Micrographs of hindgut immature of Chironomus sancticaroli. (A) cross-section between the transitional epithelium of the midgut and hindgut; (B) longitudinal section of the transition region between the mid and hindgut, showing the proctodeal valve (arrow); (C) in detail, epithelium of the proctodeal valve; (D) cross-section of ileum showing extensive muscle layer and the longitudinal folds formed by the epithelium (arrow); (E) longitudinal section of the colon and rectum; (F) cross-section of the epithelium of the colon and rectum demonstrating basal eosinophilia of the cell (arrowhead). p: epithelia; fd: food; lu: lumen; ml: muscle layer; mlp: Malpighian tubule, pm: perithrofic membrane; vep: valve epithelia. Stain: Harris hematoxylin and eosin. Scale bar=20μm.
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