Histological Observation of Eggs of the Embryonic Lethal Mutation Set in Bombyx mori

Abstract

A mutation named Set, which has been characterized by abnormal larval traits, shows embryonic lethality as a pleiotropic effect. Light microscopic observations of the dying eggs without hatching of this mutation indicated that the epithelial cells of the midgut, especially the microvilli, were abnormal. Other tissues and organs of Set embryos were confirmed to develop fully, but massive yolk remained in the lumen of the midgut, indicating that yolk proteins were not utilized. We infer that the Set mutation brings about functional impairment of the midgut digestive/absorption system.