. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 1MPOSEX IN THE APPLE SNAIL. P. CANALICULATA 319. Figure 4. (A) A penis that arose from the vestigial penis of a female apple snail (Pomacca canaliculate!) after treatment with tributyltin for about 7 months. The same phenomenon was also seen in female snails reared with testosterone for about 8 months. See legend to Fig. 3A for methods. (B) The extirpated penis from the vestigial penis. See legends to Fig. 2 and 3 for other abbreviations. Scale represents 1 mm. The "steroid hormone theory," which I proposed previou
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 1MPOSEX IN THE APPLE SNAIL. P. CANALICULATA 319. Figure 4. (A) A penis that arose from the vestigial penis of a female apple snail (Pomacca canaliculate!) after treatment with tributyltin for about 7 months. The same phenomenon was also seen in female snails reared with testosterone for about 8 months. See legend to Fig. 3A for methods. (B) The extirpated penis from the vestigial penis. See legends to Fig. 2 and 3 for other abbreviations. Scale represents 1 mm. The "steroid hormone theory," which I proposed previously (28, 29) for the reproduction of terrestrial pulmonates, appar- ently also applies to prosobranch snails. This theory states basically that the development of accessory sex organs is controlled by steroid hormones secreted by the gonad. This concept of the effects of hormones on snail reproduction, together with the effects of endocrine disruption in molluscs, allowed me to demonstrate, for the first time, that the so-called "vestigial penis," named more than one hundred years ago (4. 5), is a rudiment of the penis itself. Literature Cited 1. Perera, G., and J. G. Walls. 1996. Apple Snails in the Ai/uarium, T. F. H. Publications, Jersey City. NJ. 121 pp. 2. Fioroni, P., J. Oehlmann, and E. Stroben. 1991. The pseudoher- maphroditism of prosobranchs: morphological aspects. Zool. An:, 226: 1-26. 3. Takeda, N. 2000. Mollusca. Pp. 43-147 in Reproductive Biology of Invertebrates, Vol. 10, Part A. Progress in Developmental Endocri- nology, A. Dorn, ed. John Wiley. New York. 4. Bouvier, E. L. 1888. Sur I'anatomie de 1'Ampullaire. Bull. Soc. Plnlom. Paris 12: 5-70. 5. Bouvier, E. L. 1888. Etude sur 1'organisation des Ampullaires. Mem. Soc. Philom. Paris (centenary vol.) 63-85. 6. Sachwatkin, V. A. 1920. Das Urogemtalsystem von Ampul/aria gigans Spix. Acta Zool. (Stock/i.) 1: 67-130. 7. Hagler, K. 1923. Anatomic von Pachylabra (Ampul/aria) cinerea (Reeve). 1. Teil. Mit Eins
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