Crossing-over and Recombination During Meiosis
Illustration of crossing-over and recombination during the formation of gametes
(germ cells) or meiosis. Crossing-over is part of a complicated process which
can occur during cell division.
In meiosis, the precursor cells of the sperm or ova must multiply and at
the same time reduce the number of chromosomes to one full set. During the
early stages of cell division in meiosis, two chromosomes of a homologous
pair may exchange segments in the manner shown above, producing genetic
variations in germ cells.
Morgan T.H., Sturtevant A.H., Muller H.J., and Bridges C.B., "The Mechansim
of Mendelian Heredity", 1915.