Leptotene (Gr. leptos = thin; taenia = band / stripe) is the first stage of meiosis. This is also the first step in the condensation of DNA, a phenomenon that proceeds through the entire prophase I. Despite the thread-like aspect of th chromosomes each consist in fact of twee chromatides, because the DNA has been already replicated during the premeiotic S-fase. Also small regions with thickenings (so-called chromomeres) arise in the chromatine on each chromosome, which make them look like a pearl nacklace. The homolog chromosomes are still unpaired.
