external sensory organ precursor cell IIIb external sensory organ precursor cell pNb 2019-12-12T11:27:04Z FBbt:00048522 Third-order precursor cell that develops from an external sensory organ precursor cell IIb. In the development of antennal olfactory sensilla, it produces two daughters, Nba and Nbb, which will each either form a neuron or undergo apoptosis (Endo et al., 2012; Chai et al., 2019). fly_anatomy.ontology This cell and its daughters in the developing antenna can be distinguished by strong expression of Sens and lack of expression of Ham (Chai et al., 2019).