pachytenen.
/ˈpakᵻtiːn/, U.S. /ˈpækəˌtin/ Cell Biology.
In cell division: the third stage of the first meiotic prophase, following zygotene, during which the paired chromosomes shorten and thicken, the two chromatids of each may separate, and exchange of segments between chromatids may occur. Frequently attributive.
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the world > life > biology > biological processes > genetic activity > [noun] > stages of mitosis or meiosis
resting stage1810
prophase1884
anaphase1887
metaphase1887
synapsis1895
telophase1895
maturation division1896
postsynapsis1898
strepsinema1900
synizesis1905
interkinesis1906
pachynema1909
telosynapsis1909
leptonema1911
metasyndesis1911
strepsitene1911
zygonema1911
zygotene1911
leptotene1912
pachytene1912
interphase1913
telosyndesis1920
prometaphase1931
dictyotene1957
dictyate1958
1900 Jrnl. Royal Microsc. Soc. 654 As the chromatic thread spreads itself again through the nuclear space, this duality disappears, and the thread is single, thick, and moniliform (pachytænic stage).]
1912 Jrnl. Exper. Zool. 13 378 All the threads still stain deeply and are very much thicker than in the leptotene-stage; hence these nuclei may be called the pachytene-nuclei.
1932 Proc. 6th Internat. Congr. Genetics 1 257 It is assumed that every chiasma represents a crossover which has occurred between two of the four chromatids at pachytene.
1965 P. Bell & D. Coombe tr. Strasburger's Textbk. Bot. (new ed.) 34 In pachytene the pairing of homologous chromosomes is completed.
1989 B. Alberts et al. Molecular Biol. Cell (ed. 2) xv. 848 Pachytene is said to begin as soon as synapsis is complete, and it generally persists for days, until desynapsis begins the diplotene stage, in which the chiasmata are first seen.
This entry has been updated (OED Third Edition, March 2005; most recently modified version published online March 2022).
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n.1912