Transmission electron micrograph of section through the macronucleus of Nassula sp containing many darkly staining nucleoli.

Food vacuole and macronucleus of Didinium. The food vacuole contains unexploded trichocysts of Paramecium. Further details available at Wessenberg, H. and Antipa, G. 1968. Studies on Didinium nasutum....

A low power view of a median transverse section of a green Trichodina that lives on the surface of a freshwater snail collected in central Illinois. In this view the abundant endosymbiotic zoochlorell...

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 pro...

Grazing thin section through the nuclear envelope of a macronucleus. Nuclear pores are packed so tightly that they often form a hexagonal array with 6 pores surrounding a central pore. The pores often...

High resolution overview of Coleps hirtus cell seen in this median transverse section. This barrel-shaped cell has a few rows of cilia and the cell is covered with calcified polysaccharide platelets t...

Opercularia is named for a ciliated flap (operculum) that is adoral to the opening to the oral region. However, this operculum is pulled back into the body when the myonemes are fully contracted as in...

A high resolution overview of Opercularia coarctata showing that cytostome divides the peristome from the cytopharynx. The cytopharynx starts where the alveoli end in the oral region. TEM taken on 6/1...

The cytostome of Opercularia divides the peristome from the cytopharynx. The cytopharynx starts where the alveoli end in the oral region. TEM taken on 6/13/69 by R. Allen with Philips 300 operating at...

This image of Halteria was fixed in cacodylate-buffered fixative and stained. The round, dark bodies, possibly pigment granules, were transparent in other preparations are electron-opaque following th...