The relation of the two blastomeres to the polar lobe in Dentalium

Development ◽  
1968 ◽  
Vol 20 (1) ◽  
pp. 101-105
Author(s):  
N. H. Verdonk
Keyword(s):  
Normal Development ◽  
Bilateral Symmetry ◽  
Polar Lobe ◽  
Posterior Side ◽  
First Case

Experiments on the influence of the polar lobe on the development of molluscs have shown that after removal of the polar lobe cleavage is radially symmetrical and indications of bilateral symmetry do not appear (Wilson, 1904: Dentalium; Clement, 1952: Ilyanassa). In normal development the polar lobe fuses with one of the two cells of the trefoil stage, and this cell becomes the posterior side of the embryo. The question now arises whether the polar lobe fuses in an arbitrary way with one of the blastomeres at first cleavage, which then becomes the CD cell. Another possibility is that one of the two blastomeres at the trefoil stage is already predetermined to become the CD cell, with which the polar lobe always fuses. In the first case dorsoventrality is determined epigenetically; in the second case it is preformed. Morgan (1936) tried to solve this question by removing one of the blastomeres at the trefoil stage in Ilyanassa.

Protein synthesis during Ilyanassa development: effect of the polar lobe

Development ◽  
1973 ◽  
Vol 29 (2) ◽  
pp. 267-281
Author(s):  
G. Teitelman
Keyword(s):  
Protein Synthesis ◽  
Normal Development ◽  
Disc Electrophoresis ◽  
Developmental Differences ◽  
Protein Solutions ◽  
Polar Lobe ◽  
Stages Of Development ◽  
Morphogenetic Factors ◽  
Slow Moving ◽  
The One

Removal of the polar lobe at the trefoil stage of the first cleavage division of Ilyanassa embryos causes abnormalities much later in development. To determine if the developmental differences between normal and delobed embryos were reflected in alterations in protein synthesis and at what stages of development these become evident, protein solutions were separated by disc electrophoresis on basic acrylamide gels. For the analysis of the newly synthesized proteins, two protein samples, one labelled with 14C and the other with 3H, were combined in the same electrophoretic column. Each was prepared from normal embryos or lobeless embryos at different stages of development. The distribution of the two groups of differentially labelled proteins was compared by a determination, for each fraction, of the ratio of the normalized 3H/14C counts for that particular fraction (R = 3H/14C). The plot of R versus fraction number was studied for various combinations of samples. During normal development the profile of labelled proteins remains unchanged until the onset of visible differentiation. At this stage, around day 4 of development, there are changes in biosynthesis revealed by a greater emphasis on the synthesis of slow moving proteins. The profile of labelled proteins of lobeless embryos remains unchanged up to the 5th day of development. This result is correlated with the absence, in the lobeless embryos, of many of the visible differentiations. Preliminary studies revealed that the spectrum of labelled proteins of the polar lobe is identical to the one present in lobeless embryos and in normal embryos in early stages of development. This suggests the possibility that the morphogenetic factors associated with the polar lobe are not among the newly synthesized proteins. A hypothesis is presented to account for the effects on morphogenesis and protein synthesis which are produced by removal of the polar lobe.

The development of Bithynia tentaculata (Prosobranchia, Gastropoda) after removal of the polar lobe

Development ◽  
1974 ◽  
Vol 31 (2) ◽  
pp. 415-422
Author(s):  
James N. Cather ◽  
Nico H. Verdonk
Keyword(s):  
Bilateral Symmetry ◽  
Columnar Epithelium ◽  
Polar Lobe ◽  
Bithynia Tentaculata

The polar lobe of the egg of Bithynia, with a volume of less than 1% of that of the egg, was surgically removed. Lobeless embryos form no mesentoblast cell nor mesoderm bands. They fail to establish bilateral symmetry and to form eyes, foot, operculum, shell, etc. They always differentiate larval head cells, ganglia, larval liver and mesenchyme and sometimes columnar epithelium, stomodeal entrance cells, endodermal tubes and muscles. These results are discussed in relation to the structure of the lobe, the analysis of development of Bithynia and to similar experiments in other species.

Specification of first quartet micromeres in Ilyanassa involves inherited factors and position with respect to the inducing D macromere

Development ◽  
1998 ◽  
Vol 125 (20) ◽  
pp. 4033-4044 ◽  
Author(s):  
H.C. Sweet
Keyword(s):  
Normal Development ◽  
Eye Development ◽  
Ilyanassa Obsoleta ◽  
Cleavage Stage ◽  
Polar Lobe ◽  
Cell Stage ◽  
Cleavage Stage Embryo ◽  
Inductive Interaction ◽  
Stage Embryo ◽  
Transplantation Experiments

In the embryos of the gastropod Ilyanassa obsoleta, the development of several ectodermal structures requires an inductive interaction between the micromeres and the D macromere. The first quartet micromeres (1a, 1b, 1c and 1d) contribute to the head of the larva and descendants of 1a and 1c normally develop the eyes. The eyes do not develop if 1a and 1c are removed at the eight-cell stage. However, regulative eye development may occur if the precursors of 1a and 1c are removed at the two- or four-cell stage. One purpose of this study was to demonstrate which cells of the cleavage-stage embryo have the potential to develop an eye. The results of blastomere deletion experiments suggest that only the first quartet micromeres have this ability. In addition, the 1b micromere was found to be equivalent to 1a and 1c, but 1d was found to have a poorer eye-forming ability. A second purpose of this study was to examine how eye development is normally restricted to the 1a and 1c micromeres. Cell transplantation experiments demonstrate that the proximity of a first quartet micromere relative to the inducing D macromere is important for determining whether or not it will go on to develop an eye. The 1b micromere may not develop an eye during normal development because it is too far from the D macromere. However, the eye-forming ability of the 1d micromere is not influenced by its close position to the D macromere, but is restricted by its polar lobe lineage.

scholarly journals Morphogenesis in Micrasterias

Development ◽  
1975 ◽  
Vol 33 (1) ◽  
pp. 117-126
Author(s):  
T. C. Lacalli
Keyword(s):  
Cell Wall ◽  
Laser Irradiation ◽  
Tip Growth ◽  
Normal Development ◽  
Polar Lobe ◽  
Growth Processes ◽  
Combined Action

The final form of the polar lobe and lateral wings of developing semicells of M. rotata results from combined action of three growth processes: tip growth, branching and lobe broadening. Tip giowth unaccompanied by branching or broadening occurs during normal development in M. radiata, but is observed only under abnormal conditions (e.g. raised temperature) in M. rotata. When branching and broadening do occur, they occur together and for this reason may be causally related. Autoradiograms demonstrate that specific patterns of cell wall incorporation can be associated with each of the three processes in M. rotata. Autoradiographic patterns found in the polar lobe differ from those found in wings. The growing polar lobe also responds to laser irradiation differently from the wings; lasings occasionally cause duplication of the polar lobe.

Hemophilia B in A Girl with Deletion of a Short Arm of One X-Chromosome

1975 ◽  
Author(s):  
A. Spinelli ◽  
W. Sohmid ◽  
P. W. Straub
Keyword(s):  
Turner Syndrome ◽  
X Chromosome ◽  
Normal Development ◽  
Clinical Findings ◽  
Factor Ix ◽  
Hemophilia B ◽  
New Mutation ◽  
First Case ◽  
Age Factor ◽  
Recalcification Time

12 females with hemophilia B have been reported. One had a 45 XO-Turner syndrome, one an XX-XO mosaicism. We report the first case with deletion of a short arm of one X-chromosome.The 1-yr. girl was referred because of spontaneous hematomas and bruising. Durning observation a lingual hemorrhage could be stopped only with factor IX, Clinical findings were normal, development corresponding to the age. Factor IX repeatedly was < 1%, PTT 81 sec (n. 40–55), the recalcification time 375 sec (n. 80–120). Other findings were normal, including factors VIII, XI, XII. Parents, 2 siblings and 8 family members of the mother were also normal.Chromosomal analysis: deletion of one short arm of one X-chromosome. Deletion being known to suppress the activity of the entire affected chromosome, the functional result is that of the XO-Turner syndrome. The morphologically normal X-chromosome must have the hemophilia abnormality. The possibilities that the mother is a carrier or that a new mutation occurred, could not be excluded. The possibility that the father is hemophilic, would imply that the examined father is not the child’s father and has yet to be explored.

Memoirs: The Early Development of Astropecten Irregularis, with Remarks on Duplicity in Echinoderm Larvae

1925 ◽  
Vol s2-69 (275) ◽  
pp. 519-554
Author(s):  
H. G. NEWTH
Keyword(s):  
Early Development ◽  
Normal Development ◽  
Bilateral Symmetry ◽  
Mechanical Deformation ◽  
Insufficient Evidence ◽  
Vertebrate Embryos ◽  
Pore Canals

I. (1) The normal development of Astropecten irregularis is described up to the twenty-fifth day. (2) About a third of the larvae possessed two pore-canals, and larval twinning was observed in two cases. II. There is insufficient evidence for believing that normal Echinoderm larvae possess a ‘latent’ bilateral symmetry. III. The following provisional conclusions are reached regarding duplicity in Echinoderm larvae: (1) The various kinds of duplicity form a series. (2) They are of the same nature as those found in vertebrate embryos, and are probably due to similar causes. (3) They may be determined by (a) Alteration of the polarity of the egg ; (b) Interference with processes of early development affecting gastrulation ; (c) Physiological inhibition or mechanical deformation of the tip of the archenteron. (4) Their ultimate facies, in the case of (c), is determined largely by excess or defect of nutrition.

Hemoglobin crystals of the red blood cells in the human renal cortex: electron microscopic observations of the renal lithiasis

1978 ◽  
Vol 36 (2) ◽  
pp. 480-481
Author(s):  
Kosuke Ueda ◽  
Hiroto Washida ◽  
Nakazo Watari
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Renal Cortex ◽  
Uranyl Acetate ◽  
Osmic Acid ◽  
Renal Lithiasis ◽  
Electron Microscopic ◽  
Hemoglobin C ◽  
First Case ◽  
Ultrathin Sections

IntroductionHemoglobin crystals in the red blood cells were electronmicroscopically reported by Fawcett in the cat myocardium. In the human, Lessin revealed crystal-containing cells in the periphral blood of hemoglobin C disease patients. We found the hemoglobin crystals and its agglutination in the erythrocytes in the renal cortex of the human renal lithiasis, and these patients had no hematological abnormalities or other diseases out of the renal lithiasis. Hemoglobin crystals in the human erythrocytes were confirmed to be the first case in the kidney.Material and MethodsTen cases of the human renal biopsies were performed on the operations of the seven pyelolithotomies and three ureterolithotomies. The each specimens were primarily fixed in cacodylate buffered 3. 0% glutaraldehyde and post fixed in osmic acid, dehydrated in graded concentrations of ethanol, and then embedded in Epon 812. Ultrathin sections, cut on LKB microtome, were doubly stained with uranyl acetate and lead citrate.

Electron-diffraction studies in synthetic polymer materials

1983 ◽  
Vol 41 ◽  
pp. 362-365
Author(s):  
D.T. Grubb
Keyword(s):  
Electron Diffraction ◽  
Synthetic Polymer ◽  
Polymer Materials ◽  
Crystallographic Structure ◽  
High Dose ◽  
Electron Dose ◽  
Dose Rates ◽  
First Case ◽  
Diffraction Patterns ◽  
The Many

Diffraction studies in polymeric and other beam sensitive materials may bring to mind the many experiments where diffracted intensity has been used as a measure of the electron dose required to destroy fine structure in the TEM. But this paper is concerned with a range of cases where the diffraction pattern itself contains the important information.In the first case, electron diffraction from paraffins, degraded polyethylene and polyethylene single crystals, all the samples are highly ordered, and their crystallographic structure is well known. The diffraction patterns fade on irradiation and may also change considerably in a-spacing, increasing the unit cell volume on irradiation. The effect is large and continuous far C94H190 paraffin and for PE, while for shorter chains to C 28H58 the change is less, levelling off at high dose, Fig.l. It is also found that the change in a-spacing increases at higher dose rates and at higher irradiation temperatures.

Electron Microscopy of Silicon Deposits in Foliar Idioblasts of Magnolia Grandiflora

1976 ◽  
Vol 34 ◽  
pp. 374-375
Author(s):  
Michael T. Postek
Keyword(s):  
Electron Microscopy ◽  
Water Loss ◽  
Normal Development ◽  
Magnolia Grandiflora ◽  
Plant Body ◽  
Normal Metabolism ◽  
Hydrated Oxide

Silicon occurs naturally in plants in the form of its hydrated oxide (SiO2.nH2O) commonly called silica. Silica has been shown to be a necessary element in the normal development of many plants, playing an array of roles including strengthening, protection, and reduction of water loss. Deposition of silica in various portions of the plant body, especially the leaves, may also be viewed as a way for the plant to dispose of any excess silica taken up beyond that necessary for normal metabolism.Studies of this “opaline” silica have thus far been limited to species of the Cyperaceae and Gramineae known to possess significant quantities of silica. Within the Magnoliaceae, certain “glistening” idioblast cells at the foliar veinlet termini and vein sheaths of Magnolia grandiflora (1) have been suspected to be siliceous in nature.

Small-Angle Electron Scattering (SAES) of Polymers

1985 ◽  
Vol 43 ◽  
pp. 78-79
Author(s):  
Ralph Oralor ◽  
Pamela Lloyd ◽  
Satish Kumar ◽  
W. W. Adams
Keyword(s):  
Electron Scattering ◽  
Small Angle ◽  
Angular Resolution ◽  
Structural Features ◽  
Objective Lens ◽  
High Angular Resolution ◽  
Push Button ◽  
First Case ◽  
Diffraction Mode ◽  
Very High

Small angle electron scattering (SAES) has been used to study structural features of up to several thousand angstroms in polymers, as well as in metals. SAES may be done either in (a) long camera mode by switching off the objective lens current or in (b) selected area diffraction mode. In the first case very high camera lengths (up to 7Ø meters on JEOL 1Ø ØCX) and high angular resolution can be obtained, while in the second case smaller camera lengths (approximately up to 3.6 meters on JEOL 1Ø ØCX) and lower angular resolution is obtainable. We conducted our SAES studies on JEOL 1ØØCX which can be switched to either mode with a push button as a standard feature.

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