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*CIL – Cell Image Library accession number. Please use this to reference an image.

CIL:36790*  Cite 

The cytoproct is the cell’s defecation site where spent digestive vacuoles fuse with the plasma membrane. In this cell the cytoproct is closed and forms a ridge along the posterior suture on the ventral side of the cell. The ridge contains distinctive fibers not found in other parts of the cell. It is covered on its sides by alveoli but has a single membrane over the crest of the ridge. The somatic basal bodies on both sides of the ridge give rise to microtubular bundles that extend into the endoplasm where they lie against the surface of approaching spent vacuoles (DV-IV). The spent vacuole has tubular extensions protruding from its membrane. TEM taken on 4/13/73 by R. Allen with Hitachi HU11A operating at 75kV. Neg. 13,250X. Bar = 0.5µm. Adapted with permission.

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. There is a high resolution version of this image in the library (CIL:39181) which is available 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
microtubule associated complex
cell cortex
vesicle membrane
Richard Allen (University of Hawaii)
J Cell Sci. 1974 May;14(3):611-31.
Digital Object Identifier (DOI)
Archival Resource Key (ARK)
Grouping This image is part of a group.
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 1560px ——
Y 1756px ——