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

CIL:13131*  Cite 

The cytoproct is the site of spent vacuole defecation on the surface of Paramecium. When closed the cytoproct forms a long narrow wavy ridge along the posterior suture. At its apex the ridge is about 0.2µm wide and it can be as much as 12µm or more in length. This ridge has the ability to be pulled down against the approaching spent vacuole where the plasma membrane covering the midline of the ridge will meet and fuse with the membrane of the vacuole. The ridge contains unique fibers on both of its lips that mesh with each other as they meet inside the ridge (see Allen and Wolf, J. Cell Sci. 14:611-631, 1974). TEM taken on 4/19/79 by R. Allen with Hitachi HU11A operating at 60kV. Neg. 10,000X. Bar = 0.5µm. The negative was printed to paper and the image was scanned to Photoshop. This digitized image is available for qualitative analysis. An unprocessed, high resolution version of this image (CIL:12343) is in the library and available for quantitative analysis. 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
Paramecium multimicronucleatum
Cell Type
cell by organism
eukaryotic cell
Eukaryotic Protist
Ciliated Protist
Cellular Component
cell cortex
Biological Context
Biological Process
cortical cytoskeleton organization
Richard Allen (University of Hawaii)
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
osmium tetroxide
uranyl salt
lead salt
Processing History
recorded image
Print from negative scanned for Photoshop.
Data Qualifiers
processed data
Spatial Axis Image Size Pixel Size
X 3053px ——
Y 3253px ——