Self-Inhibition of Growth in Rana pipiens Tadpoles

1966 ◽  
Vol 39 (4) ◽  
pp. 341-356 ◽  
Author(s):  
Gwynn Collins Akin
Keyword(s):  
Rana Pipiens ◽  
Inhibition Of Growth

The Inhibition of Growth in Crowded Rana pipiens Tadpoles

1958 ◽  
Vol 31 (2) ◽  
pp. 138-151 ◽  
Author(s):  
Christina Macgregor Richards
Keyword(s):  
Rana Pipiens ◽  
Inhibition Of Growth

Comparative Morphology of Intercellular Bridges Between Developing Germ Cells of the Ovary

1970 ◽  
Vol 28 ◽  
pp. 328-329
Author(s):  
J. R. Ruby ◽  
R. F. Dyer ◽  
R. G. Skalko ◽  
R. F. Gasser ◽  
E. P. Volpe
Keyword(s):  
Germ Cells ◽  
Rana Pipiens ◽  
Comparative Morphology ◽  
Dense Material ◽  
Individual Species ◽  
Microscope Examination ◽  
Electron Dense Material ◽  
Intercellular Bridges ◽  
Cytoplasmic Side ◽  
Intercellular Connections

An electron microscope examination of fetal ovaries has revealed that developing germ cells are connected by intercellular bridges. In this investigation several species have been studied including human, mouse, chicken, and tadpole (Rana pipiens). These studies demonstrate that intercellular connections are similar in morphology regardless of the species.Basically, all bridges are characterized by a band of electron-dense material on the cytoplasmic side of the tri-laminar membrane surrounding the connection (Fig.l). This membrane is continuous with the plasma membrane of the conjoined cells. The dense material, however, never extends beyond the limits of the bridge. Variations in the configuration of intercellular connections were noted in all ovaries studied. However, the bridges in each individual species usually exhibits one structural characteristic seldom found in the others. For example, bridges in the human ovary very often have large blebs projecting from the lateral borders whereas the sides of the connections in the mouse gonad merely demonstrate a slight convexity.

The application of video-enhanced constrast/differential interference constrast microscopy in conjunction with whole mount electron microscopy to the study of organelle transport

1988 ◽  
Vol 46 ◽  
pp. 66-67
Author(s):  
J. H. Hayden
Keyword(s):  
Electron Microscopy ◽  
Rana Pipiens ◽  
Silver Film ◽  
Immunofluorescence Microscopy ◽  
Organelle Transport ◽  
Linear Element ◽  
Whole Mount ◽  
Carbon Coated ◽  
Linear Elements ◽  
Dic Microscopy

In a previous study, Allen video-enhanced constrast/differential interference constrast (AVEC-DIC) microscopy was used in conjunction with immunofluorescence microscopy to demonstrate that organelles and vesicle move in either direction along linear elements composed of microtubules. However, this study was limited in that the number of microtubules making up a linear element could not be determined. To overcome this limitation, we have used AVEC-DIC microscopy in conjunction with whole mount electron microscopy.Keratocytes from Rana pipiens were grown on glass coverslips as described elsewhere. Gold London Finder grids were Formvar- and carbon coated, and sterilized by exposure to ultraviolet light. It is important to select a Formvar film that gives a grey reflection when it is floated on water. A silver film is too thick and will detract from the image in the light microscope.

DIFFERENCES IN GROWTH AND THYROID FUNCTION OF PEKIN AND MUSCOVY DUCKS EITHER UNTREATED OR TREATED WITH STILBOESTROL

1965 ◽  
Vol 50 (3) ◽  
pp. 411-417 ◽  
Author(s):  
Hans von Faber ◽  
Wolfgang Häussermann
Keyword(s):  
Thyroid Function ◽  
Pekin Ducks ◽  
Inhibition Of Growth ◽  
Marked Inhibition ◽  
Muscovy Ducks ◽  
Effect On Growth

ABSTRACT Pekin ducks grow faster and show a faster and higher thyroidal 131I uptake than Muscovy ducks. Treatment with a total of 15 mg stilboestrol during the first 4 weeks had no effect on growth, thyroid weight or thyroidal 131I uptake in male or female Pekin ducklings. In male Muscovy ducklings the same treatment caused a marked inhibition of growth, a decrease in thyroid weight and a lowered thyroidal 131I uptake. Thyroxine, administered simultaneously in physiological doses, did not prevent inhibition of growth. It is therefore concluded that this inhibition is not due to the lowered thyroid function.

ROLE OF THE THYROID GLAND IN DEVELOPMENT AND MAINTENANCE OF RENAL HYPERTENSION IN RATS

1960 ◽  
Vol XXXIV (III) ◽  
pp. 411-429 ◽  
Author(s):  
Melvin J. Fregly ◽  
Kenneth M. Cook
Keyword(s):  
Blood Pressure ◽  
Rate Increase ◽  
Renal Hypertension ◽  
The Other ◽  
Elevated Blood Pressure ◽  
Unit Weight ◽  
Elevated Blood ◽  
Inhibition Of Growth ◽  
Testicular Size

ABSTRACT The anti-thyroid drugs, thiouracil, propylthiouracil, and methimazole, prevented both development of elevated blood pressure and cardiac hypertrophy usually accompanying kidney encapsulation with latex envelopes. These drugs also reduced elevated blood pressure of rats with hypertension of 13 to 40 weeks' duration prior to drug administration. Addition of desiccated thyroid powder to diet containing an anti-thyroid drug overcame the anti-hypertensive effect of the latter. Withdrawal of thyroid powder only was followed by return of blood pressure to previous low level within 3 weeks. The results suggest that the anti-hypertensive effect of these drugs is related directly to the hypothyroidism produced rather than to extrathyroidal effects of the drugs. Comparison of potencies of the 3 drugs in terms of anti-hypertensive effect, inhibition of growth rate, increase in testicular size, and increase in thyroid size suggests that propylthiouracil and methimazole are equally potent per unit weight of drug. Thiouracil has approximately half the potency of the other two.

FEEDBACK OF WATER STRESS ON WOOD PROPERTIES OF TREES: EXPERIMENTS WITH MISTLETOES ON RHODODENDRON ARBOREUM SM.

1970 ◽  
Vol 11 (1) ◽  
Author(s):  
Mohan P. Devkota ◽  
Gerhard Glatzel
Keyword(s):  
Water Stress ◽  
Wood Anatomy ◽  
Wood Properties ◽  
Vessel Diameter ◽  
Conservation Area ◽  
Rhododendron Arboreum ◽  
Central Nepal ◽  
Inhibition Of Growth ◽  
Infected Area ◽  
Anatomical Parameters

Effects of infection by the mistletoe Scurrula elata (Edgew.) Danser, on wood properties of its common host Rhododendron arboreum Sm., were studied in the Annapurna Conservation Area of Central Nepal Himalaya. Heavy infection by mistletoes invariably causes decline of the host. Infested branches show inhibition of growth, defoliation and eventual death of branch parts distal to the site of infection. Anatomical properties of wood were compared in samples of branches proximal to the infection and in uninfected branches. The hypothesis that infection induces changes in basic wood anatomy could not be proven. Vessel density, vessel area, percentage lumen area and mean vessel diameter of the wood of infested and uninfected branches did not show any significant differences. The studied anatomical parameters were not correlated to the diameter of the host branch. These results show that infection by S. elata did not cause any changes in basic wood anatomy of its host R. arboreum. It appears that the studied anatomical parameters of Rhododendron wood are fairly stable and are not changed by stress due to infection by mistletoes. The damage to the host distal to the infected area most likely results from an insufficiency of total conductive area to supply both mistletoe and host. Unfortunately we could not determine annual conductive area increment, because R arboreum does not develop usable annual tree rings in the climate of the study area. Key words: Himalayas, mistletoe. Rhododendron arboreum, Scurrula elata, water stress, wood anatomy. Ecoprint Vol.11(1) 2004.

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