a and i bands in a sentence

1. A transverse tubule surrounded by two SR cisterna are known as triads, and the contact between these structures is located at the junction of the A and I bands.
2. In skeletal muscle cells, T-tubules are typically located at the junction overlap between the A and I bands of the sarcomere, and together with a " pair " of terminal cisternae ( bulbous enlarged areas of the sarcoplasmic reticulum ) it forms an arrangement called a triad.
3. It's difficult to find a and i bands in a sentence.