The Effect of Light and Darkness on the Fine Structure of the Retinal Clubs of Dendrocoelum Lacteum

1962 ◽  
Vol s3-103 (64) ◽  
pp. 543-548
Author(s):  
P. RÖHLICH ◽  
L. J. TÖRÖK
Keyword(s):  
Fine Structure ◽  
Structural Changes ◽  
Marginal Zone ◽  
Original Structure ◽  
Photosensitive Substance ◽  
Effect Of Light

The number and size of the vacuoles in the retinal clubs of the eye of Dendrocoelum lacteum increase considerably in animals kept in darkness. As a consequence, the volume of the whole retinal club enlarges, the microvilli forming its marginal zone becoming shorter and thicker. When exposed to light, the retinal clubs regain their original structure; the number and size of the vacuoles diminish and the zone of the microvilli widens. These structural changes are interpreted as due to a photosensitive substance which is produced in the axial cytoplasm of the club, stored in vacuoles and disintegrated by light in the zone of the microvilli.

scholarly journals Fine structure of the interdigital membranes during the morphogenesis of the digits of the webbed foot of the duck embryo

Development ◽  
1984 ◽  
Vol 79 (1) ◽  
pp. 201-210
Author(s):  
J. M. Hurle ◽  
M. A. Fernandez-Teran
Keyword(s):  
Fine Structure ◽  
Causal Relationship ◽  
Structural Study ◽  
Basal Lamina ◽  
Structural Changes ◽  
Marginal Zone ◽  
Duck Embryo ◽  
Collagenous Material

Fine structural study of interdigital membranes during formation of the digits of the duck foot reveals that the interdigital necrosis is accompanied by a high deposition of collagenous material in the epithelio—mesenchymal interface, rupture of the basal lamina and detachment of ectodermal cells into the amniotic sac. These changes are similar to those observed in the regressing interdigital membrane of the chick although their intensity and temporal extension are less pronounced in the duck. It is suggested that these changes account for the disappearance of the marginal zone of the duck interdigital membranes. The possible causal relationship between the different structural changes are discussed.

scholarly journals FINE STRUCTURAL CHANGES IN PROPLASTIDS DURING PHOTODESTRUCTION OF PIGMENTS

1964 ◽  
Vol 22 (2) ◽  
pp. 443-451 ◽  
Author(s):  
Shimon Klein ◽  
Lawrence Bogorad
Keyword(s):  
Fine Structure ◽  
Levulinic Acid ◽  
Structural Changes ◽  
Prolamellar Body ◽  
Membrane Structures ◽  
Lamellar Structures ◽  
Amino Levulinic Acid ◽  
Stroma Lamellae ◽  
Green Pigments ◽  
Bean Leaves

Etiolated bean leaves supplied δ-amino-levulinic acid in the dark synthesize large amounts of protochlorophyllide which is not converted to chlorophyllide upon illumination of the leaves. The fine structure of the proplastids is not affected by the treatment. When leaves containing "inactive" protochlorophyllide are exposed to light of 700 ft-c for 3 hours, they lose practically all their green pigments. During this period large stacks of closed membrane structures are built up in the region of the prolamellar body. These lamellar structures remain even when no or only traces of pigment are left in the leaves. In untreated control leaves the pigment content remained constant during similar illumination and the structural changes in the plastids consisted of a rearrangement of the vesicles from the prolamellar bodies into strands dispersed through the stroma; lamellae and grana formation occurred later.

scholarly journals Marginal zone B-cell lymphomas of different sites share similar cytogenetic and morphologic features [see comments]

Blood ◽  
1996 ◽  
Vol 87 (1) ◽  
pp. 299-307 ◽  
Author(s):  
J Dierlamm ◽  
S Pittaluga ◽  
I Wlodarska ◽  
M Stul ◽  
J Thomas ◽  
...  
Keyword(s):  
B Cell ◽  
Structural Changes ◽  
Marginal Zone ◽  
Chromosomal Abnormalities ◽  
Molecular Genetic ◽  
Clinical Manifestations ◽  
B Cell Lymphoma ◽  
Partial Trisomy ◽  
Chromosome 1 ◽  
Chromosomal Changes

Clinical, histologic, cytogenetic, and molecular genetic data of 31 patients with extranodal, nodal, and splenic marginal zone B-cell lymphoma (MZBCL) are presented. Despite these variable clinical manifestations, a similar spectrum of morphologic features as well as distinctive immunophenotypic findings were noted. In all cases, a monotypic B-cell proliferation consistently negative for CD5, CD10, and CD23 was found expanding the marginal zone of the B follicle with and without colonization of the follicle centers. Clonal chromosomal abnormalities were detected in 23 of the 31 patients. Recurrent aberrations included whole or partial trisomy 3 (18 cases), trisomy 18 (9 cases), and structural rearrangements of chromosome 1 with breakpoints in 1q21 (9 cases) or 1p34 (6 cases), all of which were seen in extranodal, nodal, as well as splenic MZBCL. Abnormalities of the additional chromosome 3, such as +del(3)(p13),+i(3)(q10), or structural changes involving the distal part of the long arm, were evident in 9 of the 18 cases. All recurrent abnormalities were found in MZBCL more frequently than in other histologic entities of B-cell non-Hodgkin's lymphoma (B-NHL). None of the known lymphoma-associated chromosomal changes or rearrangements of the BCL1, BCL2, BCL3, BCL6, and CMYC genes were detected. We conclude that MZBCL represent a distinct entity of B- NHL with characteristic morphologic and immunophenotypic features and particular chromosomal abnormalities, and that a close histogenetic relationship between extranodal, nodal, and splenic MZBCL is likely, although the clinical presentation may vary.

Conversaziones 1974

1975 ◽  
Vol 29 (2) ◽  
pp. 163-171
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Cell Walls ◽  
Structural Changes ◽  
Vascular Tissue ◽  
Root Systems ◽  
Plant Roots ◽  
Tracer Studies ◽  
Water Move ◽  
Intact Root

CONVERSAZIONES were held this year on 9 May and 27 June. At the first conversazione twenty-seven exhibits and two films were shown. The fine structure of plant roots in relation to transport of nutrient ions and water was demonstrated by Dr D. T. Clarkson of the A.R.C. Letcombe Laboratory, Wantage and Dr A. W. Robards of the Department of Biology, University of York. Two major pathways by which nutrients and water move radially across the cortex towards the central vascular tissue have been distinguished by the use of tracer studies of adsorption by different zones of intact root systems, microautoradiography and electron microscopy. Movement can be apoplastic through cell walls, or symplastic between cells joined by plasmodesmata. As the root ages, structural changes in the endodermis reduce movement in the former pathway but the symplast is not interrupted by the elaboration of endodermal walls because plasmodesmatal connexions remain intact. These observations help explain the contrasting extent to which different ions and water reach the shoot from young and mature parts of root systems.

Temperature Effects on Formation and Fine Structure of Brassica napus Leaf Waxes

1976 ◽  
Vol 24 (3) ◽  
pp. 309 ◽  
Author(s):  
DJ Armstrong ◽  
MI Whitecross
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Brassica Napus ◽  
Growth Temperature ◽  
Temperature Effects ◽  
Structural Changes ◽  
Leaf Waxes ◽  
Surface Waxes ◽  
Biochemical Level

Incorporation of 1-14C-palmitic acid, a precursor of leaf waxes, into leaf strips of Brassica napus was examined by thin section autoradiography and electron microscopy. Label was found to be associated with mitochrondria, Golgi vesicles and endoplasmic reticulum of epidermal cells, and also with the outer epidermal wall across which cuticular lipids are expected to migrate. Variations in growth temperatures produced structural changes in surface waxes as previously reported but no specific correlation could be found between changes in surface fine structure and variations in subcellular morphology. It is concluded that variations in wax fine structure, as influenced by growth temperature, resulted from effects at the biochemical level.

Local electronic and atomic structures of the mixed B-site ions in SrFe1−xMnxO3−δ studied with X-ray absorption spectroscopy

2021 ◽  
pp. 2140048
Author(s):  
Masatsugu Oishi ◽  
Fumito Fujishiro ◽  
Toshiaki Ina ◽  
Hirona Yamagishi ◽  
Iwao Watanabe ◽  
...  
Keyword(s):  
Fine Structure ◽  
Absorption Spectroscopy ◽  
Structural Changes ◽  
Perovskite Oxides ◽  
X Ray ◽  
Atomic Structures ◽  
Exafs Analysis ◽  
Mn Content ◽  
X Ray Absorption ◽  
Fe Ions

Local electronic and atomic structures of the B-site ions in perovskite SrFe[Formula: see text]Mn[Formula: see text]O[Formula: see text] were evaluated with X-ray absorption spectroscopy (XAS) at Mn, Fe [Formula: see text]- and [Formula: see text]-edges and O [Formula: see text]-edge. The energy of [Formula: see text]- and [Formula: see text]-edge peaks for Mn and Fe ions stayed unchanged against the change in Mn content [Formula: see text]. The analysis of Mn [Formula: see text]-edge extended X-ray absorption fine structure (EXAFS) revealed that Mn−O polyhedra was kept as an octahedron with Mn[Formula: see text] irrespective of the [Formula: see text] value, agreeing with the results of [Formula: see text]-edge spectra. The Fe [Formula: see text]-edge EXAFS analysis showed that the Fe–O distance decreased with decrease of the Mn contents, suggesting that the ratio of FeO5 polyhedra to FeO6 octahedra is increased due to smaller oxygen amount. By analyzing both the [Formula: see text]-edge and [Formula: see text]-edge spectra, we clarified the local electronic and atomic structural changes particularly occurred in the B-site mixed perovskite oxides.

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