ABSTRACT
Examination of the neuromasts in the tail of the living juvenile axolotl Ambystoma mexicanum with interference contrast (Nomarski) microscopy shows that their cellular structures can be identified in considerable detail. Microscopy was performed with a 40 x water immersion objective or with a 100 x objective in a tail insertion chamber. Thus the sensory hair bundles can be seen and their orientation can be determined. Large spheres in the basal part of the sensory cells were predicted to be synaptic bodies. Subsequent examination in the transmission electron microscope of the cells observed in the light microscope confirmed this notion. Inspection during periods of several hours reveals definite movements of the synaptic bodies.
Subject(s)
Ambystoma mexicanum/physiology , Neurons, Afferent/physiology , Synaptic Transmission/physiology , Tail/anatomy & histology , Animals , Larva , Microscopy, Electron , Microscopy, Phase-Contrast , Neuronal Plasticity , Neurons, Afferent/cytology , Neurons, Afferent/ultrastructureABSTRACT
New lateral organs (neuromasts) are formed in regenerating tails of the larvae of a urodele, the axolotl (Ambystoma mexicanum), even in the absence of the lateral line nerve, as confirmed by electron microscopic examination. The non-innervated organs are similar to normal innervated organs. The hair cells are polarized in opposite directions, and despite the lack of nerve endings, contain synaptic bodies, which in normal innervated organs are found in relation to afferent boutons.