The virgin bursa copulatrix of the butterfly, Calpodes

The different parts of the bursa copulatrix of virgin females of Calpodes ethlius have fine structures consistent with their different functions. The thin pitted cuticle of the bursal sac and its underlying epithelium suggest an absorptive function, with their 'pores' and numerous mitochondria respectively. The highly folded junctional region with its robust muscle and epithelium anchored to the thick folded spinous cuticle by sockets and their tonofibrillae suggest a holding structure capable of great muscular activity. The bursal duct with its hardened cuticle might serve to hold the body of the elongated, cone-shaped sperm sac straight and in position so that its contents might be more easily squeezed out into the seminal duct, whose opening is adjacent to the open end of the sperm sac.