Local decondensation of chromatic at the surface of meiotic chromosomes during anaphase movement.

Chromosomes in male meiosis of the crane fly Pales ferruginea develop characteristic lamellar chromatin projections (LCPs) at their periphery during anaphase movement. LCPs have a thickness of about 30 nm on the average and are 0.1 to 0.35 microns wide. They run alongside the chromatids in the direction of the spindle axis, and are associated with rows of spindle microtubules. Analysis of serial sections through different planes showed the chromatin of the LCPs to be relatively decondensed revealing stretches of chromatin fibers about 30 nm in diameter. It is assumed that the LCPs result from local uncoiling or unfolding of the condensed metaphase chromatid, and are formed by interaction with spindle microtubules. The development of LCPs would be compatible with a "Radial Loop Model" of the metaphase chromatid as proposed by others.