Fig. 5

Co-expression of examined genes suggests i-cell function during gonophore formation and transient expression in the germ line, exemplary presentation of vasa-1 transcript localization. a Mature cormidium, including male and female gonodendra. Anterior is to the left, ventral to the top. b–e Ontogenetic series of developing female gonodendra. b Cell cluster with vasa-1 expression at the site of gonodendron formation at the base of a palpon. c Developing bean-shaped female gonodendron. d Developing female gonodendron starting to spiral. e Mature female gonodendron with developing gonophores with vasa-1 expression and mature gonophores with vasa-1 expression absent. f Close-up of female gonodendra (boxed area in e) with developing (black arrowhead) and mature gonophores (white arrowhead). Distal is up. g Close-up of the base of a male gonodendron. Later gonophores bud off the peduncle of the primary gonophore. The primary male gonophore (mgo1) is visible to the right. h Male gonodendron with an ontogenetic series of male gonophores, labeled mgo1-4 from oldest to youngest. vasa-1 signal intensity decreases as the male gonophore matures. fg female gonodendron, fgo female gonophore, g gastrozooid, goc gonodendron cell cluster, mgo male gonophore, mgo1 oldest male gonophore, p palpon, ped peduncle, sst siphosomal stem