Fig. 1.

Various nuclei to illustrate the enormous range in DNA content of different cell types. All stained with 4’,6-diamidino-2-phenylindole (DAPI), whose intensity is proportional to the amount of DNA. A and C are from stacks of confocal images, showing only part of the specimen. B is a conventional image of a relatively flat specimen. A) A small oocyte from the axolotl Ambystoma mexicanum surrounded by diploid follicle cells. The axes of the LBCs are visible as DAPI-positive rows of chromomeres, but the loops are not detectable with this stain. The chromosomes contain only the 4C amount of DNA, despite the large size of the GV. B) A giant lobulated nucleus from a Malpighian tubule of the caterpillar Pseudoplusia sp. The inset at the upper left shows a group of presumably diploid nuclei from a nearby field. The ploidy level of the giant nucleus is probably in the tens of thousands. C) An egg chamber of Drosophila melanogaster showing the small GV with transcriptionally inactive chromatin (4C DNA content) and seven of the 15 highly polyploid nurse cell nuclei (up to ~4000C DNA content). Essentially all of the transcripts of the oocyte are derived from the nurse cell nuclei. Image provided by Zehra Nizami.