Morphogenetic studies on excised leaves of Osmunda cinnamomea: histological studies of leaf development in sterile nutrient culture

1970 ◽  
Vol 48 (6) ◽  
pp. 1005-1016 ◽  
Author(s):  
James D. Caponetti ◽  
T. A. Steeves
Keyword(s):  
Cell Division ◽  
Cell Elongation ◽  
Leaf Development ◽  
Culture Medium ◽  
Histological Study ◽  
Cell Number ◽  
Leaf Primordia ◽  
Mature Leaves ◽  
Stage Of Development ◽  
Nutrient Culture

Leaf primordia of Osmunda cinnamomea L. explanted to a culture medium of simple composition at the end of three of their five seasons of development, complete their normal morphogenetic sequence but produce mature leaves of greatly reduced size. A histological study of the ground tissues of the rachis of cultured leaves reveals that, at least in these tissues, the size reduction results from a diminished cell number rather than from reduced cell elongation. It is apparent that, at every stage of development, cell division is greatly curtailed and that cell elongation begins precociously. Nevertheless, the pattern of development, including the distribution of mitotic activity at critical stages in the morphogenesis of the leaf, is normal. It is concluded that the effects of isolation upon leaves at this stage of development are quantitative ones upon the extent and duration of cell division and cell elongation.

Anatomy of Wild Garlic Bulbs During and Subsequent to After-Ripening

Weed Science ◽  
1972 ◽  
Vol 20 (3) ◽  
pp. 233-237 ◽  
Author(s):  
J. F. Stritzke ◽  
E. J. Peters
Keyword(s):  
Cell Division ◽  
Microscopic Examination ◽  
Cell Elongation ◽  
Leaf Primordia ◽  
Root Primordia ◽  
Ripening Period ◽  
Shoot Primordia ◽  
Division Cell ◽  
Wild Garlic

Microscopic examination of central and soft offset bulbs of wild garlic(Allium vinealeL.) at senescence of the parent plants in May and June revealed embryonic plants with numerous root primordia and four or five shoot primordia. Hardshell bulbs and aerial bulblets contained only one or two root primordia and three leaf primordia. The embryonic plants of central, soft offset, and hardshell bulbs elongated slowly during the after-ripening period. Rapid cell division, cell elongation, and initiation of new leaves took place after termination of the after-ripening period in all but the dormant hardshell bulbs. In November, new hardshell bulbs could be seen at the base of plants developed from central and soft offset bulbs.

102. THE EFFECT OF INSULIN ON EMBRYONIC STEM CELL PROGENITOR CELLS IN THE MOUSE BLASTOCYST

2009 ◽  
Vol 21 (9) ◽  
pp. 21
Author(s):  
J. M. Campbell ◽  
I. Vassiliev ◽  
M. B. Nottle ◽  
M. Lane
Keyword(s):  
Progenitor Cells ◽  
Cell Fate ◽  
Culture Medium ◽  
Inner Cell Mass ◽  
Cell Mass ◽  
Embryonic Stem ◽  
Cell Number ◽  
Human Embryos ◽  
Cell Stage ◽  
Stage Of Development

Human ESCs are produced from embryos donated at the mid-stage of pre-implantation development. This cryostorage reduced viability. However, it has been shown that this can be improved by the addition of growth factors to culture medium. The aim of the present study was to examine whether the addition of insulin to embryo culture medium from the 8-cell stage of development increases the number of ES cell progenitor cells in the epiblast in a mouse model. In vivo produced mouse zygotes (C57Bl6 strain) were cultured in G1 medium for 48h to the 8-cell stage, followed by culture in G2 supplemented with insulin (0, 0.17, 1.7 and 1700pM) for 68h, at 37 o C , in 5% O2, 6%CO2, 89% N2 . The number of cells in the inner cell mass (ICM) and epiblast was determined by immunohistochemical staining for Oct4 and Nanog. ICM cells express Oct4, epiblast cells express both Oct4 and Nanog. The addition of insulin at the concentrations examined did not increase the ICM. However, at 1.7pM insulin increased the number of epiblast cells (6.6±0.5 cells vs 4.1±0.5, P=0.001) in the ICM, which increased the proportion of the ICM that was epiblast (38.9±3.7% compared to 25.8±3.4% in the control P=0.01). This indicates that the increase in the epiblast is brought about by a shift in cell fate as opposed to an increase in cell division. The effect of insulin on the proportion of cells in the epiblast was investigated using inhibitors of phosphoinositide3-kinase (PI3K) (LY294002, 50µM); one of insulin's main second messengers, and p53 (pifithrin-α, 30µg/ml); a pro-apoptotic protein inactivated by PI3K. Inhibition of PI3K eliminated the increase caused by insulin (4.5±0.3 cells versus 2.2±0.3 cells, P<0.001), while inhibition of p53 increased the epiblast cell number compared to the control (7.1±0.8 and 4.1±0.7 respectively P=0.001). This study shows that insulin increases epiblast cell number through the activation of PI3K and the inhibition of p53, and may be a strategy for improving ESC isolation from human embryos.

CELL DIVISION AND CELL ELONGATION IN LEAF DEVELOPMENT OF XANTHIUM PENSYLVANICUM

1963 ◽  
Vol 50 (9) ◽  
pp. 891-901 ◽  
Author(s):  
Roman Maksymowych
Keyword(s):  
Cell Division ◽  
Cell Elongation ◽  
Leaf Development

Leaf morphogenesis and growth in Cyperus eragrostis (Cyperaoeae)

1996 ◽  
Vol 74 (11) ◽  
pp. 1753-1765 ◽  
Author(s):  
Connie L. Soros ◽  
Nancy G. Dengler
Keyword(s):  
Cell Division ◽  
Cell Elongation ◽  
Leaf Development ◽  
Pulse Labelling ◽  
Leaf Morphogenesis ◽  
Calcofluor White ◽  
Basal Half ◽  
Mitotic Figures ◽  
Division Cell ◽  
Leaf Extension

We identified the zones of leaf extension, cell division, cell elongation, and cell differentiation in developing leaves of a sedge species, Cyperus eragrostis Lam. (Cyperaceae). The zone of leaf extension was located by measuring the separation between pinhole markers and by observing the staining pattern of Calcofluor White after pulse-labelling growing leaves. These observations were supported by determining growth rates of control and punctured leaves and by scanning electron and light microscopy of developing leaves. The location of the zone of cell division was assessed by enumerating mitotic figures, and the zone of cell elongation was established by measuring lengths of epidermal cells in cleared leaves. These studies indicated that the zone of leaf elongation is within the basal 10–15 mm of a leaf and that cell divisions are restricted to the basal 0.2–1 mm. Radial enlargement of internal tissues begins in the basal half of the elongation zone and cells are fully differentiated within a short distance above it. Expanding leaves can be divided into three zones: zone 1, a basal meristematic zone where cell division and some cell elongation occur; zone 2, a zone above the base where cells are elongating but cell division has ceased; and zone 3, a zone where elongation is complete and cells have reached their final length. This pattern of leaf development is similar to, but more condensed than, feat found in the related monocotyledonous family, the Poaceae. Keywords: Cyperus eragrostis, leaf development, leaf extension zone, Cyperaceae, cell enlargement.

Condensed tannins in sainfoin. II. Occurrence and changes during leaf development

1995 ◽  
Vol 73 (10) ◽  
pp. 1540-1547 ◽  
Author(s):  
G. L. Lees ◽  
M. Y. Gruber ◽  
N. H. Suttill
Keyword(s):  
Electron Microscopy ◽  
Leaf Development ◽  
Condensed Tannins ◽  
Histological Study ◽  
Condensed Tannin ◽  
Light And Electron Microscopy ◽  
Leaf Primordia ◽  
Tissue Samples ◽  
Onobrychis Viciifolia ◽  
Mature Phase

A histological study examined condensed tannin (CT) formation in plant tissue samples taken from the meristematic area of very young sainfoin (Onobrychis viciifolia Scop.) seedlings and from leaflets sampled at various stages of development in mature plants growing in the greenhouse. Light and electron microscopy revealed no CT in the seedling meristem and leaf primordia, but CTs were seen very early in leaf development forming first in the vacuoles of discrete cells of the abaxial subepidermal layer when the leaflets were recognizable, but still folded. Immature leaflets collected from the growing point of a mature sainfoin plant show similar CT formation with the abaxial cell vacuoles filled with CT when the new leaves have reached the 90°-fold stage. As the leaflets unfold and mature, CTs begin to appear in the vacuoles of small, but discrete cells in the adaxial subepidermal layer while the tannin-containing cells in the abaxial subepidermal layer begin to lose CT. The CT continues to increase in the adaxial layer until typical enlarged tannin idioblasts or sacs are observed at full leaflet expansion and maturity. By this stage, the vacuoles in the abaxial layer are almost empty. In senescing leaflet samples collected from the leaf rachis attached to the last and second to last node near the base of the plant, the cells in both subepidermal layers have lost the majority of the CT that was originally formed. At senescence all tannin-containing cells appear as empty shells. We speculate that a finite amount of CT is formed in the two subepidermal layers of new leaves at different stages of early leaf development, does not increase during the mature phase, and is catabolized in older leaves and during senescence. Key words: condensed tannins, sainfoin, Onobrychis viciifolia, leaf development.

In vitro morphogenesis in Osmunda cinnamomea. The role of the shoot apex in early leaf development

1969 ◽  
Vol 47 (4) ◽  
pp. 575-580 ◽  
Author(s):  
G. S. Hicks ◽  
T. A. Steeves
Keyword(s):  
Shoot Apex ◽  
Leaf Development ◽  
Leaf Primordia ◽  
Shoot Apices ◽  
In Vitro Morphogenesis ◽  
Indeterminate Growth ◽  
Nutrient Culture ◽  
Determinate Growth

In sterile nutrient culture, shoot apices of the rhizome of Osmunda cinnamomea L., devoid of all visible foliar primordia, quickly give rise to dorsiventral leaf primordia at a presumptive leaf site (I1). It was established that these primordia were irreversibly determined as leaves. To examine the morphogenetic role of the shoot apex in governing early leaf development, this site was permanently isolated from the shoot apex by a single tangential cut. Usually, radially symmetrical shoots of indeterminate growth arose at I1 as a result of this surgery. By contrast, when organic continuity between I1 and the shoot apex was only temporarily interrupted by a cut which was subsequently allowed to heal, normally oriented dorsiventral leaf primordia formed most frequently at I1. These, too, were determined as leaves. It was concluded that the shoot apex serves as a source of determinative influences for the nascent primordium, imposing dorsiventrality and a pattern of determinate growth on the leaf site.

Cytological and Histological Study of Adult and Neonate Epidermis in Thick and Thin Skin of Various Anatomical Sites

2018 ◽  
Vol 9 (2) ◽  
Author(s):  
Hydar Muhsin Khalfa ◽  
Adnan Albideri ◽  
Haider Salih Jaffat
Keyword(s):  
Histological Study ◽  
Single Layer ◽  
Sweat Glands ◽  
Anatomical Site ◽  
Basal Cells ◽  
Histological Changes ◽  
Mature Adult ◽  
Skin Development ◽  
Stage Of Development ◽  
Thin Skin

The integumentary system covers the surface of the embryo (skin) and its specialized skin structures including hair, nails, sweat glands, mammary glands and teeth. During fetal skin development, the epidermis changes from a single layer of ectodermal cells at 7–8 days of gestation into a more apparent stratified, keratinized epithelium at 22–24 weeks. The aim of the study is to identify the histological and cytological changes that take place during neonatal and adult epidermis development. Human neonatal and adult samples were obtained from fully informed, consenting parent or releatives from Al-hilla mortary / Iraq. Neonatal samples were obtained from neonates after sudden deaths from maternity wards. Anatomical Sites included abdomen, forehead, back, shoulder and feet sole. A totoal of 15 neonates and 10 mature adults were used for this study. Fresh tissues were sectioned using a freezing cryostat. Tissues were sectioned at 5µm in -24°C and collected on microscopic slides. Slides were allowed to air dry for 30 min prior to hematoxyline and eosin staining. Tissues were also photographed using scanning electron microscopy SEM. Cytological measurements were taken using image j software and data was analysed using graph prism. Various cytological and histological changes takes place during neonatal and adult and epidermis development. Our study shows the stages of fair follicule formation as well as number of nucleated layers present at each stage of development and at different anatomical sites. Major histological changes takes places during the transition frm a neonate to a mature adult including the number of basal cells and epidermal thickness depending on the anatomical site.

scholarly journals Sound Waves Promote Arabidopsis thaliana Root Growth by Regulating Root Phytohormone Content

2021 ◽  
Vol 22 (11) ◽  
pp. 5739
Author(s):  
Joo Yeol Kim ◽  
Hyo-Jun Lee ◽  
Jin A Kim ◽  
Mi-Jeong Jeong
Keyword(s):  
Arabidopsis Thaliana ◽  
Cell Division ◽  
Root Growth ◽  
Apical Meristem ◽  
Cell Number ◽  
Root Apical Meristem ◽  
Control Group ◽  
Auxin Signaling ◽  
Ethylene Signaling ◽  
Sound Waves

Sound waves affect plants at the biochemical, physical, and genetic levels. However, the mechanisms by which plants respond to sound waves are largely unknown. Therefore, the aim of this study was to examine the effect of sound waves on Arabidopsis thaliana growth. The results of the study showed that Arabidopsis seeds exposed to sound waves (100 and 100 + 9k Hz) for 15 h per day for 3 day had significantly longer root growth than that in the control group. The root length and cell number in the root apical meristem were significantly affected by sound waves. Furthermore, genes involved in cell division were upregulated in seedlings exposed to sound waves. Root development was affected by the concentration and activity of some phytohormones, including cytokinin and auxin. Analysis of the expression levels of genes regulating cytokinin and auxin biosynthesis and signaling showed that cytokinin and ethylene signaling genes were downregulated, while auxin signaling and biosynthesis genes were upregulated in Arabidopsis exposed to sound waves. Additionally, the cytokinin and auxin concentrations of the roots of Arabidopsis plants increased and decreased, respectively, after exposure to sound waves. Our findings suggest that sound waves are potential agricultural tools for improving crop growth performance.

scholarly journals Experiments on skeletal growth and development in vitro in relation to the problem of avian phokomelia

1935 ◽  
Vol 118 (807) ◽  
pp. 133-154 ◽  
Keyword(s):  
Bone Formation ◽  
Bone Growth ◽  
Histological Study ◽  
Detailed Comparison ◽  
Specific Gene ◽  
Body Parts ◽  
Continue Development ◽  
Hatching Time ◽  
Stage Of Development

The experiments to be reported in the following pages were suggested by observations made by one of us on the so-called Creeper fowl. Creeper chickens are characterized by a disproportionate shortness of the long bones of the extremities. Histological study has shown that Creeper chickens belong in the same category as the disproportionate dwarfism of mammals known as chondrodystrophy or achondroplasia (Landauer, 1931) . The Creeper characters are inherited as a Mendelian dominant and are lethal in homozygous condition (Landauer and Dunn, 1930). Homozygous Creeper embryos generally die after about 72 hours of incubation, but in rare cases they survive beyond this stage and continue development up to nearly hatching time. These late stages of homozygous Creeper embryos exhibit striking malformations of the extremities which are known as phokomelia (Landauer, 1933). A study of the early embryonic development of homozygous Creeper embryos (Landauer, 1932) led to the conclusion that the effects of the Creeper mutation are not brought about by specific gene action on those body parts which later show deformities, but by a general retardation of body growth at a definite stage of development. This conclusion was strengthened by a detailed comparison of embryonic and post-natal bone growth in heterozygous Creeper and normal chickens (Landauer, 1934). All evidence which so far has been obtained in this work points to the conclusion that the characteristic traits of heterozygous as well as homozygous Creeper chicks are produced by an unspecific retardation of development at a time when formation of the buds of the extremities (and of the head which in homozygous embryos also shows deformities later on) are proceeding at a particularly rapid rate, thereby causing specific disturbances in the differentiation of these parts. It seemed to us that it should be possible to put these conclusions to an experimental test. The most promising way of approach appeared to be an attempt to produce in vitro the extreme abnormalities of bone formation shown by the extremities of phokomelic homozygous Creeper embryos. These abnormalities chiefly consist in (1) a general retardation of cartilage differentiation; (2) lack of bone formation; and (3) frequent partial fusion of ulna and radius on the one hand, tibia and fibula on the other, or presence of only one bone in these segments instead of two.

Expansion of pea leaves subjected to short water deficit: cell number and cell size are sensitive to stress at different periods of leaf development

1995 ◽  
Vol 46 (9) ◽  
pp. 1093-1101 ◽  
Author(s):  
Jérémie Lecoeur ◽  
Jacques Wery ◽  
Olivier Turc ◽  
François Tardieu
Keyword(s):  
Cell Size ◽  
Water Deficit ◽  
Leaf Development ◽  
Cell Number
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