Fig. 2From: Morphological and histological description of the midgut caeca in true crabs (Malacostraca: Decapoda: Brachyura): origin, development and potential roleMaja brachydactyla. Larval stages (zoea I, zoea II, and megalopa). Tissue organization of the midgut caeca. General diagram of the larval midgut caeca (A). Anterior midgut caeca (B–C): zoea II 6 days post-hatching, PAS-Alcian Blue contrasted with Haematoxylin, longitudinal cross section (B); and megalopa 6 days post-hatching, Mallory’s Trichrome, transversal cross section (C). Transition between the posterior midgut caecum and the midgut tract, Haematoxylin-Eosin, longitudinal cross section of the specimen (D–E): megalopa 6 days post–hatching (D), and newly hatched zoea I (E). Posterior midgut caecum, zoea II 6 post-hatching old, Mallory’s Trichrome, transversal cross section of the specimen (F). Anterior midgut caeca, megalopa 10 days post-hatching, TEM (G–H): general view (G), and detail of the myofibrils-like filaments (H). Posterior midgut caeca, megalopa 10 days post-hatching, TEM (I–J): general view (I), and detail of the myofibrils-like filaments (J). Scale bars (nm): 500 (H, J); (μm): 2 (I), 5 (G), 20 (B–F). Abbreviations: AC, anterior midgut caecum; arrow, midgut- hindgut junction; asterisk, midgut-stomach junction; BF, basal folds; BL, basal lamina; CE, midgut caeca epithelium; CT, connective tissue; HE, hindgut tract epithelium; ME, midgut tract epithelium; MF, muscle fibres; MGG, midgut gland; Mt, mitochondria; Mv, microvilli; My, myofibrils-like filaments; RER, rough endoplasmic reticulum; SE, stomach epithelium; PC, posterior midgut caecumBack to article page