Seed fern (Dictyastrum chestriensis n. gen. and sp.) with a Dictyoxylon-type cortex from the Upper Mississippian of the Illinois Basin

1987 ◽  
Vol 61 (1) ◽  
pp. 184-195
Author(s):  
James R. Jennings
Keyword(s):  
Secondary Xylem ◽  
Fiber Bundles ◽  
Illinois Basin ◽  
Outer Cortex ◽  
Type Pattern ◽  
Inner Cortex

Dictyastrum chestriensis n. gen. and sp. is a seed fern that occurs in the Chester Series (Upper Mississippian) of the Illinois Basin, and is based on compressions, impressions, and pyritemarcasite petrifactions of the stem and frond. The stem has a mixed prostele with indistinct protoxylem, and the larger specimens have a thin zone of secondary xylem that contains many small rays. The inner cortex contains numerous transversely-oriented sclerotic nests, whereas the outer cortex contains prominent anastomosing fiber bundles that produce the Dictyoxylon-type pattern that is frequently observable on compressions and impressions. The petiole is massive, has an expanded base, and forks distally into unequal subdivisions. The distal frond has small pinnules with rounded lobes and corresponds to the form species Sphenopteris stricta (=S. bermudensiformis), which is used for isolated compressions and impressions. Dictyastrum chestriensis belongs to the Lyginopteridales and is intermediate morphologically between Lyginopteris and Heterangium.

Carboniferous pteridosperm studies: morphology and anatomy of Schopfiastrum decussatum

1972 ◽  
Vol 50 (12) ◽  
pp. 2649-2658 ◽  
Author(s):  
Gar W. Rothwell ◽  
Thomas N. Taylor
Keyword(s):  
Secondary Xylem ◽  
Vascular Cambium ◽  
Secondary Phloem ◽  
Outer Cortex ◽  
Southern Illinois ◽  
Leaf Arrangement ◽  
Resin Canals ◽  
Inner Cortex

The monostelic seed fern Schopfiastrum decussatum Andrews is described from a specimen collected at a Middle Pennsylvanian petrifaction locality in southern Illinois. The specimen measures 24 cm long and is about 1.1 cm in diameter. Two petioles are attached to the axis and abundant foliar material is also present. Leaf arrangement is alternate and distichous. The stem consists of an exarch protostele surrounded by a prominent zone of secondary xylem. Secondary phloem and a vascular cambium are also preserved. The cortex is characterized by an undulating outer epidermal zone consisting of alternating ridges and furrows; internally this zone is delimited by conspicuous lacunae. Sclerenchyma bands occur in the outer cortex, with prominent resin canals present in the inner cortex. The fronds are represented by dichotomizing rachides, primary pinnae, and laminar pinnules. Features of the plant are compared to those of other Carboniferous pteridosperms, and a reconstruction of Schopfiastrum is included.

Effects of angiotensin II on regional afferent and efferent arteriole dimensions and the glomerular pole

2000 ◽  
Vol 279 (2) ◽  
pp. R629-R638 ◽  
Author(s):  
Kate M. Denton ◽  
Warwick P. Anderson ◽  
Raja Sinniah
Keyword(s):  
Angiotensin Ii ◽  
Arterial Pressure ◽  
Capillary Pressure ◽  
Ang Ii ◽  
Similar Extent ◽  
Outer Cortex ◽  
Efferent Arteriole ◽  
Vascular Casting ◽  
Cortical Regions ◽  
Inner Cortex

The diversity of renal arteriole diameters in different cortical regions has important consequences for control of glomerular capillary pressure. We examined whether intrarenal angiotensin II (ANG II; 0.1, 1, or 5 ng · kg−1 · min−1) in anesthetized rabbits acts preferentially on pre- or postglomerular vessels using vascular casting. ANG II produced dose-related reductions in afferent and efferent diameters in the outer, mid, and inner cortex, without effecting arterial pressure. Afferent diameter decreased more than efferent in the outer and mid cortex ( P < 0.05) but by a similar extent in juxtamedullary nephrons ( P = 0.58). Calculated efferent resistance increased more than afferent, especially in the outer cortex (127 vs. 24 units; 5 ng · kg−1 · min−1 ANG II). ANG II produced significant dose-related increases in the distance between the arterioles at the entrance to the glomerular pole in all regions. Thus afferent diameter decreased more in response to ANG II, but efferent resistance rose more due to smaller resting luminal dimensions. The results also indicate that glomerular pole dimensions change in response to ANG II.

REACTION TISSUES IN GNETUM GNEMON A PRELIMINARY REPORT

IAWA Journal ◽  
2001 ◽  
Vol 22 (4) ◽  
pp. 401-413 ◽  
Author(s):  
P. B. Tomlinson
Keyword(s):  
Cell Walls ◽  
Tension Wood ◽  
Secondary Xylem ◽  
Secondary Phloem ◽  
Outer Cortex ◽  
Cortical Cells ◽  
Wood Fibres ◽  
Developmental Feature ◽  
Gnetum Gnemon ◽  
Clear Differentiation

Gnetum gnemon exhibits Rouxʼs model of tree architecture, with clear differentiation of orthotropic from plagiotropic axes. All axes have similar anatomy and react to displacement in the same way. Secondary xylem of displaced stems shows little eccentricity of development and no reaction anatomy. In contrast, there is considerable eccentricity in extra-xylary tissue involving both primary and secondary production of apparent tension-wood fibres (gelatinous fibres) of three main kinds. Narrow primary fibres occur concentrically in all axes in the outer cortex as a normal developmental feature. In displaced axes gelatinous fibres are developed abundantly and eccentrically on the topographically upper side, from pre-existing and previously undetermined primary cortical cells. They are wide with lamellate cell walls. In addition narrow secondary phloem fibres are also differentiated abundantly and eccentrically on the upper side of displaced axes. These gelatinous fibres are narrow and without obviously lamellate cell walls. Eccentric gelatinous fibres thus occupy a position that suggests they have the function of tension wood fibres as found in angiosperms. This may be the first report in a gymnosperm of fibres with tension capability. Gnetum gne-mon thus exhibits reaction tissues of unique types, which are neither gymnospermous nor angiospermous. Reaction tissues seem important in maintaining the distinctive architecture of the tree.

scholarly journals Quantitation of erythropoietin-producing cells in kidneys of mice by in situ hybridization: correlation with hematocrit, renal erythropoietin mRNA, and serum erythropoietin concentration

Blood ◽  
1989 ◽  
Vol 74 (2) ◽  
pp. 645-651 ◽  
Author(s):  
ST Koury ◽  
MJ Koury ◽  
MC Bondurant ◽  
J Caro ◽  
SE Graber
Keyword(s):  
In Situ Hybridization ◽  
Blood Loss ◽  
Mrna Levels ◽  
Outer Cortex ◽  
Acute Anemia ◽  
Small Clusters ◽  
Inner Cortex ◽  
Silver Grains ◽  
Serum Erythropoietin

Abstract In situ hybridization was used to quantitate the cells that produce erythropoietin (EP) in the renal cortices of mice with varying severities of acute anemia and of mice recovering from severe, acute anemia. The number of EP-producing cells in the renal cortex increased in an exponential manner as hematocrit was decreased. Individual EP- producing cells had very similar densities of silver grains in autoradiograms regardless of whether they were from normal mice or from slightly, moderately or severely anemic animals. With increasingly severe anemia, total renal EP mRNA levels and serum EP concentrations showed increases that correlated with the number of renal EP-producing cells. These results indicate that as mice become more anemic, additional cells are recruited to produce EP rather than the cells already producing EP being stimulated to increase their individual production. In mildly and moderately anemic animals, small clusters of EP-producing cells were found in the inner cortex with large areas of cortex containing no EP-producing cells. In severely anemic mice, EP- producing cells were found throughout the inner cortex with only a very few found scattered in the outer cortex and outer medulla. The data indicate that only a subset of total renal interstitial cells produce EP. During recovery from severe, acute anemia, the numbers of EP- producing cells decreased exponentially as hematocrits rose and correlated with decreases in total renal EP mRNA and serum EP concentrations. These results suggest that following an acute blood loss and during the recovery from a blood loss, the capacity to deliver oxygen, as represented by hematocrit, is the major regulator of EP production.

Renal hydrogen ion secretion after release of unilateral ureteral obstruction

1976 ◽  
Vol 231 (4) ◽  
pp. 1233-1239 ◽  
Author(s):  
K Thirakomen ◽  
N Kozlov ◽  
JA Arruda ◽  
NA Kurtzman
Keyword(s):  
Ureteral Obstruction ◽  
Renal Plasma Flow ◽  
Plasma Renin ◽  
Unilateral Ureteral Obstruction ◽  
Outer Cortex ◽  
Urinary Ph ◽  
Contralateral Kidney ◽  
Saline Loading ◽  
K Secretion ◽  
Inner Cortex

The effect of 24 h of unilateral ureteral obstruction on HCO3 reabsroption and urinary acidification was studied in dogs. The postobstructed kidney (EK) had a significantly lower glomerular filtration rate and renal plasma flow than the contralateral kidney (CK). Urinary pH prior to HCO3 loading was significantly higher in the EK as was maximal HCO3 reabsorption. Saline loading depressed HCO3 reabsorption to the same degree in both kidneys. Urinary PCO2, during HCO3 loading, and during phosphate infusion, was significantly lower in the EK than the CK. Fractional Na excretion was significantly higher in the EK than the CK after deoxycorticosterone acetate administration. Na2SO4 administration enhanced acid excretion only in the CK. K excretion was significantly lower in the EK than the CK both during HCO3 loading and Na2SO4 administration. There was redistribution of cortical blood flow from the outer cortex toward the inner cortex in the EK as compared to the CK. There was no difference in plasma renin activity from both renal veins. These data demonstrate enhanced proximal H+ secretion (which is abolished by volume expansion) and impaired distal H+ secretion by the postobstructed kidney. The distal defect is likely an effect of a generalized disorder of distal transport in that both K secretion and steroid-responsive Na reabsorption were impaired in the postobstructed kidney.

scholarly journals Quantitation of erythropoietin-producing cells in kidneys of mice by in situ hybridization: correlation with hematocrit, renal erythropoietin mRNA, and serum erythropoietin concentration

Blood ◽  
1989 ◽  
Vol 74 (2) ◽  
pp. 645-651 ◽  
Author(s):  
ST Koury ◽  
MJ Koury ◽  
MC Bondurant ◽  
J Caro ◽  
SE Graber
Keyword(s):  
In Situ Hybridization ◽  
Blood Loss ◽  
Mrna Levels ◽  
Outer Cortex ◽  
Acute Anemia ◽  
Small Clusters ◽  
Inner Cortex ◽  
Silver Grains ◽  
Serum Erythropoietin

In situ hybridization was used to quantitate the cells that produce erythropoietin (EP) in the renal cortices of mice with varying severities of acute anemia and of mice recovering from severe, acute anemia. The number of EP-producing cells in the renal cortex increased in an exponential manner as hematocrit was decreased. Individual EP- producing cells had very similar densities of silver grains in autoradiograms regardless of whether they were from normal mice or from slightly, moderately or severely anemic animals. With increasingly severe anemia, total renal EP mRNA levels and serum EP concentrations showed increases that correlated with the number of renal EP-producing cells. These results indicate that as mice become more anemic, additional cells are recruited to produce EP rather than the cells already producing EP being stimulated to increase their individual production. In mildly and moderately anemic animals, small clusters of EP-producing cells were found in the inner cortex with large areas of cortex containing no EP-producing cells. In severely anemic mice, EP- producing cells were found throughout the inner cortex with only a very few found scattered in the outer cortex and outer medulla. The data indicate that only a subset of total renal interstitial cells produce EP. During recovery from severe, acute anemia, the numbers of EP- producing cells decreased exponentially as hematocrits rose and correlated with decreases in total renal EP mRNA and serum EP concentrations. These results suggest that following an acute blood loss and during the recovery from a blood loss, the capacity to deliver oxygen, as represented by hematocrit, is the major regulator of EP production.

scholarly journals Adaptive morphoanatomy and ecophysiology of Billbergia euphemiae, a hemiepiphyte Bromeliaceae

Rodriguésia ◽  
2019 ◽  
Vol 70 ◽  
Author(s):  
Bianca Butter Zorger ◽  
Hiulana Pereira Arrivabene ◽  
Camilla Rozindo Dias Milanez
Keyword(s):  
Water Retention ◽  
Abaxial Surface ◽  
Outer Cortex ◽  
Selective Pressures ◽  
Cortex Cell ◽  
Storage Parenchyma ◽  
Cell Layers ◽  
Length Width ◽  
Lower Height ◽  
Inner Cortex

Abstract Habitats under distinct selective pressures exert adaptative pressures that can lead individuals of the same species to present different life strategies for their survival. The aim of this study was to analyse morphoanatomical and physiological traits for identification of adaptive ecological strategies related to both terrestrial and epiphytic life phases of Billbergia euphemiae. It was verified that B. euphemiae showed lower height, as well smaller length, width and foliar area in epiphytic phase than in terrestrial phase. Concerning to foliar anatomy, the thicknesses of leaf and water-storage parenchyma were higher in terrestrial phase, as densities of stomata and scales on the abaxial surface were higher in epiphytic phase. About the contents of photosynthetic pigments, only chlorophyll a/b ratio showed differences between life phases. In both habits, plants exhibited roots with absorption hair. In epiphytic phase, roots exhibited higher velamen thickness, smaller outer cortex, higher number of inner cortex cell layers and higher number of protoxylem poles. Thus, B. euphemiae individuals in epiphytic exhibited lots of traits related to water retention, once these plants are not into the ground. Besides, the plasticity observed may contribute for survival of this group in habitats submitted to modifications (e.g., climate change and other variations caused by human interference).

Anatomy of the Legume Nodule Cortex: Species Survey of Suberisation and Intercellular Glycoprotein

1996 ◽  
Vol 23 (2) ◽  
pp. 211 ◽  
Author(s):  
SM Brown ◽  
KB Walsh
Keyword(s):  
Oxygen Diffusion ◽  
Lucifer Yellow ◽  
Vascular Bundles ◽  
Outer Cortex ◽  
Lucifer Yellow Ch ◽  
Primitive Feature ◽  
Determinate Nodule ◽  
The Common ◽  
Apoplastic Barrier ◽  
Inner Cortex

Nodules of 29 species from 23 legume genera were examined for suberisation and glycoprotein deposits. Extensive suberisation of the nodule outer cortex to form a peridem was considered a primitive feature, common to non-legume and caesalpinioid nodules. The periderm was less extensive in nodules of Mimosoideae and Papilionoideae. Vascular bundles within the nodule were always surrounded by a vascular endodermis, defined by the presence of suberin on radial walls. Suberisation of the tangential walls of this endodermis was considered to be a primitive feature (present in all species examined of Caesalpinioideae and Mimosoideae, and in 10 out of 21 Papilionoideae) which may limit solute import to and export from the nodule. Glycoprotein was observed in the apoplast of the cortex in the three papilionoid species examined, but was absent in the caesalpinioid species examined. The common endodermis was recognised as an advanced feature, present only in certain species of the subfamily Papilionoideae (5 of 7, and 11 of 15 species of indeterminate and determinate nodule growth respectively). A membrane impermeant dye (lucifer yellow-CH), supplied in the rhizosphere under a mild vacuum, was observed to infiltrate through the cortex and into the infected zone in caesalpinioid nodules, and as far as the inner cortex in mimosoid and papilionoid nodules. Thus the common endodermis does not serve as an apoplastic barrier, and is unlikely to serve as a significant oxygen 'diffusion barrier'.

Vascular geometry and oxygen diffusion in the vicinity of artery-vein pairs in the kidney

2014 ◽  
Vol 307 (10) ◽  
pp. F1111-F1122 ◽  
Author(s):  
Jennifer P. Ngo ◽  
Saptarshi Kar ◽  
Michelle M. Kett ◽  
Bruce S. Gardiner ◽  
James T. Pearson ◽  
...  
Keyword(s):  
Renal Tissue ◽  
Artery Wall ◽  
Renal Veins ◽  
Arterial Diameter ◽  
Outer Cortex ◽  
Physical Relationship ◽  
Arterial Blood ◽  
Single Section ◽  
Close Relationship ◽  
Inner Cortex

Renal arterial-to-venous (AV) oxygen shunting limits oxygen delivery to renal tissue. To better understand how oxygen in arterial blood can bypass renal tissue, we quantified the radial geometry of AV pairs and how it differs according to arterial diameter and anatomic location. We then estimated diffusion of oxygen in the vicinity of arteries of typical geometry using a computational model. The kidneys of six rats were perfusion fixed, and the vasculature was filled with silicone rubber (Microfil). A single section was chosen from each kidney, and all arteries ( n = 1,628) were identified. Intrarenal arteries were largely divisible into two “types,” characterized by the presence or absence of a close physical relationship with a paired vein. Arteries with a close physical relationship with a paired vein were more likely to have a larger rather than smaller diameter, and more likely to be in the inner-cortex than the mid- or outer cortex. Computational simulations indicated that direct diffusion of oxygen from an artery to a paired vein can only occur when the two vessels have a close physical relationship. However, even in the absence of this close relationship oxygen can diffuse from an artery to periarteriolar capillaries and venules. Thus AV oxygen shunting in the proximal preglomerular circulation is dominated by direct diffusion of oxygen to a paired vein. In the distal preglomerular circulation, it may be sustained by diffusion of oxygen from arteries to capillaries and venules close to the artery wall, which is subsequently transported to renal veins by convection.

Subterranean structures and mycotrophy of the achlorophyllous Triuris hyalina (Triuridaceae)

1998 ◽  
Vol 76 (12) ◽  
pp. 2011-2019 ◽  
Author(s):  
Stephan Imhof
Keyword(s):  
Arbuscular Mycorrhiza ◽  
Adventitious Roots ◽  
Sustainable Use ◽  
Root Anatomy ◽  
Root Structure ◽  
Outer Cortex ◽  
Short Cell ◽  
External Hyphae ◽  
Xylem Elements ◽  
Inner Cortex

Triuris hyalina Miers, an unusual achlorophyllous plant, was investigated for subterranean morphology, root anatomy, and mycotrophy. Stems with scale leaves extend subterraneously to a depth of 15 cm. Pairs of adventitious roots develop at the scale leaves and clumps of apparently radiating roots, formed by accumulations of side shoot and scale leaf developments, occur. Roots consist of epidermis, short cell exodermis, three distinct layers of cortex parenchyma, endodermis, and an extremely reduced central cylinder with one or two central tracheidal xylem elements. The fungus associated with T. hyalina roots exhibits thick-walled, 6-9 µm thick, aseptate external hyphae. It penetrates the epidermis by developing appressoria and enters the cortex solely through the short cells of the exodermis. In the cortex cells, the aseptate hyphae start to coil. In the outer cortex layer, hyphae are thin, frequently branched, and most densely coiled. In the middle cortex layer they are thicker and less densely coiled, and mostly appear degenerated to clumps of amorphous fungal material. The inner cortex layer rarely becomes colonized. Vesicles occur in the outer and the middle cortex layers. This mycorrhizal pattern is interpreted as an adaption to attain a sustainable use from the endophyte. It is suggested that the mycorrhiza in Triuris hyalina be interpreted as a type of arbuscular mycorrhiza (AM). Implications for systematics and ecology are discussed.Key words: Triuris, Triuridaceae, root structure, anatomy, arbuscular mycorrhiza, myco-heterotrophy.

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