Meiotic arrest at diplotene stage commonly occurs in mammalian occytes. In females, meiosis starts in the embryo and proceeds as for as diplotene, when the chromosomes become diffused and the cells are referred to as being in the dictuate stage. This arrest is under hormonal control. In many amphibian oocytes binds and insects with a long period of immaturity, the oocyte may be arrested in the dictyate stage for many years and spend a prolonged period in diplotene. This stage is characterized by formation of lamp brush chromosomes where intense RNA synthesis occurs and most of the genes in the DNA loops are actively transcribed and expressed.