The in situ expression of the gene DPFP-BG20_A01 and EGP-BG97/192_B06 in zebra mussel foot tissue. The synthesized antisense RNA of DPFP-BG20_A01 was labeled with Alexa 488 dye (green) while the complementary RNA for EGP-BG97/192_B06 was labeled with Alexa 594 (red). The foot was cut along longitude as shown by the two paralleled dash lines across the foot. The positions of the byssus glands were labeled on the foot. The dash lines connected between slides and foot indicated the position of the three slides on the foot. a: The root area of zebra mussel foot including stem-forming gland; b: The middle region of the mussel foot containing thread-forming gland; c: The tip section of the foot including plaque-forming gland. T: Thread-forming gland cells.