Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Development of a penis from the vestigial penis in the female apple snail, Pomacea canaliculata.

Abstract

In the apple snail (Pomacea canaliculata), females have an undifferentiated mass of tissue near the anus. Although this mass is called the vestigial penis, there are no signs of a hermaphroditic gonad or any structure that represents a transition from one sex to the other. Based on considerations of the steroid hormone theory of reproduction and in view of disruption of endocrine systems in molluscs by organotins, a study was made of the effects of tributyltin on female snails. Exposure to tributyltin resulted in the so-called imposex phenomenon, and both a penis and a penis sheath were newly generated from the so-called vestigial penis. The same phenomenon was also induced by testosterone. Thus the vestigial penis, named more than one hundred years ago, has been demonstrated for the first time to be a rudiment of the penis itself.