| Popis: |
The morphology of electroreceptive organs in lampreys and their larvae, different fishes, aquatic amphibians, and monotreme mammals is described. The sense organs vary from superficial end buds in lampreys, to ampullary organs and tuberous organs in many fishes and amphibians, to specialized mucous glands in the monotremes. The sensory cells are quite different. Some have a bundle of apical microvilli, as in lampreys and many teleost fishes. Cartilaginous and non-teleost fishes have a single apical cilium that in some species is surrounded by a few microvilli. Caecilian and urodele amphibians may have both a cilium and microvilli. Only the monotremes lack specialized sensory cells, possessing instead naked nerve endings connected to mucous glands. In all electroreceptive organs examined, only afferent nerve endings have been identified. |
