FIG. 4.

Immunohistochemical staining of duck liver sections with anti-PCNA monoclonal antibodies. Liver samples recovered on day 155 of the study were fixed, sectioned, and stained for the presence of PCNA. PCNA-positive nuclei are marked by arrowheads. Sections from control ducks (A to C), ducks in which cccDNA levels plateaued after an initial decline (D and E), and ducks in which cccDNA levels declined through the course of the study (F to H) are shown. The average frequency of PCNA-positive hepatocyte nuclei in three random fields of sections from each duck in each of the three groups (C, control; P, cccDNA plateaud; D, cccDNA declined) is also shown (I). Magnifications, ×160 (all panels)