prophase /pro·phase/ (-fāz) the first stage in cell reduplication in either meiosis or mitosis.
prophase
pro·phase (pr  f z )n. 1. The first stage of mitosis, during which the chromosomes condense and become visible, the nuclear membrane breaks down, and the spindle apparatus forms at opposite poles of the cell. 2. The first stage of meiosis, during which the DNA replicates, homologous chromosomes undergo synapsis, chiasmata form, and the chromosomes contract. pro·pha sic (-fz k) adj. |
prophase
[prō′fāz]
Etymology: Gk, pro + phasis, appearance
the first of four stages of nuclear division in mitosis and in each of the two divisions of meiosis. In mitosis the chromosomes progressively shorten and thicken to form individually recognizable elongated double structures composed of two chromatids held together by a centromere. The nucleolus and nuclear membrane disappear, the spindle and polar bodies are formed, and the chromosomes begin to migrate toward the midplane of the developing spindle. In the first meiotic division, prophase is complex and subdivided into five stages: leptotene, zygotene, pachytene, diplotene, and diakinesis. In the second meiotic division the same processes occur as in mitotic prophase. See also anaphase, interphase, meiosis, metaphase, mitosis, telophase.
prophase
the first stage of cell replication in either meiosis or mitosis.
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