STRUCTURE AND FUNCTION OF THE AXILLARY ORGAN OF THE GULF TOADFISH, OPSANUS-BETA (GOODE AND BEAN)

The structure of the axillary organ of a batrachoidid species, the gul f toadfish (Opsanus beta Goode and Bean 1879), has been examined and s everal simple experiments designed to elucidate its function performed . Electron microscopy (EM) studies revealed cells and structures sugge sting secretory and iono regulatory roles (e.g., abundant intracytopla smic secretory particles, rough endoplasmic reticulum, sparse Golgi bo dies, indented epithelial cells with microvilli, numerous endocytotic vesicles, etc.). Our physiological experiments allowed us to reach sev eral conclusions: the organs do not excrete significant quantities of urea relative to other areas of the fish (head and gills), the organs do not secrets a substance that is toxic to a teleost test fish (Gambu sia affinis), the secretions do not induce short-term modifications in locomotory activity of other gull toadfish (e.g., by pheromonal means ) and the secretions do not inhibit the growth of several species of m icroorganisms in culture, The function of the organ and its secretions remains unknown, representing a fertile area for research on structur e and function in comparative physiology. COMP BIOCHEM PHYSIOL 119A;1: 17-26, 1998. (C) 1998 Elsevier Science Inc.