Subject: When talking about muscle striations, is there a reason BANDS names?

The light areas are called the I-BANDS and the darker areas the A-BANDS. Near the center of each I-
BAND is a thin dark line called the Z-LINE .The Z-LINE is where adjacent sarcomeres come together and 
the thin myofilaments of adjacent sarcomeres overlap slightly. Thus, a sarcomere can be defined as the 
area between Z-lines..... Why are the called I bands and Z lines... Were these just random letters placed 
with the striation? Or is there a reason for this.?

Thanks

Re: When talking about muscle striations, is there a reason BANDS names?