Abstract
Electron micrographs of the relatively young spermatids of the Ascidian, Boltenia villosa, reveal that its chromosomes exist in the form of 120–180 Å fibers which are easily seen to be composed of two subunits of about 50–70 Å each. Fibers of the diameter of such subunits have never been seen as single entities without a mate. Subunits in pairs seen imbedded in areas of “fused” chromosomes only measure 30–40 Å, probably due to the loss of some protein. It is pointed out that the chromatin goes into the sperm as chromosomes in two-chromatid state, and that each chromatid probably contains only one Watson-Crick double helix.
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Hsu, W.S. Fine structure observations on the chromosomes in the spermatids of the Ascidian, Boltenia villosa . Chromosoma 24, 288–299 (1968). https://doi.org/10.1007/BF00336196
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DOI: https://doi.org/10.1007/BF00336196