scholarly journals A FINE STRUCTURAL ANALYSIS OF CLEAVAGE INDUCTION AND FURROWING IN THE EGGS OF ARBACIA PUNCTULATA

1969 ◽  
Vol 42 (1) ◽  
pp. 170-184 ◽  
Author(s):  
Lewis G. Tilney ◽  
Douglas Marsland
Keyword(s):  
High Pressure ◽  
Fine Structure ◽  
Essential Role ◽  
Annulate Lamellae ◽  
Cleavage Division ◽  
Arbacia Punctulata ◽  
Naturally Occurring ◽  
Tentative Hypothesis ◽  
Normal Division ◽  
Experimentally Induced

A fine structural study has been carried out on the various formed elements present before, during, and after the first cleavage division, not only in normally developing Arbacia eggs, but also in eggs which have been induced to cleave prematurely by high-pressure centrifugation. The aim has been to ascertain whether or not any of the morphologically identifiable components may be involved in initiating the furrowing process. Also, attention has been given to the fine structure of the cytoplasmic cortex, particulary in the walls of the furrow, in the hope of reaching a better understanding of the mechanics of cleavage. The annulate lamellae and the membranous envelope of the nucleus are the only formed elements which disappear shortly before cleavage, not only in eggs undergoing normal division, but also in eggs which have been induced to cleave ahead of schedule by high-pressure, high-force centrifugation. Therefore, it is suggested as a tentative hypothesis that materials liberated upon disintegration of the nuclear membrane and the annulate lamellae play an essential role in initiating and effecting the furrowing reaction, especially since the stratification of these elements in experimentally induced eggs corresponds to the position of the developing furrow. Another of the membranous elements in the egg, the Golgi complex, shows considerable modification as a result of high-pressure centrifugation, but these structures do not undergo disintegration. Rather, they become curled into rounded bodies. The vacuole population is not greatly affected by inducing treatments. During cleavage, both naturally occurring and experimentally induced, a considerable number of 50 A filaments appear in the denser cytoplasmic cortex, but only in the walls of the furrow. These filaments are similar to those which have been demonstrated in a number of contractile cells. Accordingly, it is suggested that this fibrillar system may be actively involved in the development of the cleavage force.

scholarly journals Genetic Evidence for an Essential Role of Neuronally Expressed IL-6 Signal Transducer gp130 in the Induction and Maintenance of Experimentally Induced Mechanical Hypersensitivityin vivoandin vitro

2011 ◽  
Vol 7 ◽  
pp. 1744-8069-7-73 ◽  
Author(s):  
Serena Quarta ◽  
Christian Vogl ◽  
Cristina E Constantin ◽  
Nurcan Üçeyler ◽  
Claudia Sommer ◽  
...  
Keyword(s):  
Essential Role ◽  
Genetic Evidence ◽  
Signal Transducer ◽  
Experimentally Induced

Studies in fleece-rot of sheep.

1953 ◽  
Vol 4 (4) ◽  
pp. 430 ◽  
Author(s):  
RH Hayman
Keyword(s):  
Microscopic Examination ◽  
Similar Condition ◽  
Unit Area ◽  
Skin Surface ◽  
Climatic Conditions ◽  
Field Station ◽  
Merino Sheep ◽  
Naturally Occurring ◽  
Sufficient Intensity ◽  
Experimentally Induced

Occasions of unduly heavy and prolonged rainfall during the period April 1946 – July 1951 resulted in the occurrence of fleece-rot in sheep of the Field Station flock in each of the six years. Data obtained from periodic examinations of the flock have been related to the nature of climatic conditions associated with outbreaks of the disease. They show that when rain occurs in falls of sufficient intensity and frequency to wet sheep to the skin for a period of a week or more, fleece-rot may be expected to develop in some of them. The longer the period for which the sheep are kept wet, the greater the number in a flock which will be affected. Fleece-rot was experimentally induced in four out of five Merino sheep known to be susceptible to the condition, whereas five animals known to be resistant were unaffected by the same treatment. Microscopic examination of skin sections taken from naturally occurring cases revealed the presence of a dermatitis. A similar condition was observed in skin sections from the animals in which fleece-rot was experimentally induced. Young sheep were found to be more susceptible than old. There was no association between degree of wrinkling and susceptibility or between 'grip' and susceptibility. When subjectively-appraised attributes of the fleece were related to the occurrence of fleece-rot, confusing results were obtained. However, when measured fleece data, obtained from a group of Merino sheep which had been under observation for four consecutive years, were considered, it was found that those for clean-scoured yield, wax and suint ratio, and density of fibre population per unit area of skin surface, were related to resistance or susceptibility. Nevertheless, a number of animals were found which were susceptible or resistant to the disease despite the nature of their fleece attributes. Differences in susceptibility were found between families of Merino sheep. These are associated with between-family differences for the fleece attributes found to be important in fleece-rot reaction.

Extended x-ray-absorption fine-structure study of copper under high pressure

1989 ◽  
Vol 39 (17) ◽  
pp. 12537-12547 ◽  
Author(s):  
J. Freund ◽  
R. Ingalls ◽  
E. D. Crozier
Keyword(s):  
High Pressure ◽  
Fine Structure ◽  
Structure Study ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption

Fine structure of prolactin pituitary adenoma with special reference to annulate lamellae

1979 ◽  
Vol 46 (1-2) ◽  
pp. 163-166 ◽  
Author(s):  
M. Scanarini ◽  
R. Giordano ◽  
S. Mingrino ◽  
N. Pennelli
Keyword(s):  
Fine Structure ◽  
Pituitary Adenoma ◽  
Special Reference ◽  
Annulate Lamellae

scholarly journals FURTHER OBSERVATIONS ON THE FINE STRUCTURE OF THE MACRONUCLEUS IN TOKOPHRYA INFUSIONUM

1956 ◽  
Vol 2 (4) ◽  
pp. 425-430 ◽  
Author(s):  
Maria A. Rudzinska
Keyword(s):  
Fine Structure ◽  
Three Dimensional ◽  
Honeycomb Structure ◽  
Three Dimensional Reconstruction ◽  
Great Abundance ◽  
Dimensional Reconstruction ◽  
Experimentally Induced

In a previous paper (8) an organized structure was described in the macronuclei of certain old organisms of Tokophrya infusionum. It was found that the same honeycomb structure appears in great abundance in the macronuclei of overfed organisms. This permitted a better three-dimensional reconstruction of the described structure. Since the defined structure may be experimentally induced, it offers an opportunity for further more detailed studies as to its nature and meaning.

Vibrational Dephasing and Collision Induced Scattering in Molecular Liquids

1983 ◽  
Vol 22 ◽  
Author(s):  
Jiri Jonas
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Temperature Effects ◽  
Essential Role ◽  
Theoretical Models ◽  
Molecular Liquids ◽  
Vibrational Dephasing

ABSTRACTThe results of several Raman studies of vibrational dephasing in polyatomic molecular liquids at high pressure are reviewed. The density and temperature effects on vibrational dephasing of isotropic Raman bands for different vibrational models are reported for the following liquids: C(CH3)4; Si(CH3)4; Ge(CH3)4; ; Sn(CH3)4 and isobutylene CH2; = C(CH3) 2.The experimental data are used to test the current theoretical models of vibrational dephasing. Selected results of our high pressure experiments on collision induced scattering in polyatomic molecular liquids demonstrate well the essential role of high pressure in studying these phenomena.

Comparison of Experimentally Induced and Naturally Occurring Sensitivity to Leucine Hypoglycemia1

1963 ◽  
Vol 23 (6) ◽  
pp. 579-587 ◽  
Author(s):  
RALPH F. KNOPF ◽  
STEFAN S. FAJANS ◽  
JOHN C. FLOYD ◽  
JEROME W. CONN
Keyword(s):  
Naturally Occurring ◽  
Experimentally Induced
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