Variation between microRNA libraries. Transcriptome profiles from samples at the same developmental state were compared within the three satellite cell libraries (2a), two individual adult biceps femoris libraries (2b), and two d 90 fetal biceps femoris libraries (2c). MicroRNA cDNA libraries for satellite cells (2a) were created from the pool of the 4th and 5th passage satellite cells and the 6th passage (6th passage, #1). A second library was created from a second flask of 6th passage stellite cells (6th passage, #2) to evaluate variation between satellite cells at the same passage. MicroRNA abundance is represented as number of individual miR tags observed per thousand tags evaluated.