FIGURE 2 in Morphological study of the digestive tract of the cardinal tetra, Paracheirodon axelrodi (Characiformes: Characidae)

FIGURE 2 | Histological sections of the digestive tract of Paracheirodon axelrodi, stained with Masson Trichrome. A. Longitudinal section of pharynx, showing a mucosa with a stratified squamous epithelium (SS) and underneath this, a layer of loose connective tissue and a thin inner circular layer and an outer longitudinal layer of striated muscle (StM). Pharyngeal teeth (arrows) and taste buds (arrowheads) were observed. B. Cross section of the esophageal mucosa with multiple foldings, composed by a pseudostratified epithelium (PE) and abundant mucous cells. A layer of loose connective tissue was observed, surrounded by a muscular tunica with an inner longitudinal and an external circular layer of StM. C. Detail of B showing pseudostratified epithelium (PE) with abundant mucous cells, a dense septum of connective tissue and external circular layer of StM. D. Transverse section of the first portion of the stomach. where a simple columnar epithelium (CE) formed by a layer of secreting mucus cells, short gastric glands (GG) and a circular layer of StM are observed. E. Transverse section of the fundic stomach which presents a simple columnar epithelium (CE) and long ramified gastric glands (GG) surrounded by a loose connective tissue. The muscular layer at this point contained two sublayers of smooth muscle (SM), a circular inner layer and an outer longitudinal layer. F. Detail of E showing GG composed by oxintopeptics cells (black arrow). G. Detail of E showing CE as a layer of secreting mucus cells. Asterisk, loose connective tissue; CE, simple columnar epithelium; GG, gastric glands; PE, pseudostratified epithelium; SM, smooth muscle; StM, striated muscle.