. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. IMPOSEX IN THE APPLE SNAIL. P. CANALICULATA .7 317. Figure 1. General appearance of the vestigia] penis in a female apple snail (Pomacea canaliculata). The shell was removed and the region to the left of the head was dissected to reveal the vestigial penis (1), rectum (2), and oviduct (3), which are enclosed in a square. The siphon (4). pulmonary sac (5), albumen gland (6), and ovary (7) are also indicated. Scale bar represents 1 cm. As an approach to this problem, I examined the effects of an endocrine disruptor that appear
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. IMPOSEX IN THE APPLE SNAIL. P. CANALICULATA .7 317. Figure 1. General appearance of the vestigia] penis in a female apple snail (Pomacea canaliculata). The shell was removed and the region to the left of the head was dissected to reveal the vestigial penis (1), rectum (2), and oviduct (3), which are enclosed in a square. The siphon (4). pulmonary sac (5), albumen gland (6), and ovary (7) are also indicated. Scale bar represents 1 cm. As an approach to this problem, I examined the effects of an endocrine disruptor that appears to be associated with as yet unresolved environmental problems. Organotins, and in particular tributyltin, which is a component of some anti- fouling paints, induce a condition known as "imposex" in prosobranch gastropods. Imposex, in which a penis and vas deferens develop in females (21), has been widely observed in marine snails that belong to the Caenogastropoda; Nu- cella and Littorina are common examples (22). Females of these species lack a vestigial penis, but the capacity exists for induction of a penis and vas deferens. Pomacea canal- iculata has been proposed as a potential bioindicator for tributyltin (22), which is used as a biocidal agent against molluscs, in fungicides (23) and in anti-fouling paints in freshwater environments. Anticipating possible endocrine disruption by tributyltin, I examined its effects to see whether the vestigial penis in this species might develop further after female snails were exposed to this compound and, if such a penis did develop, how would it differentiate? Female specimens off. canaliculata were reared in water that contained 30 ng/1 tributyltin. About 3 months after the start of treatment, the outside of the elevated tissue of the vestigial penis began to form a long process that resembled a penis, and its interior developed as a thick mass. These structures grew gradually and reached a maximum size after about 6 mont
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
