part of develops into protocerebral bridge primordium larval posterior inferior protocerebrum synaptic neuropil domain embryonic/larval protocerebral bridge - primordial 2015-09-15T16:59:51Z FBbt:00111206 fly_anatomy.ontology larvalbrain_neuropil:581 larvalbrain_neuropil:403 embryonic/larval protocerebral bridge larval PB primordium of protocerebral bridge prPB VFB:FBbt_00111206 The primordium of the adult protocerebral bridge in the larval brain, formed from the DPMm1 and DPMpm1/2 and CM4 lineages. Unlike in the adult, this exists as a bilateral pair of separate domains that do not join across the midline. These domains are tubular shaped regions containing both differentiated and undifferentiated synapses, in the posterior inferior protocerebrum (IPp or CPM). Each domain curls around the dorsal side from the posterior, growing during the larval period towards the midline. Fusion of the two halves, just posterior to the PLPC (DPLp1) commissure and fan-shaped body, only occurs 48h after pupariation. embryonic/larval PB