Ultrastructure and maturation of a sex pheromone gland in the female German cockroach, Blattella germanica

Abstract

A volatile sex pheromone is produced in an adult female-specific gland located on the anterior of the last abdominal tergite of the female German cockroach, Blattella germanica (L.). In this area, the cuticle forms deep depressions in which a large number of cuticular orifices are located. The cuticular orifices are connected to secretory cells via cuticular ducts surrounded by duct cells. The pheromone gland exhibits a clear developmental maturation in relation to sexual maturation of the female. The secretory cells of a newly formed gland in the imaginal female are small and contain few secretory vesicles. The amount of extractable pheromone in the gland is low on day-0 but it increases with age and peaks on day-6. The secretory cells in a mature day-6 gland are characterized by a large number of electron-lucid secretory vesicles. abundant RER and SER, a large nucleus and a long, convoluted end apparatus which is lined with numerous microvilli. The contents of the secretory vesicles are exocytosed into extracellular reservoirs at the base of microvilli and then transported to the cuticular surface through the long ducts. The supportive function of the duct cell in the glandular organization and developmental regulation of the gland are discussed.