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

CIL:12300*  Cite 

Didinium (non-dividing) has a massive cytopharynx at its anterior end that takes the shape of a cone-shaped proboscis when closed. This cytopharynx contains numerous lamellae composed of sets of microtubules that lie perpendicular to each other next to the cytopharyngeal membrane. Vesicles containing a uniform medium dense material (mucocysts?), line up between the lamellae. Presumably these vesicles fuse with the single cytopharyngeal membrane that covers the lamellae. Extrusomes called toxicysts lie within in the cytopharyngeal region. TEM taken on 9/19/68 by R. Allen with Philips 300 operating at 60kV. Neg. 10,300X. Bar = 0.5µm. The negative was printed to paper and the image was scanned to Photoshop. This digitized image is available for qualitative analysis. A high resolution version is available for quantitative analysis (CIL:38861). 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
Didinium nasutum
Cell Type
cell by organism
eukaryotic cell
Eukaryotic Protist
Ciliated Protist
Cell Line
Carolina Biological Supply Company, NC, U.S.A.
Cellular Component
cell cortex
cortical microtubule cytoskeleton
mucus extrusomes
toxic extrusomes
Richard Allen
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 to Photoshop.
Data Qualifiers
processed data
suitable for spatial measurements
Spatial Axis Image Size Pixel Size
X 2814px ——
Y 3384px ——