When the free ends of the hyphae emerge again into the air they swell up into spherical bodies which may either fall off and behave as conidia, each putting out a germ-tube and infecting the host; or the germ-tube itself swells up into a zoosporangium which develops a number of zoospores.
Each "conidium" contains numerous nuclei and is really a zoosporangium, as after dispersal it breaks up into a number of zoospores.
To a zoosporangium, but may form directly a germ tube which infects the host.
Motile zoospores which escape from the zoosporangium are present except in Aplanes.
In unicellular forms (Sphaerella) the thallus becomes transformed into a zoosporangium at the reproductive stage.