Known antibodies against the beta chain of the HCG in the urine react with the
HCG. Red latex particles are attached to these antibodies. Known antibodies against
the alpha chain of the HCG are fixed to the membrane above and below the printed
blue "minus" sign. As the HCG molecules with bound antibody and red latex move
across the membrane with the urine, the alpha chain of the HCGs bind to the fixed
antibodies on the membrane creating the "plus" sign.
Microbiology Laboratory Manual by Gary E. Kaiser, PhD, Professor of Microbiology
is licensed under a Creative Commons Attribution 4.0 International License.
Last updated: September, 2017