Low-temperature scanning electron microscopic observations on endosperm in imbibed and germinated lettuce seeds

1998 ◽  
Vol 76 (3) ◽  
pp. 509-516 ◽  
Author(s):  
J Nijsse ◽  
E Erbe ◽  
NBM Brantjes ◽  
JHN Schel ◽  
W P Wergin
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Polyethylene Glycol ◽  
Low Temperature ◽  
Lactuca Sativa ◽  
Electron Microscopic ◽  
Lettuce Seeds ◽  
Temperature Scanning ◽  
Germinating Seeds ◽  
Scanning Electron

Lettuce (Lactuca sativa L.) seeds were observed using low-temperature scanning electron microscopy (LTSEM). The structure of imbibing and germinating seeds was characterized and compared with that of seeds in which these processes were inhibited by high temperature, far-red irradiation, or polyethylene glycol. Germination is not associated with general breakdown or digestion of the entire endosperm at the micropylar region. Embryos of seeds imbibed in polyethylene glycol, which inhibited germination, appeared to lack turgor and were not able to emerge from the endosperm. Thermal or far-red inhibitory treatments were associated with the appearance of complex membraneous structures in cells of the endosperm and the embryo.Key words: endosperm, germination, Lactuca sativa, lettuce, low temperature scanning electron microscopy, seed.

Pores of Kohn are filled in normal lungs: low-temperature scanning electron microscopy

1992 ◽  
Vol 73 (1) ◽  
pp. 88-95 ◽  
Author(s):  
J. Bastacky ◽  
J. Goerke
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Low Temperature ◽  
Gas Diffusion ◽  
Normal Lung ◽  
Electron Microscopic ◽  
Normal Rat ◽  
Temperature Scanning ◽  
Microscopic Techniques ◽  
Scanning Electron

Interalveolar pores of Kohn, small uniform-sized epithelium-lined openings in alveolar walls of normal lung, have historically been demonstrated with electron-microscopic techniques that remove water. We show these pores to be present but almost invariably filled with material when water and surfactant are preserved in frozen hydrated lung examined with low-temperature scanning electron microscopy. In the normal mouse, 16 open empty pores per alveolus were found in instillation-fixed dried lung vs. less than 1 per alveolus in frozen hydrated lungs (P less than 0.001). In the normal rat, 13 pores were seen per alveolus in instillation-fixed dried lung vs. less than 1 per alveolus in frozen hydrated lungs (P less than 0.001). We suggest that pores of Kohn 1) function primarily as conduits for interalveolar movement of alveolar liquid, surfactant components, and macrophages, 2) provide distributed sites for tubular myelin storage without increasing gas diffusion pathway thickness in the alveolar subphase itself, and 3) do not function as pathways for collateral ventilation during normal breathing in the absence of atelectasis or obstruction.

Intracellular structures of rapid frozen biological samples observed by high-resolution low-temperature Scanning Electron Microscopy

1989 ◽  
Vol 47 ◽  
pp. 736-737
Author(s):  
T. Inoué ◽  
H. Koike
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Low Temperature ◽  
Liquid Nitrogen ◽  
Specimen Preparation ◽  
Chemical Fixation ◽  
Brown Adipose ◽  
Critical Point Drying ◽  
Temperature Scanning ◽  
Scanning Electron

Low temperature scanning electron microscopy (LTSEM) is useful to avoid artifacts such as deformation and extraction, because specimens are not subjected to chemical fixation, dehydration and critical-point drying. Since Echlin et al developed a LTSEM, many techniques and instruments have been reported for observing frozen materials. However, intracellular structures such as mitochondria and endoplasmic reticulum have been unobservable by the method because of the low resolving power and inadequate specimen preparation methods. Recently, we developed a low temperature SEM that attained high resolutions. In this study, we introduce highly magnified images obtained by the newly developed LTSEM, especially intracellular structures which have been rapidly frozen without chemical fixation.[Specimen preparations] Mouse pancreas and brown adipose tissues (BAT) were used as materials. After the tissues were removed and cut into small pieces, the specimen was placed on a cryo-tip and rapidly frozen in liquid propane using a rapid freezing apparatus (Eiko Engineering Co. Ltd., Japan). After the tips were mounted on the specimen stage of a precooled cryo-holder, the surface of the specimen was manually fractured by a razor blade in liquid nitrogen. The cryo-holder was then inserted into the specimen chamber of the SEM (ISI DS-130), and specimens were observed at the accelerating voltages of 5-8 kV. At first the surface was slightly covered with frost, but intracellular structures were gradually revealed as the frost began to sublimate. Gold was then coated on the specimen surface while tilting the holder at 45-90°. The holder was connected to a liquid nitrogen reservoir by means of a copper braid to maintain low temperature.

Criteria for the evaluation of low-temperature Scanning Electron Microscopy

1986 ◽  
Vol 44 ◽  
pp. 902-903
Author(s):  
Alan Beckett
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Low Temperature ◽  
Conformational Changes ◽  
Chemical Vapour ◽  
List Type ◽  
Dimensional Changes ◽  
Critical Point Drying ◽  
Temperature Scanning ◽  
Scanning Electron

Low temperature scanning electron microscopy (LTSEM) has been evaluated with special reference to its application to the study of morphology and development in microorganisms. A number of criteria have been considered and have proved valuable in assessing the standard of results achieved. To further aid our understanding of these results, it has been necessary to compare those obtained by LTSEM with those from more conventional preparatory procedures such as 1) chemical fixation, dehydration and critical point-drying; 2) freeze-drying with or without chemical vapour fixation before hand.The criteria used for assessing LTSEM for the above purposes are as follows: 1)Specimen immobilization and stabilization2)General preservation of external morphology3)General preservation of internal morphology4)Exposure to solvents5)Overall dimensional changes6)Cell surface texture7)Differential conformational changes8)Etching frozen-hydrated material9)Beam damage10)Specimen resolution11)Specimen life

scholarly journals Low-temperature scanning electron microscopy in fungus-nematode interaction

Scanning ◽  
1993 ◽  
Vol 15 (1) ◽  
pp. 37-42 ◽  
Author(s):  
E. Den Belder ◽  
A. Boekestein ◽  
J. W. J. Van Esch ◽  
F. Thiel
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Low Temperature ◽  
Temperature Scanning ◽  
Scanning Electron
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