Lampbrush chromosomes. Coloured transmission electron micrograph (TEM) of lampbrush chromosomes (LBCs). A chromosome consists of proteins and DNA (deoxyribonucleic acid). DNA contains sections (genes) that encode the cell's structure and function. LBCs are found inside amphibian and bird oocytes (immature egg cells). They are known as giant (polytene) chromosomes, as they undergo repeated replications of DNA without nuclear divisions, creating elongated strands. These strands consist of a main axis, around which there are many brush-like loops. These loops allows the genes to be easily transcribed (processed) while the oocyte develops into a mature ovum (egg). LBC's are ideal models for exploring how chromosomes function due to their large size and open structure.