Conjugation – Protozoan

Conjugation is characteristic of ciliates. The details vary from species to species. The general features can be observed in Paramecium sps. which has one macronucleus and one micronucleus. Two ciliates ready for conjugation partially unite. The body surface and pellicle undergo considerable changes. The macronucleus disintegrates and the micronucleus divides twice to give rise to four haploid pronuclei. Three of these disintegrate and the fourth forms a stationary and a migratory pronucleu.

Figure:  conjugation  in Paramecium caudatum

The latter moves into the other conjugant. The two organisms now separate and the pronuclei unite to form zygote. after several post conjugation divisions the macronucleus and micronucleus are formed restoring the normal nuclear complement.