A micrograph showing the polyploidal macronucleus of Tetrahymena containing many copies of the genome. Chromatin material is found as condensed electron opaque spots as well as in an uncondensed form between the opaque spots. The macronucleus, unlike the micronucleus, contains many nucleoli that tend to accumulate next to the nuclear envelope. Nucleoli are sites of ribosomal RNA synthesis and ribosome subunit assembly. TEM taken on 8/14/67 by R. Allen with Philips 200 operating at 60kV. Neg. 4,500X. The raw negative was scanned with an Epson Perfection V750 Pro and this high resolution image is best used for quantitative analysis. Additional information available at (http://www5.pbrc.hawaii.edu/allen/).