n. the second stage of *mitosis and of each division of *meiosis, in which the chromosomes line up at the centre of the *spindle, with their centromeres attached to the spindle fibres.
n. one of the two threadlike strands formed by longitudinal division of a chromosome during *mitosis and *meiosis. They remain attached at the *centromere. Chromatids can be seen between early prophase and metaphase in mitosis and between diplotene and the second metaphase of meiosis, after which they divide at the centromere to form daughter chromosomes.... chromatid
(fluorescence in situ hybridization) a technique that allows the nuclear DNA of *interphase cells or the DNA of *metaphase chromosomes, which are fixed to a glass microscope slide, to anneal with a fluorescent gene *probe. It is used for detecting and locating gene mutations and chromosome abnormalities.... fish
(reduction division) n. a type of cell division that produces four daughter cells, each having half the number of chromosomes of the original cell. It occurs before the formation of sperm and ova and the normal (*diploid) number of chromosomes is restored after fertilization. Meiosis also produces genetic variation in the daughter cells, brought about by the process of *crossing over. Meiosis consists of two successive divisions, each divided into four stages (see prophase; metaphase; anaphase; telophase). (See illustration.) Compare mitosis. —meiotic adj.... meiosis
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