They belong to a class of specialized chromosomes discovered in the oocytes of animals except for mammals. Walter Flemming discovered these specialized structures. They show the presence of highly extended regions. The tailed and the tailless amphibians, birds, and insects show these specialized chromosomes. These chromosomes do not occur in plants. The geneticists visualize the lampbrush chromosomes even under the light microscope. Hence, they involve an easy staining procedure. The lampbrush chromosomes exist as bivalents, each having two sister chromatids. These chromosomes get visualized mainly in the diplotene stage of prophase I of meiosis-l. During this stage, the chromosomes get converted into lampbrush shaped. Meaning, they resemble a brush for cleaning the chimneys. They consist of loops occurring in pairs. They occur as one on either side of the axis. These chromosomes involve active transcription. Mainly, the loops involve vigorous RNA synthesis. The basic units of lampbrush chromosomes include a pair of deoxyribonucleoprotein (DNP) fibers. They run along the axis of the chromosomes. However, the centromere of the lampbrush chromosome lacks the lateral loops. It is known as a chromomere. It gets flanked by the condensed regions showing the axial bars.

The axial bars include the pericentromeric heterochromatin. These regions show the presence of highly repetitive satellite DNA. Thus, it does not involve any looped regions. The lampbrush chromosomes do not occur in the males. However, exceptions include Drosophila Y chromosomes showing lampbrush loops. These regions involve active transcription process. The lampbrush chromosomes show a greater thickness as compared to the 30nm chromatin fiber. It is due to the high amount of ribonucleoprotein arising due to active transcription. The amphibian lampbrush chromosomes show the presence of telomeres. These regions look like granules. However, the telomeres of the bird lampbrush chromosomes consist of additional loops attached to the telomeric granules at one end. The other end carries a free telomeric sequence involving transcription from only the C- rich strand.