What are lampbrush chromosomes?

Answer: Except mammals, most animals’ developing oocytes (immature eggs) contain lampbrush chromosomes, a unique type of chromosome. Walther Fleming and Ruckert initially described them in 1882. The best descriptions of lampbrush chromosomes come from tail and wingless amphibian, insects and birds.  Due to the active translation of numerous genes, chromosomes change into the lampbrush phase even during diplotene phase of meiosis 1 I. They are mitotic cell half-bivalents that are greatly elongated and made up of two sister chromatids each. Even under a light microscope, lampbrush chromosomes are plainly visible and can be observed to be arranged as a sequence of chromosomes with huge chromatin loops that are stretched horizontally.