scholarly journals Segregation of germline granules in early embryos of Caenorhabditis elegans: an electron microscopic analysis

Development ◽  
1983 ◽  
Vol 73 (1) ◽  
pp. 297-306
Author(s):  
Nurit Wolf ◽  
James Priess ◽  
David Hirsh
Keyword(s):  
Electron Microscopy ◽  
Caenorhabditis Elegans ◽  
Microscopic Analysis ◽  
Precursor Cell ◽  
Electron Microscopic Analysis ◽  
Fixation Method ◽  
Electron Microscopic ◽  
Early Embryos ◽  
Germline Cells

Using an improved fixation method for electron microscopy, we have found germline granules in Caenorhabditis elegans embryos shortly after fertilization and prior to the first cleavage. They are localized in the egg cytoplasm which becomes segregated into the posterior blastomere at the first cleavage. In the following divisions, the granules continue this pattern of asymmetric segregation and are ultimately segregated into the germline precursor cell. The granules are then symmetrically segregated into the germline cells.

Bridging the Resolution Gap: Correlated 3D Light and Electron Microscopic Analysis of Large Biological Structures

1999 ◽  
Vol 5 (S2) ◽  
pp. 526-527
Author(s):  
Maryann E. Martone
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Surface Area ◽  
Light Microscope ◽  
Microscopic Analysis ◽  
Electron Microscopic Analysis ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Biological Structures ◽  
Ganglion Neurons

One class of biological structures that has always presented special difficulties to scientists interested in quantitative analysis is comprised of extended structures that possess fine structural features. Examples of these structures include neuronal spiny dendrites and organelles such as the Golgi apparatus and endoplasmic reticulum. Such structures may extend 10's or even 100's of microns, a size range best visualized with the light microscope, yet possess fine structural detail on the order of nanometers that require the electron microscope to resolve. Quantitative information, such as surface area, volume and the micro-distribution of cellular constituents, is often required for the development of accurate structural models of cells and organelle systems and for assessing and characterizing changes due to experimental manipulation. Performing estimates of such quantities from light microscopic data can result in gross inaccuracies because the contribution to total morphometries of delicate features such as membrane undulations and excrescences can be quite significant. For example, in a recent study by Shoop et al, electron microscopic analysis of cultured chick ciliary ganglion neurons showed that spiny projections from the plasmalemma that were not well resolved in the light microscope effectively doubled the surface area of these neurons.While the resolution provided by the electron microscope has yet to be matched or replaced by light microscopic methods, one drawback of electron microscopic analysis has always been the relatively small sample size and limited 3D information that can be obtained from samples prepared for conventional transmission electron microscopy. Reconstruction from serial electron micrographs has provided one way to circumvent this latter problem, but remains one of the most technically demanding skills in electron microscopy. Another approach to 3D electron microscopic imaging is high voltage electron microscopy (HVEM). The greater accelerating voltages of HVEM's allows for the use of much thicker specimens than conventional transmission electron microscopes.

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