- the first stage of mitosis or meiosis in eukaryotic cell division, during which the nuclear envelope breaks down and strands of chromatin form into chromosomes.
- the first stage of mitosis, during which the nuclear membrane disappears and the nuclear material resolves itself into chromosomes
- the first stage of meiosis, divided into leptotene, zygotene, pachytene, diplotene, and diakinesis phases
