Studies on the development of the air pores and air chambers of Marchanda paleacea. II. Ultrastructure of the initial aperture formation with particular reference to cortical microtubule organizing centres

1985 ◽  
Vol 63 (4) ◽  
pp. 744-756 ◽  
Author(s):  
P. Apostolakos ◽  
B. Galatis
Keyword(s):  
Endoplasmic Reticulum ◽  
Continuous Function ◽  
Cortical Microtubule ◽  
Wall Thickening ◽  
Intercellular Spaces ◽  
Morphogenetic Process ◽  
Microtubule Organizing Centres ◽  
Periclinal Walls ◽  
Thickened Wall

The initiation of the intercellular spaces (ISs) of the initial apertures (IAs) follows the formation of surface cavities (SCs). The latter represent slight deepenings in the external periclinal walls of particular superficial thallus cells at the regions where their anticlinal walls meet one another. This event keeps pace with the deposition of wall pads at the wall junctions below the SC. Afterwards, the thickened wall areas are detached and thus the IS is initiated. By an inward development the IS reaches the subprotodermal layer. This is carried out by the coordination of three gradual processes: the inward spreading of the local wall thickening and the following detachment and expansion of the thickened regions. The findings favour the conclusion that the opening of the IS is the outcome of a highly controlled morphogenetic process. The interphase IA cells possess a well-organized cortical microtubule (MT) cytoskeleton, particularly at the area where the IS opens. In these regions, sets of anticlinal and periclinal MTs appear. During the SC stage the anticlinal MTs dominate, while during IS formation, the periclinal ones are most abundant. The above MTs, as well as other ones entering deeper in the cytoplasm, initially converge on the cortical cytoplasm adjacent to the SC and later on the region surrounding the lower part of the growing IS, where vesicles and endoplasmic reticulum are gathered. The observations suggest the continuous function of cortical MT organizing centres in the cytoplasm and (or) the adjoining plasmalemma, initially underneath the SC and later below the lower part of the growing IS, where local wall thickenings are deposited.

Morphological peculiarities of seeds of some species of the genus Epipactis Zinn. (Orchidaceae Juss.) of Ukrainian flora

2019 ◽  
Vol 11 (1) ◽  
pp. 93-100
Author(s):  
T Ljubka ◽  
O Tsarenko ◽  
I Tymchenko
Keyword(s):  
Seed Coat ◽  
Cell Walls ◽  
Morphological Study ◽  
Population Level ◽  
Intercellular Spaces ◽  
Different Populations ◽  
Periclinal Walls ◽  
High Degree ◽  
Shape And Size ◽  
Generative Organs

The investigation of macro- and micromorphological peculiarities of seeds of four species of genus Epipactis (Orchidaceae) of Ukrainian flora were carried out. The genus Epipactis is difficult in the in in taxonomic terms and for its representatives are characterized by polymorphism of morphological features of vegetative and generative organs of plants and ability of species to hybridize. The aim of the research was to perform a comparative morphological study of seeds of E. helleborine, E. albensis, E. palustris, E. purpurata and to determine carpological features that could more accurately identify species at the stage of fruiting. A high degree of variation in the shape of the seeds in different populations within the species and overlap of most quantitative carpological characteristics of studied species are noted. There were no significant differences in micromorphological features of the structure of the testa at species or population level. The reticulate surface of the testa is characteristic of all species, the cells of testa are mostly elongated, penta-hexagonal, individual cells almost isodiametric-pentagonal. From the micropillary to the chalasal end, a noticeable change in the shape and size of the seed coat cells is not observed. There are no intercellular spaces, the anticlinal walls of adjacent cells are intergrown and the boundaries between them become invisible. The outer periclinal walls have a single, mainly longitudinal thin ribbed thickenings. Anticlinal cell walls are thick, dense, smooth. The longitudinal Anticlinal walls are almost straight, transverse - straight or sometimes curved in some cells. Epicuticular deposits on the periclinal walls are absent. It is concluded that the use of macro and micromorphological characteristics of seeds of these species for clearer diagnosis at the stage of fruiting is low informative.

THE ORGANIZATION OF CYTOPLASMIC COMPONENTS DURING THE PHASE OF CELL WALL THICKENING IN DIFFERENTIATING CAMBIAL DERIVATIVES OF ACER RUBRUM

1965 ◽  
Vol 43 (11) ◽  
pp. 1401-1407 ◽  
Author(s):  
James Cronshaw
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Plasma Membrane ◽  
Osmium Tetroxide ◽  
Acer Rubrum ◽  
Middle Layer ◽  
Wall Thickening ◽  
Cytoplasmic Microtubules ◽  
Derivatives Of ◽  
Peripheral Cytoplasm

Cambial derivatives of Acer rubrum have been examined at stages of their differentiation following fixation in 3% or 6% glutaraldehyde with a post fixation in osmium tetroxide. At early stages of development numerous free ribosomes are present in the cytoplasm, and elements of the endoplasmic reticulum tend to align themselves parallel to the cell surfaces. The plasma membrane is closely applied to the cell walls. During differentiation a complex system of cytoplasmic microtubules develops in the peripheral cytoplasm. These microtubules are oriented, mirroring the orientation of the most recently deposited microfibrils of the cell wall. The microtubules form a steep helix in the peripheral cytoplasm at the time of deposition of the middle layer of the secondary wall. During differentiation the free ribosomes disappear from the cytoplasm and numerous elements of rough endoplasmic reticulum with associated polyribosomes become more evident. In many cases the endoplasmic reticulum is associated with the cell surface. During the later stages of differentiation there are numerous inclusions between the cell wall and the plasma membrane.

STRUCTURAL CHANGES IN PRIMARY LENTICELS OF NORWAY SPRUCE OVER THE SEASONS

IAWA Journal ◽  
2003 ◽  
Vol 24 (2) ◽  
pp. 105-116 ◽  
Author(s):  
Sabine Rosner ◽  
Birgit Kartusch
Keyword(s):  
Norway Spruce ◽  
Structural Changes ◽  
Phase 1 ◽  
Late Summer ◽  
Early Summer ◽  
Climatic Conditions ◽  
Wall Thickening ◽  
Intercellular Spaces ◽  
Phase 3

Seasonal production of lenticel tissues was compared between Norway spruce trees (Picea abies (L.) Karst.) from a mountain site (1200 m), where they are autochthonous, and seven allochthonous lowland sites (250–600 m).The periodic changes of lenticel structure were grouped into four stages, based on the degree of their opening: phase 1 - winter dormancy; phase 2 - beginning of meristem activity in spring; phase 3 - production of non-suberised filling tissue in early summer, which causes the disruption of the closing layer formed in the previous growing season; and phase 4 - differentiation of a new closing layer in late summer. Structural changes in lenticels of P. abies may be interpreted as a long-term reaction to climatic conditions, balancing transpiration and respiration. During the most active period of wood production, lenticels were found in their most permeable phase, phase 3. The production of a new closing layer takes place when summer temperatures reach maximum values, and when demand for effective regulation of transpiration is high. During phase 4 transpiration is successfully controlled because differentiating cells of the new closing layer are already suberised, although not in their final rounded shape, and therefore have small intercellular spaces. High annual variability in stratification of lenticel tissues, such as the proportion between closing layer and filling tissue, wall thickening and size of intercellular spaces, also indicates possible long-term regulation mechanisms for transpiration.

The organization of microtubules in guard cell mother cells of Zea mays

1982 ◽  
Vol 60 (7) ◽  
pp. 1148-1166 ◽  
Author(s):  
B. Galatis
Keyword(s):  
Zea Mays ◽  
Nuclear Envelope ◽  
Guard Cell ◽  
Cortical Microtubule ◽  
Colchicine Treatment ◽  
Early Prophase ◽  
Cortical Regions ◽  
Periclinal Walls ◽  
Mother Cells ◽  
Dictyosome Vesicles

The cortical interphase microtubules of the guard cell mother cells (GMCs) of Zea mays form a well-grouped band (interphase microtubule band, IMB) lining the midregion of the lateral and periclinal walls, which are the only expanding walls during interphase. In advanced interphase GMCs, another population of microtubules emerge from the cortical cytoplasm of the midregion of the periclinal walls, entering deep into the cytoplasm. Elongated proplastids converge on the above cortical regions, possibly aligned by the microtubules with which they are associated.The IMB depolymerizes prior to mitosis and a preprophase microtubule band (PMB) is organized adjacent to the proximal, distal, and periclinal walls. In transverse sections the preprophase – early prophase nucleus appears slightly elliptical or spindle-shaped, sometimes exhibiting acute angular profiles at its poles. Extranuclear microtubules closely juxtaposed with the nuclear envelope converge on the "poles" of the nucleus, close to the regions of the PMB adjacent to the periclinal walls. The observations suggest a local interplay between the PMB and (or) the PMB cytoplasmic site on the one hand and the nuclear envelope and (or) the extranuclear microtubules on the other.The microtubules of both bands lining the periclinal walls and the sites of their junctions with the anticlinal ones are more closely grouped than those running along the anticlinal walls, and they exhibit intimate associations with numerous dictyosome vesicles. This preferential gathering of dictyosome vesicles, among others, possibly manifests a mechanism promoting the thickening of the expanding regions of the above walls.The inhibition of the symmetrical divisions of the GMCs by a continuous colchicine treatment leads to the formation of epidermal idioblasts possessing some of the characteristidcs of the guard cells. Furthermore, in the absence of microtubules, local wall thickenings are deposited in the middle of the periclinal walls and at their junctions with the anticlinal ones.From the observations it seems likely that guard cell differentiation commences in GMC, and that the cortical cytoplasm and (or) the plasmalemma of the midregion and the edges of the periclinal walls of the GMC possess some factor(s) favouring their preferential thickening. Cortical microtubule organizing centres (MTOCs) appear to be localized in these regions and activated in a programmed fashion.

Certain aspects of xylem differentiation in corn

1972 ◽  
Vol 50 (9) ◽  
pp. 1795-1804 ◽  
Author(s):  
L. M. Srivastava ◽  
A. P. Singh
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Wall Thickening ◽  
Xylem Differentiation ◽  
Cytoplasmic Protein ◽  
Wall Deposition ◽  
Vessel Elements ◽  
Parenchyma Cells ◽  
Vacuolar Membranes

Differentiation of vessel elements in corn is accompanied by marked changes in nearly all organelles except plastids. The young cells increase in volume and apparently synthesize new cytoplasmic protein. The initiation of wall thickening is accompanied by an aggregation of microtubules in specific locations and an increase in the number of mitochondria and dictyosomes. During the period of active wall deposition, the endoplasmic reticulum (ER) shows a highly elaborate form, harbors intralamellar tubules, and nearly blankets those parts of the wall which remain unthickened. Dictyosomes seem to produce at least two types of vesicles, one of which may serve as a carrier of lignin precursors. The final autolysis involves a progressive removal of vacuolar membranes, plastids, dictyosomes, vesicles associated with secretion of noncellulosic polysaccharides, microtubules, and finally plasmalemma, parts of cell wall, and cytoplasm. Mitochondria and ribosomes are degenerated. The ER probably plays an important role in this autolysis. The parenchyma cells associated with vessel elements are rich in mitochondria.

Identification of a spindle-associated protein in ciliate micronuclei

1989 ◽  
Vol 93 (2) ◽  
pp. 287-298
Author(s):  
GUY KERYER ◽  
NICOLE GARREAU DE LOUBRESSE ◽  
NICOLE BORDES ◽  
MICHEL BORNENS
Keyword(s):  
Cell Cycle ◽  
Monoclonal Antibody ◽  
Nuclear Envelope ◽  
Mammalian Cells ◽  
Fibrous Material ◽  
Cortical Microtubule ◽  
Ciliated Protozoa ◽  
Paramecium Tetraurelia ◽  
Electron Microscope Level ◽  
Microtubule Organizing Centres

Ciliated protozoa display a nuclear dualism, with germinal micronuciei and a somatic macronucleus. During mitosis, which proceeds without disruption of the nuclear envelope, a spindle is organized within the micronucleus from, presumably, intranuclear microtubule-organizing centres (MTOCs). In order to characterize these MTOCs, monoclonal antibodies generated against human centrosomes were screened on several ciliates and particularly on Paramecium tetraurelia. In this ciliate, the monoclonal antibody CTR 532, which decorates centrosomal and spindle-associated components in mammalian cells, specifically labelled the micronuclei during interphase. At the electron-microscope level, it stained a fibrous material surrounding microtubules localized on the inner face of the nuclear envelope. During mitosis this decoration extended all over the metaphase spindle. At all stages of the cell cycle, the decoration remained specific to the micronucleus and was absent not only from all of the various cytoplasmic and cortical microtubule arrays but also from the macronuclei, even at early stages of their development from the zygotic nucleus. CTR 532 recognizes a single 170x103 Mr polypeptide in the cytoskeletal fraction that contains micronuclei and this polypeptide is absent in the cytoskeletal fraction of amicronucleate cells.

scholarly journals THE FINE STRUCTURE OF DIFFERENTIATING XYLEM ELEMENTS

1965 ◽  
Vol 24 (3) ◽  
pp. 415-431 ◽  
Author(s):  
James Cronshaw ◽  
G. Benjamin Bouck
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Fine Structure ◽  
Secondary Wall ◽  
Osmium Tetroxide ◽  
Light And Electron Microscopy ◽  
Wall Thickening ◽  
Direction Parallel ◽  
Secondary Wall Thickening ◽  
Xylem Elements

Differentiating xylem elements of Avena coleoptiles have been examined by light and electron microscopy. Fixation in 2 per cent phosphate-buffered osmium tetroxide and in 6 per cent glutaraldehyde, followed by 2 per cent osmium tetroxide, revealed details of the cell wall and cytoplasmic fine structure. The localized secondary wall thickening identified the xylem elements and indicated their state of differentiation. These differentiating xylem elements have dense cytoplasmic contents in which the dictyosomes and elements of rough endoplasmic reticulum are especially numerous. Vesicles are associated with the dictyosomes and are found throughout the cytoplasm. In many cases, these vesicles have electron-opaque contents. "Microtubules" are abundant in the peripheral cytoplasm and are always associated with the secondary wall thickenings. These microtubules are oriented in a direction parallel to the microfibrillar direction of the thickenings. Other tubules are frequently found between the cell wall and the plasma membrane. Our results support the view that the morphological association of the "microtubules" with developing cell wall thickenings may have a functional significance, especially with respect to the orientation of the microfibrils. Dictyosomes and endoplasmic reticulum may have a function in some way connected with the synthetic mechanism of cell wall deposition.

scholarly journals Duodenal Stenosis Due to Carcinoma of the Lower Bile Duct: A Case Report

2020 ◽  
Vol 13 ◽  
pp. 117954762091945
Author(s):  
Takumi Maki ◽  
Atsushi Irisawa ◽  
Kenji Notohara ◽  
Goro Shibukawa ◽  
Ai Sato ◽  
...  
Keyword(s):  
Bile Duct ◽  
Clinical Course ◽  
Needle Aspiration ◽  
Papillary Adenocarcinoma ◽  
Duodenal Wall ◽  
Wall Thickening ◽  
Duodenal Stenosis ◽  
Endoscopic Retrograde ◽  
Detailed Evaluation ◽  
Thickened Wall

An 83-year-old man was referred to our hospital for a detailed evaluation for vomiting. Esophagogastroduodenoscopy and abdominal computed tomography showed duodenal stenosis with wall thickness. Biopsy including endoscopic ultrasound-guided fine-needle aspiration of the thickened wall showed inflammation without malignancy. During the clinical course, wall thickening of the distal bile duct appeared. Biopsy under endoscopic retrograde cholangiography showed papillary adenocarcinoma. Surgery revealed that the tumor had widely invaded the duodenal wall from the outside; therefore, only gastrojejunostomy was performed. It was hypothesized that the cholangiocarcinoma had progressed to the serosal side, disseminated in the peritoneum, infiltrated the duodenal serosa, and caused duodenal stenosis.

Intestinal pathology associated with Trichostrongylus colubriformis infection in sheep: vascular permeability and ultrastructure of the mucosa

Parasitology ◽  
1975 ◽  
Vol 70 (2) ◽  
pp. 173-180 ◽  
Author(s):  
I. K. Barker
Keyword(s):  
Endothelial Cells ◽  
Endoplasmic Reticulum ◽  
Small Intestine ◽  
Vascular Permeability ◽  
Intestinal Function ◽  
Intercellular Spaces ◽  
Protein Loss ◽  
Trichostrongylus Colubriformis ◽  
Intestinal Pathology ◽  
Epithelial Sheet

Increased permeability of capillaries and venules, labelled with colloidal carbon, was observed in the superficial mucosa of the small intestine of sheep infected with Trichostrongylus colubriformis. The labelled vessels were restricted to infected portions of the gut, and the intensity of labelling appeared to be related to density of the worm population. Open junctions were seen between endothelial cells in permeable vessels. In moderately atrophic infected intestine, enterocytes were domed, had sparse, short, distorted microvilli and many polyribosomes. Tight junctions between enterocytes seemed to be intact and distended intercellular spaces were seen. In more severely atrophic mucosa, enterocytes had distended mitochondria and endoplasmic reticulum, bizarre shapes, and the continuity of the epithelial sheet was occasionally disrupted. There was oedema in the lamina propria and neutrophils were seen in migration to the lumen of the gut. The possible mechanisms inducing these changes and their significance in terms of plasma protein loss and intestinal function are discussed.

Aerial root cap structure of an orchid, Epidendrum

1981 ◽  
Vol 59 (9) ◽  
pp. 1702-1708 ◽  
Author(s):  
Susan J. Blackman ◽  
Edward C. Yeung
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Cell Walls ◽  
Root Cap ◽  
Wall Material ◽  
Wall Thickening ◽  
Cell Wall Material ◽  
Random Orientation ◽  
Mitotic Figures ◽  
Distal Cell

The root cap of Epidendrum ibaguense has a rounded profile with a root cap junction present between the cap and meristem. A distinct columella region is lacking. Mitotic figures are infrequent in the root cap initial cells. The root cap initials and their immediate derivatives show few dictyosomes, little endoplasmic reticulum, plastids lacking starch, and few vacuoles. As the cells age they increase in size and show increasing vacuolation. Plastids increase by division and accumulate large starch grains. Throughout the root cap, amyloplasts maintain a random orientation in the cell. Endoplasmic reticulum also becomes more abundant as the cells age. In older cells, hypertrophied dictyosomes are evident and cell wall material begins accumulating between the distal cell wall and the plasmalemma. Wall thickening progresses with age though radial walls remain largely unthickened. Vacuolation progresses and is followed by complete senescence leaving only the cell walls.

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