393HISTOLOGICAL STUDIES ON SEX PHEROMONE SOURCE IN FEMALE AMERICAN COCKROACH, PERIPLANETA AMERICANAInsects perceive the world through small molecules which carry information called as “Pheromones”. Sex pheromone, in most insects is usually released by females to attract males. In American cockroach, Periplaneta americana, sex pheromone is produced in an adult female-specific cuticular abdominal gland located on the anterior of the last abdominal tergite. The basic structure of the cuticular abdominal gland was observed under the light microscope and the ultra-structural details were analysed with the help of Transmission and Scanning electron microscopic studies. The light microscopic analysis revealed that the anterior region of (i.e. tergal gland) American cockroach, observed to contain monolayer of epithelium, secretory vesicles and supportive cells. The secretory canal noted to contain a few secretory substances. The histochemical studies authentically proved that the secretory substance was protein in nature. Electron microscopic studies of cuticular abdominal gland revealed that the larger cells were noticed in the ventral part. The size of the nucleus was observed to be large round in shape. The nucleus is usually located in the basal region. The cells had a characteristic layer of microvilli just beneath the endo-cuticle. The endo-cuticle and the epi-cuticle had lamellae. The epi-cuticle was seemed to be denser than that of the endo-cuticle. During photo phase, the cells of cuticular abdominal gland became highly vesiculated with smaller vesicles that accumulated just below the microvilli. During scotophase, (i.e., dark phase) pockets of granular material were appeared throughout the cytoplasm of each cell and also noted within the microvilli. Finally, the cuticular hairs were examined, which revealed that the extensions of the epicuticle had a hollow core and many pore canals karunjunai@yahoo.co.inResearch4122013Periplaneta americana,Cuticular abdominal gland,Sex pheromone,Epi and endo cuticleArunjunai Rajan K,Kannan S,Baskaran SDepartment of Zoology, Government Arts College, Melur, Madurai, Tamil Nadu, India.,Department of Zoology, Ayya Nadar Janaki Ammal College, Sivakasi-626 124, Tamil Nadu, India., Department of Zoology, Periyar University, Salem-636011, Tamil Nadu, India.