The structure of the terminal sensilla on the maxillary palps of Locusta migratoria (L.), and changes associated with moulting

Summary The basic structure of the terminal sensilla of Locusta migratoria resembles that of Schistocerca gregaria. There are commonly six or ten neurons whose dendrites extend almost to the opening of the peg. Proximally the dendrites are clothed by a neurilemma cell which also encloses a basal cavity through which their ciliary region passes. The tormogen cell encloses the receptor-lymph cavity and actively secretes material into it. The receptor-lymph cavity and the basal cavity are quite separate.The development of new pegs at a moult is described. After apolysis the scolopale extends across the subcuticular space and protects the dendrites, which remain in a functional condition until shortly before ecdysis. As the trichogen cell grows out to form a new peg the tip is surrounded by a mass of electron-dense material, probably derived from the receptorlymph cavity. The function of this material is unknown. Regeneration of the dendrites is considered.The possible mechanism by which the tip of the peg opens and closes is considered and the general structure of the organule is discussed in relation to functioning.