Bivalents


Also found in: Dictionary, Thesaurus, Medical.
Related to Bivalents: bivalent chromosome

Bivalents

 

pairs of connected (conjugated) homologous chromosomes formed during nuclear division in meiosis. Chiasmas—X-shaped figures—are formed between chromosomes; they hold the chromosomes together within the complex. Genetic material may be exchanged at this time. The number of bivalents is normally equal to the number of chromosomes of the haploid (single) set.

References in periodicals archive ?
The overall average chromosome pairing behavior for both accessions was 0.24 univalents + 17.45 bivalents + 1.22 quadrivalents.
The overall average pairing for these two accessions was 0.28 univalents + 15.62 bivalents + 2.12 quadrivalents.
The high percentage of bivalents in this hybrid indicated the close relationship between F.
napus under observation revealed its true diploid nature, 2n= 38, 19 bivalents at metaphase-I of meiosis which confirm the previous result of U (1935), whole genome duplication facilitate high diversification Tank et al., (2015).
In diplotene/diakinesis some the autosomal bivalents shows telomeric associations (Fig.
The Spermatocytes.--Ditactic bivalents were first described in species of the genus Stethophyma by McClung (1928), who believed they resulted from cases in which chiasmata are only confined to the short arms of acrocentric chromosomes, an opinion which was held and reiterated by White (1951, 1973).
The meiotic analysis of Aster squamatus showed 10 chromosomes in bivalent associations (II) in diakinesis and metaphase 1 (Figure 1a), normal chromosomal segregation in anaphase 1 (Figure1b) and telophase 1, and retarding chromosomes in telophase II (Figure 1c), as well as cells with 3 poles (Table 1), and one cell with 5 (Figure 1d).
leucopus) of the four examined in Baker and Wichman (1990), reveal a distinct interstitial chiasma in the heterochromatic region delimited by the centromeres and pseudoautosomal telomeres of the XY bivalent. Because genetic and molecular markers are not available for the pseudoautosomal region of the deer mouse, the possibility that X-Y recombination is limited to a very small segment within this region cannot be summarily excluded.
Meiosis is achiasmatic; all bivalents are homomorphic, condensing gradually until metaphase I (Fig.
In the soybean hypertriploid, the second type of chromosome configuration was observed in a majority of the PMCs (63%), suggesting that the four homologous chromosomes primarily formed two bivalents. In the barley hypertriploids, the frequency of the first type was marginally higher than that of the second and third types.