The electrophoretic mobility of pyronin Y was measured in
tendon,
fi
brocartilage, and cartilage tissue specimens either par-
allel or perpendicular to the predominate collagen
fi
ber orienta-
tion. The measured electrophoretic mobility was greatest in the
compressive region of the tendon (
fi
brocartilage), followed by the
tensile region of tendon, and lowest in the cartilage