A) Schema of the single-cell-based droplet digital PCR (sc-ddPCR) system. Using the QX200 ddPCR system, each cell is simply encapsulated in one droplet. Up to 3,000 cells per well can be individually encapsulated. Subsequently, cell lysis and PCR with probes and primers are performed in each droplet. Finally, by quantifying the fluorescent droplets, single-cell genomic DNA is able to be assessed. B) Confirmation of single-cell encapsulation after generating droplets with a human B-cell line. Left, in bright field; right, with a Hoechst filter. C) Two-dimensional plot of signal amplitude of SRY and RPP30 probes in each droplet detected using our modified sc-ddPCR system. Signal amplitude of probes with 1× PBS as a blank control (left), a human female B-cell line (HEV0230) as a negative control (middle), and a human male B-cell line (HEV0057) as a positive control (right).