Fig. 1. PCNA-like immunoreactivity throughout the locust midgut. (A) Panoramic view of locust midgut caeca walls. Strong immunoreactivity appears mainly in the core of the regenerative nests (arrows). (B) Ventricle wall. PCNA-like immunoreactivity is exclusively present in the cells of the regenerative nests at the base of the epithelium (arrows). Enterocytes surrounding the regenerative nests are progressively less stained, and no immunoreactivity is found in mature enterocytes outside the nests (arrowheads). (C) PCNA-like immunoreactivity in the locust ampullae of Malpighian tubules. PCNA-like immunoreactivity is found in clusters of regenerative cells (arrows). (D) PCNA-like immunoreactivity and BrdU-immunoreactivity in serial consecutive sections of the midgut in the caeca region. (E) Western blot analysis of locust gut tissue extract using antiserum against PCNA. A single band of 30 kDa is detected under reducing conditions. Lane 1, molecular mass markers; lane 2, locust gut extract; lane 3, negative control without antibody. Scale bars, 25 µm in A and 50 µm in B–D.