title: Studies on the venomous spicules and spines of moth caterpillars. I. Fine structure and development of the venomous spicules of the Euproctis caterpillars.
abstract: Scanning and transmission electron microscopy (SEM and TEM) revealed unique structures and development of the venomous spicules of tussock moth caterpillars of the genus Euproctis: (1) Flower-like structure at the distal end and a longitudinal minute depression on the proximal subapical wall of these spicules were observed by SEM. This depression was revealed to be a small hole by TEM. (2) During molting, observed were cytoplasmic processes of several trichogen cells penetrating the cytoplasm of a tormogen cell to form the spicules with the holes at their subapical portions. A papilla was formed by a tormogen and several epidermal cells. (3) After the molting, the cytoplasmic process in a spicule disappeared and the spicule cavity was replaced by electron-dense materials secreted apparently from the trichogen cell. (4) It was considered that the electron-dense materials were the main toxic or precursory substances in the Euproctis spicules.
mesh_terms: D000818:Animals; D001180:Arthropod Venoms; D007814:Larva / Q000033:anatomy & histology; D007915:Lepidoptera / Q000033:anatomy & histology*; D008854:Microscopy, Electron; D009036:Moths / Q000033:anatomy & histology*
chemical_list: D001180:Arthropod Venoms