Conjugation begins when individuals of opposite mating types meet, the adhere to
each other at the oral groove. The micronuclei then divide meiotically,
producing four haploid nuclei each. All but one nucleus from each paramecium
disintegrate. The macronucleus also disintegrates, leaving each cell with one
haploid micronucleus. These remaining nuclei then divide mitotically and the two
cells swap copies of their nuclei. The cells separate and the haploid nuclei
fuse, leaving each cell with a new diploid micronucleus. To form a new
macronucleus, the micronucleus divides several times and the resulting nuclei
develop into a macronucleus.