Confocal microscopy of the lizard motor nerve terminals

Confocal imaging was performed on the ceratomandibularis nerve muscle preparation of the lizard Anolis carolinensis, using 4-Di-2-ASP as a fluorescent probe. The imaging system consisted of a Sarastro Phoibos 1000 (Molecular Dynamics) scanning system and a Zeiss Universal microscope. The data were analyzed using the VANIS set of programs on a Silicon Graphics Personal Iris computer. A three dimensional reconstruction of the nerve terminals was performed using look-through and depth-coded projections. The volume of the nerve terminal was estimated in 15 neuromuscular junctions and found to be 84,835 microns 3 (+/- 8558 SEM). The largest diameter in each one of the 178 individual boutons was estimated from the look-through projections of 17 nerve terminals in 9 preparations. It was found to be 4.71 microns (+/- 0.08 SEM). The diameter perpendicular to the largest diameter in the same projection at 0 degrees was 3.3 microns (+/- 0.054 SEM). Thus it seems that the synaptic boutons of the ceratomandibularis are suitable for combined optical and electrophysiological recordings.