[Siphonophora] Medusa stage bearing sexual products.

[Hydromedusae] In many Hydroidomedusae the medusa stage is reduced to a varying degree and is no longer liberated, remaining attached to the hydroid, in these cases it is called a gonophore or sporosac or, since it is not released, a fixed sporosac.

Alternative form for Gonophore : Gonophores (pl.).