chiasma

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chiasma

(kīăz`mə): see crossing overcrossing over,
process in genetics by which the two chromosomes of a homologous pair exchange equal segments with each other. Crossing over occurs in the first division of meiosis. At that stage each chromosome has replicated into two strands called sister chromatids.
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chiasma

[kī′az·mə]
(anatomy)
A cross-shaped point of intersection of two parts, especially of the optic nerves.
(cell and molecular biology)
The point of junction and fusion between paired chromatids or chromosomes, first seen during diplotene of meiosis.
References in periodicals archive ?
Complex chiasms appear in many different structural shapes in the Bible, and one of the most basic forms is the chiastic inclusion, or ABA.
Oftentimes the springboard and rejoinder are absent, while at other times they are incorporated into the overall structure of the complex chiasms they border.
The final portion of this speech also happens to be another chiasm, which balances the opening chiasms in lines 175-76:
Next, by expanding each chiastic level with phrases composed of chiasms and periodic sentences (the outline of this passage generally follows the periodic sentences it contains), the full speech subsequently takes shape into a highly complex and interrelated passage:
13) Shakespeare incorporates periodic sentences of various lengths into his complex chiasms to assist in the narrative flow.
The introductory portion, termed anacrusis among biblical scholars (Watson 150), appears as a single word, a phrase, a parallelism, or a small paragraph that propels the text into the chiasm that follows.
In the following example, he not only uses parallelisms but sets two parallelisms (one in each A level) into corresponding positions in the passage, creating a structural chiasm (in this case, a chiastic inclusion, or ABA) for the main body of the speech:
In the following example from The Winter's Tale, Shakespeare creates a complex, overlapping chiasm that begins with a basic arrangement of related parallelisms, which he uses to bookend a second chiasm that lives in the center of the overall passage.