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At least 1,153 records · Page 64Linked to original sources
PubMed1971

Morphogenesis of rabbit fibroma virus. Correlation with pathogenesis of the skin lesion.

Rabbit fibroma virus injected into the dermis of adult rabbit skin evokes an inflammatory, then granulomatous and finally proliferative or tumoral response. About 1 week after injection, the grossly visible nodular lesion reaches its maximum size and regresses, becoming hemorrhagic and necrotic. Unlike vacciiia, the morphogenesis of the RFV has not been validated satisfactorily. The present study shows that RFV-infected cells contain all the evolutive forms that have been identified during the course of vaccinia virus replication. In addition, long, twisting, intracytoplasmic lamellated inclusions were found in infected cells. These lamellae were composed of linear arrays of elongated, electron-dense fibers. When the inclusion was sectioned in a plane perpendicular to the fiber, the latter was found to be covered by projections approximately 160 A long, spaced at intervals of approximately 80-90 A; when sectioned tangentially, the lamellae appeared to be composed of tubules. Evidence is presented showing the similarities between the subunit of the lamellated inclusion and the virus membrane. It seems likely, therefore, that the viral membrane is covered by closely packed tubules approximately 160 A long. The lambellar inclusion is thought to represent abnormal synthesis or excessive formation of viral membranes. In addition to lamellae, which probably indicate some defect in virogenesis, some infected cells contained viral membranes partially or completely encircling the host's cell constituents, or fragments of viral membrane instead of viral matrix. Furthermore, structures resembling virus nucleoid were lying free in the viral or cytoplasmic matrix. The course of viral morphogenesis was correlated with viral multiplication and the kinetics of interferon production at the site of viral inoculation in the rabbit skin.

Animals↗
PubMed1979

Effect of oxygen concentration on morphogenesis of cranial neural folds and neural crest in cultured rat embryos.

Rat embryos, 9 1/2 days old, cultured with a 5% or 10% O2 gas phase underwent normal or near-normal cranial neurulation; however, culture at 20% or 40% O2 resulted in abnormal morphogenesis of the cranial neural folds from the 9-somite stage onwards, and the brain tube frequently failed to close. Normal morphogenesis was characterized by a narrowing V-shaped profile, development of a slightly concave neuroepithelial surface, and formation of a sharp mediad curvature of the most lateral region prior to midline apposition and fusion. These morphogenetic events were related to cellular changes within the neuroepithelium, namely cell death, onset of neural crest cell migration, and loss of apical microfilament bundles from the most lateral cells. In 20% and 40% O2-cultured embryos, failure of curvature of the neuroepithelium was associated with failure or retardation of the related cellular changes; it may therefore have been due to the maintenance of an excessive rigidity which opposed the forces involved in bringing about the final stage of brain-tube formation. Mitochondria in normal (low O2 and in vivo) embryos were of the anaerobic type, having few cristae; in high O2-cultured embryos they were of the characteristic aerobic type, indicating an adaptation to the abnormal environment.

Animals↗
PubMed1981

Investigations on the structure and morphogenesis of some arboviruses isolated in the U.S.S.R.

The morphology and some stages of morphogenesis in suckling mouse brains of hitherto serologically unclassified viruses Kaspiy (LEIV-A-63), Zavashan (LEIV-Ap-6158), Artashat (LEIV-A-2366), and Paramushir (LEIV-C-2268), isolated in the U.S.S.R., of GM-710 virus isolated in Scotland, and of Sokuluk (LEIV-K-400) virus belonging to the genus Flavivirus (family Togaviridae) were studied. Virion sizes were determined and changes in infected cells described. Based on their structure and morphogenesis, the viruses Kaspiy, Artashat, Zavashan and Paramushir were referred to the family Bunyaviridae and GM-710 virus was referred to the genus Orbivirus (family Reoviridae).

Animals↗
PubMedDate not supplied

[Morphogenesis of human rotavirus in a cell culture].

Morphogenesis of human rotavirus was studied by primary green monkey kidney cell culture by electron microscopy, at the levels of the 5th and 12th passage in the cell culture. The initial stages of rotavirus morphogenesis were shown to be associated with cytoplasmic inclusions. Nucleoid or core particles formed in the periphery of the inclusions were transported by budding to endoplasmic reticulum cavities where the final stages of virion maturation occurred. The loss of the outer membrane seems to be a component part of this process. Increasing number of virus passages in the cell culture exerted a certain effect on morphogenetic processes in the infected cells.

Animals↗
PubMed1983

The chick epiblast: a model for examining epithelial morphogenesis.

The epiblast of early chick embryos is an important model system for examining morphogenesis. Five major morphogenetic processes can be readily examined by scanning electron microscopy of the epiblast: thickening of epithelial sheets by cell elongation, folding of epithelial sheets, fusion of epithelial sheets, cavitation of epithelial cords and dispersal of cell sheets during cell migration. The purpose of this paper is to describe these morphogenetic processes, showing examples of each type. Thickening of epithelial sheets occurs by cell elongation during formation of the neural plate. Folding then ensues to form the neural groove, which is flanked laterally by the neural folds. Fusion of the neural folds closes the neural groove and separates the incipient neural tube from the overlying surface ectoderm. The caudal part of the neural tube develops much differently. Cells derived from the tail bud cluster together as an epithelial medullary cord, the peripheral cells of this cord elongate, and, simultaneously, several small cavities appear at the inner ends of the peripheral cells. All of these cavities eventually coalesce, forming a single lumen. Thus, the neural tube can be formed by markedly different morphogenetic processes depending upon its particular craniocaudal level of origin. Cell migration is exhibited by neural crest cells. In chick embryos, these cells originate from the roof of the closed neural tube. They then migrate laterad to take up residence in a variety of new locations. Scanning electron microscopy has served as an important tool, aiding us greatly in visualizing complex spatial changes that occur during the morphogenesis of epithelia.

Animals↗
PubMed1983

[Mathematical model of the morphogenesis of tumor nodules].

A mathematical model of morphogenesis of tumor nodes has been developed on the basis of the physical theory of elasticity. According to the model, one of the important morphogenetic factors of tumors consists of their internal elastic forces determining the structure of tumor nodes and intermittent phase-wise pattern of their development. The existence of a certain "critical point" in the morphogenesis of nodes (determined by the size of the tumor and its histological structure) was established the passing of which lead to a sharp decrease in the tissue pressure in node centers. The gradient of tissue pressure in tumor nodes is the leading pathogenetic factor of secondary changes and results in the appearance of a typical zonal histotopographic structure of tumors. On the basis of the rate of tumor growth alone, the model allows the intensity of their cell division to be determined and also shows the process of cell proliferation in tumor nodes to be subject to the regularities of Fibonacci number series.

Adenocarcinoma↗
PubMed1980

[Cephalic neural crests and disorders of craniofacial morphogenesis. Neurocristopathies (author's transl)].

To establish the pathogenicity, and attempt to define a classification of craniofacial malformations is a difficult task, both in animals and humans. Mention is often made of the classification developed by Paul Tessier, which according to this author "is neither based on a theory nor on an embryonic definition. It is the by-product of anatomical findings during clinical examination and operative dissections" (31). The authors propose an embryologic classification of facial malformations, based on disorders of embryonic development of cells derived from the neural crests (NC) of cephalic origin, and constituting the craniofacial ectomesenchyme. The importance of the cephalic NC derivatives in craniofacial morphogenesis is stressed, and the principal malformations of the cephalic shelf outlined, as a function of disorders occurring during the formation of the NC; migrations, proliferation, and differentiation of their derivatives. The main objective of this study was to formulate pathogenetic hypotheses, to propose a classification, and to stimulate interest in further studies in the realm of physiological and pathological craniofacial morphogenesis.

Bone Diseases, Developmental↗
PubMedDate not supplied

[Problem of sphere formation in mathematical models of morphogenesis].

The model of a process of morphogenesis is described, being a new link in the series of mathematical models of morphogenesis based on the local interactions of cells (see [6]) and the first space model of the series. A corresponding mathematical problem is formulated. The results of the proper computer calculations are published, showing that the chosen rule of motion solves the problem of sphere formation for a very large class of initial states of all investigated types of nets. The processes taking place in solving the problem of sphere formation are considered.

Computers↗
PubMed1980

[Morphogenesis of Chlamydia].

A morphological investigation was carried out on more than 12 chlamydia strains of avian and mammalian origin, multiplied in chick embryos. A number of investigations were carried out under an electronic microscope, including 674 samples of concentrated and purified chlamydia as well as yolk sacs in ultrathin sections and in negatively contrasted preparations. In the cytoplasm of the cells we proved the presence of a chlamydial matrix, an autonomous synthesis of chlamydial bodies, the morphology and polymorphism of the chlamydiae, as well as the degenerative changes in the endodermal and endothelial cells in the yolk sacs of the chick embryos. Conclusions were drawn out that in the development of chlamydia in the chick embryos no intertransformation of chlamydial bodies and no binary divisions are observed, i.e. there are no proofs of the so-called cycle of development. The development of chlamydia in chick embryos takes place in the form of specific chlamydia morphogenesis which is characterized by an autonomous synthesis and morphogenesis of chlamydia bodies on the basis of a multivacuolated matrix.

Animals↗
PubMed1981

Analysis of elongating morphogenesis of quail anterior submaxillary gland: absence of localized cell proliferation.

Quail anterior submaxillary glands elongated extensively without branching (more than sevenfold) from 8 to 10 incubation days. Investigation of mitotic activity of the rudiments in vivo showed no localized cell proliferation throughout the rudiments, and recombination experiments in vitro to examine regional differences in mitogenic activity of the surrounding mesenchyme also showed that no mesenchymal region specifically stimulates the epithelial cell proliferation. Histological observation of the rudiments showed that epithelial cells did not lengthen in a parallel direction to the long axis of the rudiment, and that mesenchymal cells encircled the epithelial cord perpendicularly to its axis. The basement membrane was obscure in the distal end of the rudiments, while it was easily detected in the other part of the rudiments. These results suggest that the elongating morphogenesis of the anterior submaxillary rudiments is not achieved by localized cell proliferation but by almost uniformly distributed cell proliferation, and mesenchymal cells surrounding the rudiment or the basement membrane may be involved in the controlling mechanisms of the elongating morphogenesis.

Animals↗
PubMed1980

Correlative light and electron microscopy of dissociated immature rat testicular cells undergoing morphogenesis in vitro.

Immature rat testicular cells undergo morphogenesis in primary culture (Davis, 1978). Depending upon the number of dissociated testicular cells added to the culture dish, spherical or tubular aggregates were formed. Spherical aggregates resulted from movement of cells into centers of aggregation and the detachment of these cells from the substratum; on the other hand, tubular aggregates resulted from detachment and retraction of the cell monolayer at certain points along its outer edge. In this investigation, the different methods of formation of aggregates by immature rat testicular cells in primary culture were examined with the scanning electron microscope (SEM). The cell types involved in such morphogenesis and their associations within completely formed structures were examined by transmission electron microscopy (TEM). In addition, the rates of formation of aggregates were established by time-lapse cinemicroscopy. During formation of spherical aggregates, the rate of recruitment of cells into centers of aggregation (0.4 +/- 0.006 micrometer/min; means +/- S.E.M., n = 78) was much slower than the rate of cell detachment during formation of tubular aggregates (11.7 +/- 1.8 micrometer/sec; means +/- S.E.M., n = 110). Although specific roles for each cell types in formation of aggregates have not been determined, the associations of cells within the two types of reformed aggregates appeared to be similar. Myofibroblast cells were located in outer cell layers and Sertoli cells were observed to underlie the layers of myofibroblasts in both types of aggregates. Germinal cells, however, were found on the outer surface of spherical aggregates, but in tubular aggregates they were located on the inner surface. Since spherical and tubular aggregates are formed by different methods, this observation suggests that rearrangement of cells, within the aggregates takes place and contributes to the internal morphology of newly formed aggregates.

Animals↗
PubMed1981

Mesenchymal control over elongating and branching morphogenesis in salivary gland development.

Recombination of the epithelium and mesenchyme between quail anterior submaxillary gland (elongating type) and quail anterior lingual or mouse submaxillary gland (branching type) was effected in vitro to clarify whether the elongating morphogenesis was directed by the epithelial or the mesenchymal component. Quail anterior submaxillary epithelium recombined with quail anterior lingual or mouse submaxillary mesenchyme came to branch. Conversely, quail anterior lingual or 12-day mouse submaxillary epithelium recombined with quail anterior submaxillary mesenchyme came to elongate, though the mesenchyme was less effective with 13-day mouse submaxillary epithelium. These results suggest that the elongating or branching morphogenesis of quail salivary glands is controlled by the mesenchyme.

Animals↗
PubMedDate not supplied

[Morphogenesis and the fine structure of Stibiobacter senarmontii].

The morphogenesis and fine structure of Stibiobacter senarmontii were studied during its cultivation in the autotrophic conditions of growth in a mineral medium as well as in a medium containing yeast extract. The morphology of the organism was shown to be variable. A young culture was represented mainly by rods with three flagella. Coccoid, club-shaped and branching forms were observed during aging of the culture. The cells multiplied by irregular division and by breaking along the partition of the parent cell. The latter process yielded cell aggregates looking like rings and hieroglyphs. Electronograms revealed a complex membrane apparatus, polyribosomes, large electron-transparent inclusions, and unknown electron-dense inclusions in the nuclear zone. The cell wall looked on cross-sections as a three-layer structure. The assignment of St. senarmontii to Gram-positive bacteria is discussed. The morphogenesis of this organism suggests that it is related to the coryneform group of bacteria.

Bacteria↗
PubMed1980

A spatial analysis of the localization of cell division and cell death in relationship with the morphogenesis of the chick optic cup.

In an attempt to analyze the possible mechanisms underlying the morphogenesis of the optic cup and the optic fissure, two features of generally accepted morphogenetic importance, mitosis and cell death, were studied in their spatial distribution in the chick. The mitotic figures and necrotic remnants visible in serial sections as stained with Feulgen/naphthol yellow-S, were marked on photomicrographs and traced on glass-plates. By piling up the plates, glass reconstructions of five successive developmental phases in the course of the third day of incubation were obtained. Mitotic figures in the walls of the optic vesicle and cup appeared to be distributed at random in all phases. Four areas of cell death, in the lateral wall of the optic vesicle, in the ventral part of the proximal optic stalk, in the uppermost part of the optic cup rim and in the outer layer of the optic cup, were found lying in a frontal plane somewhat rostral from the center of invagination. Evidence for the role of local differences in cell division and localized cell death during the morphogenesis of the optic cup, was not found. Current theories in literature and our observations were discussed. We concluded that for the present, current or conceivable theories can only be teleological explanations of circumstantial evidence. A topographical relationship between cell death and the outgrowth of the optic nerve fibers probably does exist, however. This relationship is born out by studies of congenital anomalies. Possible avenues for further investigation are suggested.

Animals↗
PubMed1978

A review of data on cell actions and cell interaction during the morphogenesis of the embryonic eye.

The early morphogenesis of the chick embryo seems to be an excellent model-system for study of morphogenetic movements, usually summarized in general terms like invagination, fusion and separation. This article reviews literature data about the early morphogenesis of the eye. The formation of lens vesicle and optic cup, during which invagination, fusion and separation are very important, were seen to represent a finely balanced interplay between cell mitosis, cell differentiation, cell death, cell transformation and cell migration. Differing observations and contradictory interpretations justify a systematic approach to to these embryological questions. We will attempt this in our next study. Apart from microscopic and submicroscopic description of closely succeeding developmental stages, three-dimensional reconstruction techniques will be indispensable to understand the spatial arrangement of the structures concerned.

Animals↗
PubMed1995

Comparison of the distinct effects of epidermal growth factor and betamethasone on the morphogenesis of the gas exchange region and differentiation of alveolar type II cells in lungs of fetal rhesus monkeys.

To compare the effects of epidermal growth factor (EGF) and betamethasone on the morphogenesis of the gas exchange region and the differentiation of the alveolar type II cell during fetal lung development, fetal rhesus monkeys (78% gestation) were treated in utero with EGF (5.33 mg/kg total dose), beta-methasone (2.6 mg/kg total dose) or the carrier, saline (control), every other day for 7 days. EGF-treated monkeys had significantly increased body and adrenal weights. Betamethasone-treated monkeys had significantly decreased body and adrenal weights. Exogenous EGF reduced cytoplasmic glycogen and increased the cytoplasmic organelle and SP-A content within alveolar type II cells. In contrast, exogenous betamethasone did not alter alveolar type II cell cytodifferentiation. Neither EGF nor betamethasone treatment significantly altered the structure of the gas exchange region as shown by a lack of change from controls in alveolar airspace size or in the fraction of the gas exchange region that was potential airspace. We conclude that at clinically relevant doses, EGF greatly accelerates the maturation of alveolar type II cells, whereas betamethasone does not. Exogenous EGF may act directly on alveolar type II cells because these cells contain EGF receptor. Neither EGF nor betamethasone had dramatic effects on the morphogenesis of the gas exchange region.

Amniotic Fluid↗
PubMedDate not supplied

[The cytostructure and morphogenesis of the rod outer segments].

This paper is a review discussing the cytomolecular structure of the rods, retinal photoreceptor cells, whose structural uniformity contributed to the progress in studies of their structure and morphogenesis in the vertebrate eye. Recent studies of protein and phospholipid metabolism in the rod inner segment have been reviewed. The structure of the outer segment connecting cilium is discussed with reference to the TEM and SEM, freeze-fracture, biochemical and immunological studies. The membranes of the rod outer segment undergo continuous renewal. The use of fine biochemical methods permitted to find differences in the structure of the plasma membrane surrounding the rod outer segment and the membrane discs, that fill this segment. Recent hypotheses dealing with morphogenesis of the rod outer segment membrane discs are also discussed. Special attention is paid to actin and myosin, as well as a small transient fraction of galactose-containing rhodopsin.

Animals↗
PubMed1994

Morphogenesis of normal human salivary gland cells in vitro.

Primary cultured human salivary gland cells were transfected with ori-defective mutant DNA of SV40. Following 2-3 weeks of transfection, slowly expanding colonies consisting of small compact cells emerged, while mock-transfected cells did not grow any more and eventually entered crisis, followed by cell death. Using limited dilution technique, we isolated 4 cell clones with distinct morphology from a single colony. Morphological observation of cells cultured on plastic dishes precisely revealed the characteristics of the constituent cells of salivary gland; i.e., three cell clones showing cuboidal- (NS-SV-DC), spindle- (NS-SV-MC), and flattened morphology (NS-SV-SC) were similar to duct-, myoepithelial-, and squamous phenotype, respectively. A remaining cell clone, polygonal in shape and with numerous secretory granules (NS-SV-AC), resembled an acinar cell. Characterization of cell clones by ultrastructural examination and search for specific antigens showed the similarity of NS-SV-DC, NS-SV-MC, NS-SV-AC, and NS-SV-SC to duct, myoepithelial, acinar, and squamous cells, respectively. Anchorage-independent growth in soft agar and tumorigenicity in nude mice were not recognized in all cell clones. These results demonstrate that establishment of cell clones with duct-, myoepithelial-, acinar-, or squamous phenotype was accomplished in the in vitro system, and that based on the evaluation of colony-forming ability in soft agar and tumorigenicity in nude mice these cell clones can be considered to be non-tumorigenic. Using the above in vitro system, we examined the effect of a reconstituted basement membrane extract, Matrigel, on the morphogenesis of cultured normal human salivary gland cells. When NS-SV-DC or NS-SV-MC were seeded on Matrigel in serum-free culture conditions, they formed round or zonal clusters on day 1; failing however, to develop into a salivary gland morphogenesis. Semithin sections of cell clones cultured on Matrigel exhibited multicellular aggregates on day 1, while on days 2 and 3 these cells lost both cell-cell and cell-Matrigel interactions and eventually entered crisis. In an attempt to understand the mechanism involved in this phenomenon, we have investigated proteolytic enzymes and their inhibitors secreted by cell clones. Although cell clones produced almost identical levels of gelatinases, they released increased amounts of plasminogen activators (PAs) as compared with a neoplastic human salivary gland cell line (HSG), which had already been demonstrated to differentiate into acinar cells when cultured on Matrigel. Obvious difference of expression level of tissue inhibitor of metalloproteinases-1 (TIMP-1) was not observed in these cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗