ARBORESCENT ORGAN
1) a branched, accessory, vascular structure in the gill chamber, e.g. in Clarias gariepinnis
2) dendritic organ (a small arborescent organ found between the anus and the anal fin in certain Plotosidae (e.g. Plotosus, Cnidoglanis and Euristhmus). Organ with two main cell types, those with parallel groups of cytoplasmic tubules and many mitochondria, and clear cells with a network of cytoplasmic tubules. May have an osmoregulatory function)