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Nucleoli in a macronucleus of a cell undergoing micronuclear division. The nucleolus appears to have an organized surface layer composed of parallel threads of subunits. These may be developing ribosomal subunits that will soon be transported to the cytoplasm through the nuclear pores. TEM taken on 3/30/73 by R. Allen with Hitachi HU11A operating at 75kV. Neg. 15,759X.

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 raw negative was scanned with an Epson Perfection V750 Pro and this high resolution image is best used for quantitative analysis. Additional information available at (

Biological Sources

NCBI Organism Classification
Paramecium caudatum
Cell Type
cell by organism
eukaryotic cell
Eukaryotic Protist
Ciliated Protist
Cellular Component
nuclear pore

Biological Context

Biological Process
macronucleus organization


Richard Allen (University of Hawaii)


This image is part of a group.
Data Qualifiers
raw, unprocessed data
suitable for spatial measurements


Spatial Axis Image Size Pixel Size
X 4572px 0.95nm
Y 5116px 0.95nm
*CIL – Cell Image Library accession number. Please use this to reference an image.