Sporangiophores are unbranched aerial hyphae of Rhizopus, which appear during asexual reproduction. The tip of each sporangiophore develops a swollen sac called sporangium. Internally sporangium is separated from the rest of the sporangiophore by a dome-shaped partition called columella. A sporangium produces hundreds of non motile haploid spores called sporangiospores, which are dispersed by air currents. Zygophores are subaerial hyphae that take part in sexual reproduction and result in the formation of a diploid zygote, which gets transformed into a resting spore called zygospore. Zoospores are not formed in Rhizopus.