Zea Mays

See - McClintock, B. 1941. The stability of broken ends of chromosomes in Zea Mays. Genetics 26:234-282.

“If chromosomes are broken by various means, the broken ends appear to be adhesive and tend to fuse with one another 2-by-2. . . . As the two centromeres of the terminally united chromosomes pass to opposite poles in this mitotic anaphase, a chromatid bridge is produced. The tension on the bridge configuration, following the poleward migration of the centromeres, results in rupture. Once again, a chromatid with a broken end enters each sister telophase nucleus.”

“(1) If a chromosome, broken at the previous meiotic anaphase, is delivered to the primary endosperm nucleus through either the male or the female gametophyte, the breakage-fusion-bridge cycle will continue in the successive nuclear divisions during the development of the endosperm tissues. (2) A similarly broken chromosome delivered to the zygote nucleus by either sperm or the egg does not give rise to bridge configurations in successive nuclear divisions in the sporophytic tissues. (3) The breakage-fusion-bridge cycle is confined to the gametophytic and endosperm tissues of the generation immediately following the initial break in the chromosome. (4) Healing of the broken end in the embryonic sporophyte is permanent. When a chromosome with a healed broken end is introduced into gametophytic or endosperm tissues in succeeding generations, no fusion of broken ends result either between sister halves of the broken chromosome or between two such broken chromosomes when both are introduced into a single nucleus.” McClintock (Genetics 26:234-282).