Ultrastructural and Molecular Changes in the Developing Small Intestine of the Toad Bufo regularis

Figure 2

Electron micrographs of the anterior portion of the small intestine of the prometamorphic stage 55 ((a)–(c)) and the metamorphic stage 60 ((d)–(h)) showing the following (a): apical cytoplasm with a well-developed microvilli (MV), numerous mitochondria (Mi), terminal web (TW) and tight junction (Tj). (b): the apical surface of the epithelium containing large goblet cell (GC) with mucus granules (MG). (c): epithelial-connective tissue interface showing the thin basal lamina (BL) under the larval epithelial (LE) cells. (d): a columnar epithelium with numerous lipid droplets (Ld). (e): intestinal epithelial cell with irregular nuclear envelop and chromatin condensation. (f): epithelial-connective tissue interface showing apoptotic bodies (arrows) in the larval epithelium. (g): apoptotic nucleus (AN) with chromatin condensation and irregular nuclear envelop. (h): discharging GC at the apical region. Scale bar = 1 μm.