FIG. 1.

Normal and preneoplastic lesions in zebrafish intestines. H&E. Bar=25 μm. (A) Normal zebrafish intestine, lined by a single layer of columnar epithelium. (B) Hyperplasia, with multilayered columnar epithelium and formation of mucosal inter-fold pseudocrypts involving the basal epithelium (arrows). Note pseudostratification of nuclei, but nuclei retain polarity. (C) Dysplasia, with nuclear atypia and cellular pleomorphism. Also, there is loss of normal histological architecture, loss of nuclear polarity, and aberrant mitotic figures (arrow). (D) Enteritis, chronic inflammatory cell infiltrate within the lamina propria (indicated by box). Note two presumptive aberrant pseudocrypt foci (arrows).