The megalospheric form reproduces sexually by syngamy or conjugation. A sperm stimulates the egg to develop without fertilisation or syngamy. Eukaryotic pathogens are often capable of sexual interaction by a process involving meiosis and syngamy. The microspheric forms are developed by the conjugation or syngamy. The pronuclear envelopes disappear and the parental chromosomes come together in a process called syngamy. The gametes which gives rise to microspheric form by syngamy. With multi-seeded fruits, multiple grains of pollen are necessary for syngamy with each ovule. Cell fusion (plasmogamy or syngamy) is a stage in the "Amoebozoa" sexual cycle. This combination of the two genomes is called syngamy. Syngamy can only take place between gametes carrying different mating types.