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the structure formed by a pair of homologous chromosomes joined by synapsis along their length during the zygotene and pachytene stages of the first meiotic prophase. After each homologous chromosome splits into two sister chromatids during the pachytene stage, this structure is called a tetrad.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
2. In cytology, a structure consisting of two paired homologous chromosomes, each split into two sister chromatids, as seen during the pachytene stage of prophase in meiosis.
See also: tetrad.
See also: tetrad.
Farlex Partner Medical Dictionary © Farlex 2012
1. Genetics Relating to or being a pair of homologous, side-by-side chromosomes, especially during meiosis; double.
2. Chemistry & Immunology Divalent.
bi·va′lence, bi·va′len·cy n.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
adjective Referring to an atom with 2 valent states.
adjective Referring to either of 2 homologous chromosomes in synapsis during meiosis.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.
1. Having a combining power (valence) of two.
2. cytology a structure consisting of two paired homologous chromosomes, each split into two sister chromatids, as seen during the pachytene stage of prophase in meiosis.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
bivalent(of a pair of homologous CHROMOSOMES) being paired during prophase I of MEIOSIS. Compare MULTIVALENT.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005