Fine structure and X-ray microanalysis of mineralized concretions in the Malpighian tubules of the housefly, Musca domestica

An ultrastructural investigation of the Malpighian tubules of the fourth instar larva of Culex pipiens was undertaken as part of a continuing study of the fine structure of transport epithelia.Each of the five Malpighian tubules was found to be morphologically identical and regionally undifferentiated. Two distinct cell types, the primary and stellate, were found intermingled along the length of each tubule. The ultrastructure of the stellate cell was previously described in the Malpighian tubule of the blowfly, Calliphora erythrocephala by Berridge and Oschman.The basal plasma membrane of the primary cell is extremely irregular, giving rise to a complex interconnecting network of basal channels. The compartments of cytoplasm entrapped within this system of basal infoldings contain mitochondria, free ribosomes, and small amounts of rough endoplasmic reticulum. The mitochondria are distinctive in that the cristae run parallel to the long axis of the organelle.

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Extended Core Edge Fine Structure in the E.M.

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600000489 ◽

1980 ◽

Vol 38 ◽

pp. 120-121

Author(s):

R.D. Leapman

Keyword(s):

Fine Structure ◽

Electron Scattering ◽

Inelastic Electron ◽

High Resolution Imaging ◽

X Ray ◽

Analytical Electron ◽

Analytical Electron Microscope ◽

Core Electrons ◽

Resolution Imaging ◽

X Ray Absorption

Extended X-ray Absorption Fine Structure (EXAFS) analysis makes use of synchrotron radiaion to measure modulations in the absorption coefficient above core edges and hence to obtain information about local atomic environments. EXAFS arises when ejected core electrons are backscattered by surrounding atoms and interfere with the outgoing waves. Recently, interest has also been shown in using inelastic electron scattering1-4. Some advantages of Extended X-ray-edge Energy Loss Fine Structure (EXELFS) are: a) small probes formed by the analytical electron microscope give spectra from μm to nm sized areas, compared with mm diameter areas for the X-ray technique, b) EXELFS can be combined with other techniques such as electron diffraction or high resolution imaging, and c) EXELFS is sensitive to low Z elements with K edges from ˜200 eV to ˜ 3000 eV (B to Cl).

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Some Aspects of Exelfs Analysis in the Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600000477 ◽

1980 ◽

Vol 38 ◽

pp. 118-119

Author(s):

D. E. Johnson ◽

S. Csillag

Keyword(s):

Fine Structure ◽

Electron Microscope ◽

Energy Loss ◽

Analytical Electron Microscopy ◽

Interference Effects ◽

Interatomic Distances ◽

X Ray ◽

Structure Information ◽

Microanalytical Technique ◽

Analytical Electron

Recently, the applications area of analytical electron microscopy has been extended to include the study of Extended Energy Loss Fine Structure (EXELFS). Modulations past an ionization edge in the energy loss spectrum (EXELFS), contain atomic fine structure information similar to Extended X-ray Absorbtion Fine Structure (EXAFS). At low momentum transfer the main contribution to these modulations comes from interference effects between the outgoing excited inner shell electron waves and electron waves backscattered from the surrounding atoms. The ability to obtain atomic fine structure information (such as interatomic distances) combined with the spatial resolution of an electron microscope is unique and makes EXELFS an important microanalytical technique.

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