Gonophore

A gonophore is a reproductive organ in members of the Hydrozoa which produces gametes. It is a sporosac, a medusa or any intermediate stage. The name is derived from the Greek words γόνος (gónos, "that which produces seed") and -φόρος (-fóros, "-bearing").

Gonophores are borne on branching stalks that grow radially outward from the wall of a hydranth (i.e. the hydroid polyp, bearing a mouth, digestive cavity and tentacles). The germ cells are formed from the inner layer of the entocodon, which is the primordium (i.e. the first cells that give rise to the development of an organ) of the subumbrella (i.e. the concave oral surface of a medusa) in the development of medusae from the gonophore.^[1]