external sensory organ precursor cell IIIb external sensory organ precursor cell pNa 2019-12-11T16:18:52Z fly_anatomy.ontology This cell and its daughters in the developing antenna can be distinguished by expression of Ham (Chai et al., 2019). FBbt:00048521 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, Naa and Nab, which will each either form a neuron or undergo apoptosis (Endo et al., 2012; Chai et al., 2019).