Structural changes in insect neuromuscular junctions in lanthanum solution

• 1.1. An electron microscopic study was made of the effect of lanthanum ions on the neuromuscular junction of the cockroach Periplaneta americana leg muscles. Experimental muscles were treated with 5mM La-saline for 2, 4 and 17hr at 4°C or 2 hr at room temperature (20–22°C).
• 2.2. After exposure to lanthanum for 2 hr at 4 C synaptic vesicles appeared to be slightly reduced in number, but the terminal mitochondria appeared unchanged. After the exposure for 4hr at 4°C the majority of the terminals were fairly depleted of vesicles. No synaptic contact was recognized at this time. By 17 hr all terminals were almost devoid of synaptic vesicles.
• 3.3. The effect of lanthanum ions on the structural changes was markedly affected by temperature, 2 hr of treatment with La-saline being enough to deplete the synaptic vesicles at room temperature.
• 4.4. From the results obtained and literature cited the ultrastructural changes may correlate with the functional changes in the insect neuromuscular junction.