design: Purification of spermatogenic cells was performed as previously description{Zhang, 2017 #850}. Briefly, after collection and decapsulation, two testes were digested in EKRB buffer containing collagenase to disperse the testicular cells. The dispersed cells were washed, digested with trypsin and DNase I, and washed three times. Cells were suspended in  1PBS solution and processed to fixation steps. Our HiChew design process simplifies down to four key steps before PCR. First, we crosslink the DNA strands together by formaldehyde. Next, we treat the DNA on the GATC motif using DpnII. Then, we connect nearby digested DNA ends, leaving behind a GATC ligation scar this is based on the principle of proximal ligation. After cell breakdown, we can choose either a ligation-based or Tn5-based DNA library construction method, depending on the amount of DNA and your specific requirements.