Alternate header for print version

Public Domain: This image is in the public domain and thus free of any copyright restrictions. However, as is the norm in scientific publishing and as a matter of courtesy, any user should credit the content provider for any public or private use of this image whenever possible. Learn more
*CIL – Cell Image Library accession number. Please use this to reference an image.

CIL:36650*  Cite 

Except that the nuclear envelope remains intact, micronuclear mitosis occurs in a normal way passing through the four stages of prophase, metaphase, anaphase and telophase. In this example a micronucleus was sectioned in early anaphase and shows condensed daughter chromosomes at each pole. Chromosomes are separated by a large bundle of microtubules making up an intranuclear spindle. The separation spindle will become a very long thin tube (see Fig.20 in Allen, Ueno and Fok, J. Protozool. 35:400-407, 1988). The image shown here has very low contrast because the cell was taken from a culture in which a 15 minute treatment in ammonium chloride was used to see what effect this base would have on its acidic compartments. The cell was then incubated in diaminobenzidine. As usual the cristae of mitochondria become electron-opaque following this treatment. TEM taken on 6/11/86 by R. Allen with Zeiss 10A operating at 80kV. Neg. 4,000X. Bar = 1µm.

Technical Details

Standard glutaraldehyde fixation followed by osmium tetroxide, dehydrated in alcohol and embedded in an epoxy resin. Microtome sections prepared at approximately 75nm thickness. The negative was printed to paper and the image was scanned to Photoshop. This digitized image is available for qualitative analysis. Additional information available at (

Biological Sources
NCBI Organism Classification
Paramecium multimicronucleatum
Cell Type
cell by organism
eukaryotic cell
Eukaryotic Protist
Ciliated Protist
Cellular Component
Biological Context
Biological Process
nuclear division
Richard Allen (University of Hawaii)
Digital Object Identifier (DOI)
Archival Resource Key (ARK)
Image Type
transmission electron microscopy (TEM)
illumination by electrons
Image Mode
detection of electrons
Parameters Imaged
electron density
Source of Contrast
stain with broad specificity
Visualization Methods
stain with broad specificity
uranyl salt
lead salt
osmium tetroxide
Processing History
recorded image
Print from negative scanned for Photoshop.
Data Qualifiers
processed data
Spatial Axis Image Size Pixel Size
X 3000px ——
Y 2832px ——