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High resolution image of the nucleoli of the macronucleus. Nucleoli have a core of DNA that contains the genes that are transcribed into ribosomal RNA. Assembly of the ribosomal subunits from this processed RNA and from proteins transported into the nucleus through the pores occurs in the nucleoli. A concentric stack of rough ER encircles a mitochondrion. TEM taken on 8/16/67 by R. Allen with Philips 200 operating at 60kV. Neg. 7,200X. The raw film was scanned with an Epson Perfection V750 Pro. This image is best used for quantitative analysis.

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. Additional information available at (

Biological Sources

NCBI Organism Classification
Tetrahymena pyriformis
Cell Type
cell by organism
eukaryotic cell
Eukaryotic Protist
Ciliated Protist
Cellular Component
nucleolus organizer region

Biological Context

Biological Process
macronucleus organization
nucleolus 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 6050px 2.0nm
Y 5003px 2.0nm
*CIL – Cell Image Library accession number. Please use this to reference an image.