part of develops into developing embryonic structure extended germ band embryo dorsal closure embryo primordium salivary gland body primordium FBbt:00005621 Primordium that will form the secretory body of the embryonic/larval salivary gland. This primordium is first apparent as two epidermal placodes on the medial surface of the labial buds during stage 11. These placodes invaginate during embryonic stage 11 to form simple tubes on each side of the embryo that are positioned approximately along the dorso-ventral axis. Once internalized, the primordia migrate posteriorly during embryonic stage 12. They fuse to the developing salivary gland common duct by stage 13 and shortly after begin to show signs of secretory activity. embryonic salivary gland salivary gland body specific anlage FBbt:00005512 fly_anatomy.ontology P1 SalG presumptive embryonic salivary gland embryonic/larval salivary gland body ventral ectoderm derivative