In the order Kentrogonida, the virgin externa contains no openings at first. But it soon molts to a second stage that contains an orifice known as the mantle departure, and which leads into the two receptacle passageways — once assumed to be the testes in hermaphroditic parasites before the realization that they were actually two separate sexes — and starts releasing pheromones to attract male cyprids. From inside the body of the male cypris that succeeds in entering the departure, a unique and very short lived male stage called the trichogen emerges through the antennule opening. It is the homologue of the female kentrogon, but is reduced to an amoeboid, unsegmented and cuticle covered mass of cells consisting of three to four cell-types: the dorsolateral, the ventral epidermis, the inclusion cells, and the postganglion. The externa have room for two different males, one for each of the receptacles, which increase the heterozygosity of the offspring. Once inside, the trichogen will shed its cuticle before reaching the end of the passageway.