules in both parallel and antiparallel arrays. There is a pseudorepeat of one-third of the thread length, and there are numerous possibilities for disulfide-linked microfibrils and networks. We propose that collagen microfibrils, stabilized by disulfide segment junctions, are a versatile ancestral form from which specialized collagen fibers and networks arose.

Amino Acid Sequence↗
PubMed1988

Spatial organization of collagen in annelid cuticle: order and defects.

The epidermis of Paralvinella grasslei (Polychaete, Annelida) is covered by an extracellular matrix, the cuticle, mainly composed as in other annelids of superimposed layers of non-striated collagen fibrils. The collagen fibrils of annelid cuticle are shown to be composed of parallel and sinuous microfibrils (thin sections and freeze-fracture replicas). The 3-dimensional organization of collagen is characterized by 2 different types of geometrical order: (a) Fibrils form a quasiorthogonal network, whose structure is comparable to that of a "plywood"; (b) Fibrils are helical, and goniometric studies show that microfibrils present a definite order within each fibril, which is termed "cylindrical twist". These 2 characteristics are those which have recently been evidenced in "blue phases", i.e., liquid crystals which are closely related to cholesteric liquid crystalline phases. Non-fluid analogues of cholesteric liquids are widespread among invertebrate cuticles and the presence of blue phase analogues suggests that a self-assembly mechanisms is involved in cuticle morpho-genesis, which is derived from that governing blue phase growth. The cuticular network presents local rearrangements of fibrils called "defects", despite the fact that they are elaborate structures which trigonal and pentagonal singularities. Branched fibrils are regularly observed. We discuss the involvement of these pattern disruptions in the cuticle growth process.

Animals↗
PubMed1985

Surface healing and histologic maturation of patent polytetrafluoroethylene grafts implanted in patients for up to 60 months.

Histologic, transmission, and scanning electron microscopic observations were made of 26 biopsy specimens from patent polytetrafluoroethylene grafts that had been implanted as arterial bypasses for up to 60 months. The results showed the rarity of host connective tissue ingrowth, the absence of neovascularization, and the limited neointimal proliferation. The defect of staining for factor VIII-related antigen by immunohistochemistry confirmed the absence of true endothelial cells at a distance from the anastomoses. Under electron microscopy the thin neointimal layer consisted mainly of fibrin, platelets, blood cells, and cellular debris. Even in prostheses implanted for the longest periods, mature collagen and elastin were not found. Tubular microfibrils (9- to 12-nm thick) could be observed. The source of such microfibrils, probably glycoproteins, remains under investigation.

Adult↗
PubMedDate not supplied

[Comparative ultrastructural study of the epithelial stromal junction in the prostatic gland].

In this paper, the authors carry out a comparative study of the structures adjacent to the alveolar periphery of the prostate-glands of men, dogs and bulls. In the three cases an E.S.J. (Epithelial-Stromal-Junction) similar to that described in the mammary gland and characterized in the first two cases by the existence of four, ultrastruct strata, consisting of the basal lamina, the somas of the adjacent fibroblasts and their cytoplasmic expansions as well as the arrangement of the intercellular, collagen microfibrils, was found to exist in this gland. In the case of the bovine prostate gland, the structural organization of the E.S.J. was basically characterized by the structural arrangement of the collagen microfibrils. The structures described constitute models on which to base future research on the hyperplastic and neoplastic processes of the prostate gland.

Age Factors↗
PubMed1975

Variability of dermal elastin visualized ultrastructurally with iron hematoxylin.

The Verhoeff iron hematoxylin-lead citrate (VIH-LC) method demonstrated vertical elastic fibers that were often composed only of microfibrillar component extending into the epidermal basement membrane in human skin. These fibers connected with a network of trabeculae composed of microfibrils and elastin fibrils in varying proportions. The large elastic fibers in the deep two thirds of the dermis consited mainly of compact bundles of small elstin fibrils in infants and of solid elastin cores with a fimbriated periphery in adults; Dermis of a 6-month-old fetus contained very few small elastic fibrils except around blood vessels. Skin of an elderly subject revealed exteme proliferation of unusual reticulated elastic fibers in various areas and disclosed abnormal nodules of elastin or collagen fibrils in finely particulate matter. Small elastin fibrils, abundant microfibrils, and intermixed individual collagen fibrils comprised an adventitial collar between sweat glands and fibroblasts. Elastin fibrils were absent from this collar in the fetus and increased with the subject's age. A permanganate-high iron diamine sequence appeared to impart density to the microfibrillar component of elastic fibers.

Adolescent↗
PubMed1979

Oxytalan fibers in the Schistosoma mansoni tegument.

In order to elucidate the nature of the fibrous network present in Schistosoma mansoni tegument, adult worms were studied by light and electron microscopy. It was suggested that this network is formed by bundles of tubular microfibrils 10--12 nm in diameter, similar to oxytalan microfibrils present in higher animals.

Animals↗
PubMed1979

[Ultrastructure of the neuroepithelial cells of the respiratory portion of the lungs in experimental inflammatory diseases of the lungs].

Neuroepithelial cells (NEC) and neuroepithelial bodies (NEB) were found in the lungs of rats among cells of the alveolar epithelium. The peculiar features of NEC structure included microvilli with microfibrils penetrating deep into the cytoplasm, and a complicated structure of the endoplasmic reticulum: reticulum membrane complex. NEC's are arrayed on the alveolar basal membrane singly, in pairs and in larger numbers forming NEB. The latter consist of cells differing in shape, size, and ultrastructure. Most of them have no microvilli with microfibrils inside. In chronic pneumonia NEC's occur more frequently, the ultrastructure of most cells being well-developed.

Animals↗
PubMed1978

Ultrastructure of fibrils in developing human and guinea-pig tympanic membrane.

The development of connective tissue of the tympanic membrane has been examined in guinea-pig embryos and fetuses from 22 days of gestation (10 mm CR length) to birth (at about 67 days, 100 mm), in neonatal animals for the first 3 weeks of life, and in human embryos and fetuses aged 6, 11, 15 and 22 weeks. In the guinea-pig up to 34 days of gestation there was little evidence of fibril formation, but from 37 days onwards fibrils were an obvious feature of the tympanic membrane area. When first observed they resembled small collagen fibrils but there was no cross-banding, and within a week to 10 days they showed the foursubunit configuration typical of adult tympanic membrane fibrils in this species. There was no increase in fibril diameter and elastic fibres were not seen. In the human fetuses small groups of collagen fibrils (already of larger diameter than guinea-pig fibrils) were apparent at 11 weeks, together with small groups of elastic microfibrils. Later specimens showed increasing numbers of cross-banded collagen fibrils and the development of the amorphous elastin component in association with the microfibrils.

Animals↗
PubMed1983

[Case of epithelioid sarcoma of the lower extremity].

A 26-year-old woman with epithelioid sarcoma is reported. An 8 X 4 cm mass was present in the pretibial region of the right leg. The operative specimen revealed a solid mass with necrosis and hemorrhage. Histologically, the tumor consisted of large round or oval cells with rich and eosinophilic cytoplasm and many vascular invasions. Electron-microscopically, the tumor was composed of light and dark cells. The dark cells showed abundant microfibrils in their cytoplasm compared to the light cells. We posit that the tumor was of synovial cell origin because of the presence of cytoplasmic microfibrils, pinocytotic vesicles and filopodias or microvilli-like structures.

Adult↗
PubMed1983

Repair in arterial tissue. An ultrastructural demonstration of proteoglycans in low temperature embedded normal and healing arterial tissue.

Low temperature embedded normal and healing arterial tissues were studied by transmission electron microscopy. The most conspicuous observation was the ultrastructurally well-preserved extracellular matrix of the arterial tissue. The proteoglycans were visible as rod-like structures (20-50 nm in width and about 200 nm in length) and radiating filaments connecting the granules to each other. The rod-like structures were removed after testicular hyaluronidase digestion. Chondroitinase ABC digestion removed most of the rod-like structures. Re-endothelialized neointima revealed a high content of rod-like structures forming a three-dimensional muralium joining together basal membrane microfibrils, collagen microfibrils and the microfibrillar component of elastin, whereas non-re-endothelialized neointima showed a reduced content of proteoglycans. The cylindrical granules may represent the proteoglycan monomer with condensed glycosaminoglycan chains.

Animals↗
PubMed1983

Elastica-positive material in the atrial endocardium. Light and electron microscopic identification.

The elastic layer of the endocardium is studied in various laboratory animals (mouse, rat, rabbit, cat, and dog) and in man. Coarse elastica-positive fibers form a tightly woven layer in the endocardium of the left atrium; the elastic layer consists of loosely arranged delicate fibers in the endocardium of the right atrium. Electron microscopy shows the elastic material to consist of homogeneous elastin (E) and of elastic fiber microfibrils (EFM). Elastic material in the endocardium of the left atrium is mainly formed of E with few EFM present. By contrast, the portion of EFM predominated that of E in elastic fibers from the right atrium, where some elastica-positive fibers even appear as pure bundles of microfibrils. This was also observed in human material obtained from aged individuals (8th decennium). It is concluded that EFM are not only progenitors of E but represent an independent fibrous component of the connective tissue.

Aged↗
PubMed1982

[Von Willebrand factor and platelet adhesion to the subendothelium of the vascular wall].

von Willebrand Factor (vWF) is a high molecular weight multimeric (1-20 X 10(6) daltons) glycoprotein which is absent or inactive in von Willebrand's disease (vWD). It is synthesized by the endothelial cell under the control of an autosome and may be released into the blood stream as well as into the subendothelium (SE). vWF is also synthesized by the megacaryocyte and localized in the alpha granules of platelets. Platelet vWF is released during aggregation. Platelets do not adhere to intact endothelial cells but interact with the SE in case of vessel wall injury. vWF plays a key role in platelet adhesion to the SE, especially at high shear rate conditions which prevail in the microcirculation. This function is confirmed by the decreased platelet adhesion observed in either vWD blood (corrected by vWF) or normal blood in the presence of polyclonal or monoclonal antibodies to vWF. The mechanism of platelet adhesion to the SE is still poorly understood. vWF only acts at high shear, ie when the flow rate is elevated and the time of interaction between platelets and the vessel wall is short. This large protein could serve as a "bridge" between the platelet membrane and the SE. It has been shown to bind first to the SE prior to platelet adhesion. Platelet and endothelial cell vWF probably also interact since they may be released in high concentration at the site of injury. The nature of the SE component to which vWF and platelets bind is unknown. Among the candidates are the basement membrane and the collagen fibers (which adsorb vWF), fibronectin, and the microfibrils (which induce vWF-mediated platelet aggregation). It is thus possible that a receptor for vWF exists on one of these components. The ristocetin-induced platelet membrane receptor for vWF seems to be glycoprotein Ib, platelet adhesion being also abnormal in Giant Platelet Syndrome. The in vivo counterpart for ristocetin is unknown, but it is possible that collagen, microfibrils, thrombin (which also induces the platelet receptor for vWF or sialidases (asialo-human vWF is able to directly bind to the platelet membrane) could replace ristocetin. Several sources of data suggest that carbohydrate is important in vWF-platelet interaction.

Animals↗
PubMed1982

Secretory features of chondrocytes related to morphogenesis of the elastic elements in the auricular cartilage.

The well-developed secreting vacuolar system is a characteristic feature of all chondrocytes (CH) during prenatal and early postnatal ontogenesis as well as of the CH near the perichondrium in the adult rat's auricular cartilage. Two kinds of secretion vacuoles exist, dense vacuole (DV) and electron lucent vacuoles (LV). The DV are heterogeneous in size, matrix appearance and origin. The factors (organ necessities and chemical maturation) responsible for the DV matrix heterogeneity are discussed. The presence of dilated rough endoplasmic cisternae with local parts of their cisternal surfaces without bound ribosomes suggest the existence of a direct secretory pathway which bypasses the Golgi complex. During prenatal ontogenesis the extracellular matrix of the auricular cartilage consists of bundles of elastic microfibrils and primary elastic fibres. The elastic microfibrils are tubular structures with a wall composed of 3-5 subunits. After birth the primary elastic fibres are joined to form intercellular septae. The presence of matrix vesicles is discussed with regard to the fine differentiation of the auricular elastic system by their lysosomal activity.

Animals↗
PubMed1981

[Visualization of oxitalan fibers in normal human skin by the alkaline tetrazolium test].

The "elastic system" of the connective tissue includes the oxytalan, the elaunin and the elastic fibers. The oxytalan fibers are formed by the microfibrillar component of the elastic fibers (elastic microfibrils). In the human skin the oxytalan fibers are found in the papillary dermis perpendicularly oriented to the dermo-epidermal junction. It was previously demonstrated by biochemical analysis that sulfur amino acids are present in the elastic microfibrils. Based on these data we could visualize the oxytalan fibers in the human dermis using the nitroblue tetrazolium (NBT) technique.

Amino Acids↗
PubMed1980

Elastogenesis in inverted vein graft. An electron microscopic study.

The process of elastogenesis was followed by electron microscopy, from 6 hours to 360 days, in autogenous inverted vein grafts of dogs. The initial processes of the new wall formation over the grafts were similar to those observed in the organization of thrombis. At 40 days, the new wall consisted of three layers comparable to the intima, media and adventitia. New elastic fibers, as demonstrated by orcein stain, were formed around fibroblasts in teh granulation tissue after 20 days and in the adventitia after 40 days. In the media, elastogenesis was associated with smooth muscle cells and began after 40 days. A basement membrane-like material accumulated around smooth muscle cells and, to a much smaller degree, fibroblasts. Elastin aggregates appeared within the basement membrane-like material. These aggregates were stainable with orcein and selectivity digestable with elastase at pH 8.8. The earliest recognizable forms of elastic fibers were the small, spherical to elongated bodies not surrounded by microfibrils. Fused and enlarging elastin aggregates were surrounded by microfibrils.

Animals↗