Ultrastructure of Epitracheal Gland during Larval-Pupal Molt of Bombyx mori

Abstract

Ultrastrucutral changes of the epitracheal gland of Bomyx mori were observed electronmicroscopically during the molting cycle. One of the most notable characteristics is that the gland cell contains numerous electron dense droplets in the cytoplasm. These droplets are produced in the cytoplasm during the feeding period, and are degenerated during the molting stage. The degenerated fibrous materials are temporarily stored in variously sized vacuoles in the cytoplasm, and then these materials seem to be released into the hemolymph. From these observations, it is believed that the gland is a sort of endocrine organ functioning in periodic biosynthesis and in the release of the digested materials with each molting cycle.