An anomalous sensillum chaeticum with a double set of cilia and outer dendritic segments in Bombyx mori L. (Lepidoptera : Bombycidae)

Abstract

An anomalous sensillum chaeticum is described in the silkmoth, Bombyx mori (Lepidoptera : Bombycidae), in which each of the 5 inner sensory dendrites gives rise to 2 ciliary and 2 outer dendritic segments. This is interpreted as an atavistic feature, because a double set of cilia is common in sensilla of apterygote insects and of non-insect arthropods. Since all the sensory cells of the sensillum were affected in the same way, determination of the number of cilia and outer segments must have occurred early in morphogenesis, i.e. before the differential cell divisions of the sensory mother cell.