The biochemical and physical duet of the mother and the fetus in the formation of the placenta is one of the most carefully orchestrated phenomena in fetal development. It represents the cooperation of two distinct individuals to form a single structure that protects one and enables the genes of the other to live on.
This cycle is known as alternation of generations. The spores of seed plants, however, are produced internally and the megaspores, formed within the ovules and the microspores are involved in the formation of more complex structures that form the dispersal units, the seeds and pollen grains.
Microconidia are one or two celled, are produced by Fusarium oxysporum under all conditions, and produced the most within the infected plants. Macroconidia are three to five celled and are commonly found on the surface of plants that have been killed by Fusarium wilt. Chlamydospores are the third type of spore and are either one or two celled.