Description:
Abstract The ontogenesis of the organs of the lateral-line system of the alpine newt (Triturus alpestris) was examined with special emphasis on the ampullary organs using resin embedded thick sections. The mechanoreceptive neuromasts and the electroreceptive ampullary organ were indistinguishable prior to hatching. At hatching only few ampullary organs were found around the eye. These organs consist of one or two egg-shaped sensory cells and a few supporting cells. The ratio of ampullary organs and neuromasts changes from 1:15.6 (stage 36) to 1:1.1 (stage 62). The number of unidentifiable organs decreases constantly over this period of time and becomes zero at the oldest stages observed. Besides an absolute numerical increase in both types of organs both grow by increasing the number of cells per organ. Comparison with the development of the ampullary organs in catfish shows a striking similarity which suggest either similar functional constraints acting on both catfish and newts or can be interpreted as an indication of homology of both types of organs.