Hormones regulating structural changes in the adipocytes of the female earwig Labidura riparia

Abstract

Changes in periovarian fat body fine structure occur during the reproductive cycle of the female earwig Labidura riparia. During the process of vitellogenesis, high levels of protein synthesis are seen in the adipocytes. Simultaneously, the formerly osmiophilic lipid droplets become non-osmiophilic, while an osmiophilic material diffuses from lipid droplets to the cisternae of the rough endoplasmic reticulum (RER). These structural features alter during non-vitellogenic periods: RER and Golgi apparatus regress and seem to be inactive. Lipid droplets are once again osmiophilic and no material enters into RER cisternae. Using microsurgical manipulations, hormonal treatments and light and electron microscopy, we have investigated the regulation of these changes. The neuroendocrine cerebral centre pars intercerebralis, by the action of the juvenile hormone of the corpus allatum. triggers protein metabolism. Another neuroendocrine center, the pars lateralis. and the hormone 20-hydroxyecdysone, regulate structural lipid droplet changes in the adipocytes.