Local metamorphic action of thyroxine analogues inRana pipiens larvae,

✍ Scribed by Kaltenbach, Jane Couffer

• Book ID: 102892206
• Publisher: John Wiley and Sons
• Year: 1970
• Tongue: English
• Weight: 713 KB
• Volume: 174
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1401740106

✦ Synopsis

Abstract

To determine whether or not various thyroxine analogues accelerate metamorphosis by acting directly upon target organs, analogue‐cholesterol pellets were prepared and implanted into the dorsal tail fins of Rana pipiens larvae. Many analogue implants caused localized fin resorption, a response attributed to the direct action of the analogue upon the fin. Analogues with acetic or propionic acid side chains or with an isopropyl group but no iodine atoms in the β ring were effective in lower concentrations than was thyroxine; on this basis, the most active compounds were triiodothyropropionic acid and isopropyldiiodothyronine. Fin resorption was not induced by implants of diiodophenoxyacetic acids or of dihalogenated methoxythyranilines. Yet, intraorbital implants of these compounds did stimulate glandular development in the skin dorsal to the eye (a region with a lower threshold of response to thyroxine than the tail fin). The causation of local metamorphic responses, either in the tail fin or in the orbital region, by various thyroxine analogues indicates the direct action of such compounds upon peripheral tissues of the tadpole.